Despite efforts in foundation design, many larger buildings such as the Rahad Project and the. Asalaya Sugar ..... pier/pile and beam foundations or stiffened raft foundations. This is not true for ...... 2.1 - 2.7, NPTEL May 24, 2006. [37] Van der ...
Treatment of Expansive Subgrade Soils Using Lime and Fly Ash BY Omer Siddig Mustafa Hamza (B.Sc. Civil Eng., 2005, OIU)
A thesis submitted to the University of Khartoum in fulfillment of the requirements for the degree of M.Sc. in highway engineering
Department of Civil Engineering Faculty of Engineering Supervisor: Dr. Magdi Mohamed Eltayeb Zumrawi
August 2014
بسم اه الرمن الرحيم
ِ ِ ا ُ ُ يه ِ م ك اْ م ك ل ل ع ج ي ذ ل ل ع ج و ا د ه م ض َر ُ أ ُ الَ َ َ َ َ ُ أ َ َ أ ً َ َ َ َ َ أ َ ُ ُ ً ن ()01 لَ َعلَ ُك أم تَ أهتَ ُدو َ سورة الزخرف
I
DEDICATION
To the spirits of my parents, I plead God to bless and accept them To my family Samah Abdalla Doha & Millions of sons whom we belief in their future
II
ACKNOWLEDGEMENTS
I am very grateful to all the people who made this research possible, Dr. Magdi Zumrawi, Mr. Fathi Rahmtalla Eltyeb and all Soil laboratory teaching crew
Omer Siddig
III
Table of Contents اأيه Dedication Acknowledgement Table of Contents Abstract مستخ ص Abbreviations List of Figures List of Tables List of Plates
I II III IV V VI VII VIII IX X
Chapter One Introduction 1.1 Expansive Subgrade Soil 1.2 Soil Treatment 1.3 Problem Statement 1.4 Research Aims and Objectives 1.5 Research Methodology 1.6 Thesis Layout Chapter Two Literature Review 2.1 Introduction 2.2 Expansive Soil Characteristics 2.3 Pavements on Expansive Soils 2.4 Soil Treatment Methods 2.5 Soil Stabilization 2.6 Previous Investigations Chapter Three Experimental Work 3.1 Introduction 3.2 Materials used 3.3 Laboratory Testing 3.4 Data analysis 3.5 Discussion Chapter Four Conclusion 4.1 Summary 4.2 Recommendations References Appendix IV
1 2 4 6 7 7 8 8 11 13 18 25 31 31 34 44 53 57 58 60 63
Abstract: This research investigates the improvements in the properties of expansive soils, as road subgrade stabilized with lime and fly ash in varying percentages. Laboratory tests were undertaken to study the swelling and strength characteristics of expansive soils stabilized with lime, fly ash and a combination of both. Lime and fly ash were added separately to expansive soil at ranges 0-15% and 0-40%, respectively. Index property, Compaction, California Bearing Ratio (CBR), Unconfined Compression Strength (UCS), free swell and swelling pressure tests were performed on natural and treated soil samples. The soils were obtained from different sources. The soil samples used in this study were highly expansive and very highly expansive, depending on the primary tests. The lime engaged was hydrated lime obtained from local kilns in Kassala. The fly ash was class F, obtained from Gary Electrical Station in Khartoum North. For the investigated admixture lime-fly ash; the amounts of lime added (5% and 8%) were combined with the fly ash contents 0%, 5% and 10%. Comparing the results obtained from the tests carried out on the natural and treated samples, the CBR and UCS of lime-fly ash treated samples increased significantly, coupled with the swelling reduction, depending on additive content and type of soil. It could be concluded that stabilization of expansive subgrade soils by lime-fly ash admixture is successful and more economical.
V
مستخلص: هذا البحث يدرس تحسين خ اص التر المتمدده كأس س ل طري عند تثبيت ب لجير الرم د بنس مخت .أجري إختب را معم ي لدراس خص ئص اإنت ح الم م ل تر المتمدده بعد تثبيت ب لجير ,الرم د اإثنين مع .تم إض ف الجير الرم د كل ع ي حدا ل ترب المتمددة في المدي % 0 – 0 %5 – 0ع ي الت الي .إختب را حد د أتربيرج ,الدم ,نسب التحمل الك لي رنيه ,م م الضغط الغير محص ر ,نسب اإنت الحر ضغط اإنت أجري ع ي عين الترب الطبيعي ع ي عين الترب المع لج . أخذ عين الترب من من ط مخت .عين الترب التي أستخدم في هذه الدراس ك ن ترب ذا تمدد ع لي ترب ذا تمدد ع لي جدا ع ي أس س اإختب را اأ لي التي أجري .الجير المستخد ك ن جير م درج مأخ ذ من أفران مح ي من كسا .أم الرم د فك ن رم د صنف (ف) مأخ ذ من محط قري الحراري في الخرط بحري .تم إض ف الجير الرم د )%جير مزج مع الترب محت ي ع ي نس رم د % ,%0 مع في الترب بتركيب ت في إض ف نس ( % .%50 ع ي عين الترب المع لجه ,ذاد نسب التحمل بم رن نت ئج اإختب را التي أجري ع ي عين الترب الطبيعي الك لي رنيه ذاد م م الضغط الغير محص ر ل عين المع لجه ب لجير الرم د ,مع ت ص اإنت حس كمي الم اد المض ف ن ع الترب .في الخاص يمكن ال ل بأن تثبي التر المتمددة بإض ف الجير – الرم د ن جح إقتص دي.
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Abbreviations Abbreviation AASHTO
ASTM B BDE BRRI BS Cc CBR ESAL GBFS HMA IBV LL M.C MDD MR NP OMC RHA PCC PI PL TRL UCS
Description American Association of High ways and Transportation Organization American Society of Testing and Materials Water – plasticity ratio Bureau of Design and Environment Building and Road Research Institute British Standard Compression Index California Bearing Ratio Equivalent Single Axle Load Granulated Blast Furnace Slag Hot-Mix Asphalt Immediate Bearing Value Liquid Limit Moisture Content Maximum Dry Density Resilient Modulus
Non-plastic Optimum Moisture Content Rice Husk Ash Portland cement concrete Plasticity Index Plastic Limit Transport Research Laboratory Unconfined Compression Strength
VII
List of Figures Figure
Page
Fig 1.1: Expansive soils in Sudan, Wayne et al (1984)
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Fig 2.1: Commonly used criteria for determining swell potential, Yilmaz (2006) Fig 2.2: Water content profiles in the active zone, Nelson and Miller (1992) Fig 2.3: Sudan Soil Map, Elsharif (2001) Fig 3.1: Sudan and South Sudan map showing the locations of the soils used in this study Fig 3.2: Free swell versus additives percent relationship for Medani soil Fig 3.3: Free swell versus additives percent relationship for Gedarif soil Fig 3.4: Free swell versus Lime percent relationship for Medani soil Fig 3.5: Free swell versus Lime percent relationship for Gedarif soil Fig 3.6: Plasticity index versus additives percent relationship for Medani soil Fig 3.7: Plasticity index versus additives percent relationship for Gedarif soil Fig 3.8: Plasticity index versus lime percent relationship for Medani soil Fig 3.9: Plasticity index versus lime percent relationship for Gedarif soil Fig 3.10: Dry density versus moisture content relationship for Medani soil Fig 3.11: Dry density versus moisture content relationship for Gedarif soil Fig 3.12: Free swell versus additives percent relationship for Medani and Gedarif soils Fig 3.13: Swelling pressure versus additives percent relationship for Medani and Gedarif soils Fig 3.14: California bearing ratio versus additives percent relationship for Medani and Gedarif soils compacted at the optimum moisture content. Fig 3.15: Unconfined compression strength versus additives percent relationship for Medani and Gedarif soils compacted at optimum moisture content
9 11 22
VIII
32 48 49 49 50 50 51 51 52 52 53 54 54 55 56
List of Tables Table
Page
Table 2.1: Expansive soil classification based on the soil plasticity, Holtz and Gibbs (1956) Table 2.2: Potential Expansiveness, for each of which an estimate of heave is given in mm per meter of profile, Merwe (1964) Table 2.3: Soil Treatment methods applied to expansive soils, Nelson and Miller (1992) Table 2.4: Cement requirement by volume for an effective stabilization of various soils, Das (2011) Table 2.5: Lime deposits in Sudan, Elsharif (2001) Table 2.6: Results of Lime Stabilized Expansive Clay, Elsharif (2001) Table 2.7: The chemical properties of fly ash as reported by Abadi, (2014) Table 3.1: The tests results for the studied samples pre-treatment Table 3.2: Atterberg's limits and swell percent tests results for Medani soil stabilized by and fly ash Table 3.3: Atterberg's limits and swell percent tests results for Gedarif soil stabilized by lime and fly ash Table 3.4: The tests results for Medani soil stabilized by optimum lime and fly ash content Table 3.5: The tests results for Gedarif soil stabilized by optimum lime and fly ash content Table 3.6: The stabilizers effect on free swell for the studied soils Table 3.7: The stabilizers effect on plasticity index for the studied soils
IX
8 9 17 19 23 23 25 44 45 46 47 47 53 55
List of Plates Plate
Page
Plate 1.1 Natural expansive clay in a valley south of Alfula in South Kordufan
2
Plate 1.2 Cracks on top of earth road at Baleela in South Kordufan Plate 2.1: Expansive virgin soil in South Kordufan Plate 2.2: Fly Ash used in this search Plate 3.1: The appearance of the clay soil at Soba in Khartoum Plate 3.2: The soil sample taken from Madani in Gezira Plate 3.3: The soil sample obtained from Gedarif Plate 3.4: The set of sieves used in testing Plate 3.5: Casagrande device and tools used for liquid limit measurement Plate 3.6: The apparatus and tools used for sample preparation in laboratory Plate 3.7: The compaction test apparatus and tools used in the study Plate 3.8: The CBR test machine used in the study Plate 3.9: The jack used in releasing the sample after CBR test Plate 3.10: The cylinders used the free swell test Plate 3.11: A sample mounted on consolidation apparatus during the swelling test Plate 3.12: The portable unconfined compression strength test machine used in the study
6 13 24 33 33 33 34 36 37 38 39 40 41
X
42 43
Chapter One Introduction 1.1 Expansive Subgrade Soil The performance of pavements depends upon the quality of subgrades. A stable subgrade definitely helps to produce a long- lasting pavement due to support provided to the pavement system, therefore the quality of the subgrade will greatly influence the pavement design and the service life of the pavement. Roads running in expansive areas are known for bad condition and unpredictable behavior for the soil contributes to some extent. The failure of roads, in form of heave, depression, cracking and unevenness are caused by the seasonal moisture variation in the expansive subgrades, however, expansive subgrade will not cause a problem if its moisture remains constant. Expansive clay is a clay that prone to large volume changes that are directly related to changes in water content, on other words this type of soil heave in vicinity of water in fall season, heave occurs as a result when water fill voids of soil and commonly soil will often enlarge and making a great upward force can be strong enough to damage structures erected on this soil. In dry seasons this soil lose water dropped inside and leave air voids so this lead to great shrink even if there is no loads applied. But when expansive soils are present they will generally not cause a problem if their water content remains constant. The situation where greatest damage occurs is when there are significant or repeated moisture content changes. The mineral make-up of this type of soil is responsible for the moisture retaining capabilities. Soils with smectite clay minerals, including montmorillonite, have the most dramatic swelling properties. Expansive soils typically contain one or more of these clay minerals: montmorillonite, smectite, bentonite and illite. Expansive soil is high plasticity clay that cover a wide regions around earth, it has different names as shrink-swell soil, black cotton soil, black earth, cracking soil, problem soil, London clay and hidden hazard. Ge e all it’s ofte la k soil de o st ate a g eat defo atio affe ts ith diffe e es of moisture contents supplied, this soil imbibe water along fall season in the vicinity of water hence this, enlarge soil mass accordingly, as well as minimize shear strength, tend to be compressible as a consequence of undesirable engineering properties, on other side when d ied it’s sh i k as a esult of losi g ate hi h left g eat oids. While this soil wetting, volume expand accordingly and so producing a very high uplift force. 1
This soil has a considerable clay content of more than 30% (soil fraction less than 2µm) and it has high liquid limits and low plastic limits therefore high plasticity index. Many of Sudan countryside covered by black cotton soil even some urban areas, a long Nile basin, south of Khartoum, all valleys, even in urban regions as Khartoum, Gezeera, but its presence significantly in Gedarif state, and area covered by expansive soil is estimated by 1 million Km2 of total area of both Sudan and South of Sudan.
Plate 1.1: Natural expansive clay in a valley south of Alfula in South Kordufan 1.2 Soil Treatment Treatment of unsuitable subgrade soils is generally accomplished by modification, stabilization, or removal and replacement. Modification refers to a short-term subgrade treatment that is intended to provide a stable working platform during construction. Stabilization refers to a subgrade treatment intended to provide structural stability for improved long-term performance and this is the main topic of this search. Removal and replacement, as the name indicates, involves removal of the unsuitable subgrade soil and replacement with a select material (usually granular backfill). The choice of a specific treatment depends on many factors, including: soil type; required treatment depth; construction variables (cost, availability, and time); treatment objective 2
(short-term vs. long-term); and project location (urban vs. rural). The most commonly treatment is expansive soil stabilization. The use of additives is generally the most economical treatment method for rural projects. In urban areas, removal and replacement is often preferred because the use of additives creates dust and environmental concerns. The remainder of this advisory focuses on these two methods. Additives are of two types: reactive, such as lime; and self-cementing, such as Portland cement, slag modified Portland cement, and fly ash. Reactive additives chemically react with the clay fraction in the soil to produce desirable changes in the engineering properties of the soil. Plasticity, workability, shrink-swell potential, and strength of fine-grained soils can generally be improved with the addition of lime. The degree of improvement depends on such factors as soil type, type and percentage of lime, length of cure, soil temperature and soil moisture conditions at the time of curing. In general, lime does not require a curing period for the treated subgrade to achieve the required stability when used for modification. When used for stabilization, lime requires seven days of curing. For lime modification, the optimum lime content is the percent lime that provides a minimum immediate bearing value (IBV) of 10 percent, Dirksen (2005). For lime stabilization, the optimum lime content is the percent lime that results in a stabilized soil strength gain of 50 psi (345 kPa) over the untreated soil, and provides a minimum compressive strength of 100 psi (690 kPa) for sub-bases, and 150 psi (1035 kPa) for bases Dirksen (2005). The success of lime modification or stabilization depends on the soil-lime reactivity, which largely depends on the clay fraction in the soil. On the average, 15 to 20 percent clay fraction is necessary to ensure reactivity and provide the required IBV, Dirksen (2005). In granular soils such as silts, sands, and gravels, the clay fraction is too small and the soil-lime reactivity is too negligible to result in any improvements in the soil properties. In this case, soil treatment with self-cementing additives, such as Portland cement or fly ash, becomes an alternative. Self-cementing additives do not necessarily react with the soil or aggregate, but rather bind the natural materials together, increase strength, and provide some degree of waterproofing. For modification with self-cementing additives, the performance criterion requiring a minimum IBV of 10 remains the same. For stabilization with Portland cement or slag modified cement, the optimum cement content is that which results in a minimum compressive strength of 500 psi (3450 kPa), without practically affecting the compaction and durability (freeze/thaw and wetting/drying) characteristics of the soil-cement mixture, Dirksen (2005). Dirksen (2005) noticed that fly ash can increase both the IBV and compressive strength of certain soils. Fly ash was found to require two to three times the application rate of lime for clayey soils, and may not be economical in such applications. However, fly ash was also found 3
to be effective at strengthening silty and sandy soils that may not adequately react with lime. In these cases, modification with fly ash may provide a lower cost alternative to removal and replacement. 1.3 Problem Statement As stated above expansive soil have a great deformation directly related to water content, this deformation caused by volume changes make costly problems with roads and other structures, expansive clay expand greatly in the vicinity of water hence this expand produce a very high uplift force can be strong enough to occur bending, damages and soil will be compressible so unfair settlements will occurs mostly, therefore any damages occurs with the road sub base or base layers will be reflected to the pavement layers accordingly. Expansive soil as roads subgrade often result in costly remedial maintenance around the worldwide as the cost of annual damages to manmade structures resulting from expansive soil in USA cost billions of dollars. According to US Department of Housing and Urban Development, the repair of damage on infrastructures caused by expansive soils costs about 9 billion dollars per year. In Sudan one million km2 of land is approximated covered by expansive soils. After a yearlong investigation of different regions in Sudan according to Wayne et al (1984), an estimated USD 6,000,000 in damages was calculated to be caused by heaving and shrinking soils. One of many examples, the Rahad Project is an irrigated farm project where the staff housing buildings have succumbed to expansive soils and were found to have large cracks in interior walls. Many factories and production plants around the region were found to have similar cracking to their structures. The Asalaya and Sennar Sugar Factory, Friendship Cotton Mill, and Gezira Tannery are all examples of properties where structures were found to have cracking or failed completely, (Wayne 1984). As shown in Fig 1.2 below, damages found in structures due to expansive soils are located in close proximity to the Nile River. In Khartoum, the capital and largest city of Sudan, damages to roads, buildings, and utility piping are common and amount to millions of U.S. dollars per year for repair costs.
4
Fig 1.1: Expansive soils in Sudan, Wayne et al (1984) Despite efforts in foundation design, many larger buildings such as the Rahad Project and the Asalaya Sugar Factory have succumbed to expansive soil damages. A specific type of soil known as Black Cotton Soil exists throughout the entire Rahad property and the heaving from water absorption caused many concrete piles to fail where the reinforcement was terminated. In the case of the Asalaya Factory, the potential for water seepage into the slab was accounted for by encasing the top 3m (9.8 ft) of the supporting piles in plastic pipe and providing polyethylene 5
sheeting beneath the slab. Despite these efforts, damages from the soil have been estimated to exceed the original construction costs by a factor of three (Wayne 1984).
Plate 1.2: Cracks on top of earth road at Baleela in South Kordufan 1.4 Research Aims and Objectives Construction of roads often requires using granular soil materials in a very large. In urban areas borrow earth is not easily available which have to be hauled from far distances, quite often large areas are covered by high plasticity expansive clay which is not suitable for such purpose. Extensive researchers have been carrying this out to enhance performance of expansive clay, and good results have been reported. It seems very important to improve the subgrade soils of expansive clays in order to reduce swelling brought to both roads and buildings and to ignore high cost resulted by either continuously remedial maintenance or hauling granular soil from far distances. The most economical methods to be adopted are the soil stabilization by using local materials. 6
This research study the possibility of using available local materials as stabilizer to reduce or minimize swelling and enhance expansive soil properties to be used as roads subgrade. Lime and fly ash have been used as soil stabilizer in this study. Lime has demonstrated a great interaction to enhance expansive soil in either this search or previous searches, however, fly ash used in this search to reduce cost of treatment by reducing lime amount due high cost of lime. 1.5 Research Methodology This research essentially based on laboratory testing, to access an acceptable amount of additives which can improve expansive soil in order to be used as roads subgrade. Expansive soil covers large areas in Sudan, a d it’s ostl to t a spo t suitable materials from far distances to be used as road’s subgrade. It is of benefit to treat the existing subgrade. The methodology of this research is the experimental work attempts to treat expansive soils by lime only, fly ash only and lime with fly ash together, to variant soil samples taken from different areas in Sudan. This practice of soil treatment was done through experimental work performed by conducting laboratory tests. 1.6 Thesis Layout Thesis has been sectored into main four chapters. Chapter one introducing to the study, it consists of sections that describing expansive soil in general, problems brought to roads due to expansive soil, treatment of expansive soil, research aims and methodology. Chapter two is the literature review. That consist the theory of expansive soil characteristics, pavements on expansive soils, treatment methods beside the previous investigations in soil treatment techniques. Chapter three is the experimental work of this study that describes the soil samples collected, the experimental tests, results, analysis and discussion. Chapter four is assigned for conclusion and recommendations.
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Chapter two Literature Review 2.1 Introduction This chapter reviews the expansive soil in general, problems transferred to roadways and buildings as well, and possibility of treatment methods. Section one introduces to the chapter. Section two reviews the characteristics of expansive soil and its engineering properties. Section three describes pavement on expansive soil and the factors controlling performance of pavement on such soil, treatment methods defined in section four including treatment methods tracked in Sudan, soil stabilization in general as well as some chemical stabilization. The last section reviews previous investigations in such theme in Sudan and worldwide as well. 2.2 Expansive Soil Characteristics Many efforts have been made to find a universally applicable system for the classification of shrinking and swelling in order to characterize the expansive soil. Some have even attempted to produce a unified swelling potential index using commonly used indices, e.g. Sridharan and Prakash (2000), Kariuki et al (2004) and Yilmaz (2006) or from specific surface areas, YukselenAksoy and Kaya (2010), but these are as yet to be adopted. Examples of various schemes commonly used around the world are illustrated in Figure (2.1). Core to the various schemes that have been developed is the lack of standard definitions of swell potential, since both sample conditions and testing factors vary over a wide range of values, Nelson and Miller (1992). But main properties that which expansive soils to be identified accordingly are limits, swelling potential and strength as illustrated in tables (2.1), (2.2) and (2.3). Table 2.1: Expansive soil classification based on the soil plasticity, Holtz and Gibbs (1956) Shrinkage Limit >15 10 - 15 7–2 70
Plastic Limit 35
8
Potential for Volume Change Low Medium High Very High
Table 2.2: Potential Expansiveness, for each of which an estimate of heave is given in mm per meter of profile, Merwe (1964) Classification Low expansiveness Medium expansiveness High expansive Very high expansive
Heave per meter of profile 0 mm 20 mm 40 mm 80 mm
Fig 2.1: Commonly used criteria for determining swell potential, Yilmaz (2006) 9
Expansive soils present significant geotechnical and structural engineering challenges the world over, with costs associated with expansive behavior estimated to run into several billions annually. Expansive soils are soils that experience significant volume change associated with changes in water contents. These volume changes can either in the form of swell or in the form of shrinkage and this is why they are sometime known as swell/shrink soils. Key aspects that need identification when dealing with expansive soils include: soil properties, suction/water conditions, water content variations temporal and spatial, e.g. generated by trees, and the geometry/stiffness of foundations and associated structures. Expansive soils can be found in humid environments where expansive problems occur with soils of high Plasticity Index (PI) or in arid/semi-arid soils where soils of even moderate expansiveness can cause significant damages around the world, e.g. in part of Africa, Australia, India, United States, United Kingdom and Canada. In these countries one of the problems having great impact on the construction and maintenance costs of highways is expansive soils effects. Whenever insufficient attention is given to the deleterious properties of expansive soils, the results will be premature pavement failure evidenced by undulations, cracks, potholes and heave. As far as Sudan is concerned expansive soils cover large areas in Central, Eastern and Southern states. As these a eas i lude ost of the atio ’s populatio enters and development schemes an adequate and sustainable road communication system is always needed. Expansive clay can be characterized by its potential for volume changes as well as can be characterized by its high strength when dry, very low strength when wet, wide and deep sh i kage a ks i the d seaso , high plasti it a d e poo t affi a ilit sti ki ess he wetted. These characteristics affect the performance of light structures such as pavements built on these soils. Methods were developed for the identification and classification of expansive soils both locally and worldwide. In Sudan all grayish and/ or brownish clays with plasticity index greater than 25% can be identified as expansive. The classification or rating (from low potential to high heave potential) usually depends on the clay content and plasticity, Merwe (1964)
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Fig 2.2: Water content profiles in the active zone, Nelson and Miller (1992) 2.3 Pavements on Expansive Soils Constructing roads on expansive subgrades should be consumed with special design criteria and should be paid more attention due to weak engineering properties of expansive soil and shrink/ swell behavior. Zumrawi, (2013) placed design parameters as follows: • Traffic load application is given in terms of Equivalent Single Axle Load (ESAL). • Subgrade strength is measured in terms of the California Bearing Ratio (CBR) or the Resilient Modulus (MR) of the soil. Compaction of subgrade soil will increase its density and strength and prevent excessive settlements under traffic loading. Expansive clays are liable to show serious decrease in strength when compacted at high moisture contents. They should be compacted at low to optimum moisture content zone to increase strength. • Swelling Potential is defined in ter s of t o ai o po e ts s ell pe e t a d s elli g p essu e . Holtez, (1959) defined swell percent as the percentage of total volume change of a soil when tested in an oedometer cell such that its moisture content varies from the air-dry to the saturated o ditio u de a e ti al su ha ge p essu e of 5 psi ≈ Kpa . The s ell pe e t is usually measured under a small vertical surcharge pressure (7 to 20 Kpa). The swelling 11
pressure is equivalent to the pressure, which must be applied to prevent swelling (or volume change) of the soil sample when water is fed into it. In design it is quite important to measure swell percent and swelling pressure of the subgrade expansive soil. • Construction material properties: most of the empirically based design methods such as ASHTOO, Transport Research Laboratory (TRL) and CBR methods account for variations in materials properties and allow the overall thickness to be reduced. This will increase the strength of the materials above the minimum values required by the specification. Furthermore Zumrawi, (2013) described design guidelines as the previous studies recommendations and experience of design adopted by similar countries to Sudan, the guidelines for flexible pavement design of roads on expansive soils described as: • Removal of subgrade: Zumrawi, (2013) had e o e ded to e o e the su g ade if it’s CBR less than 3% or its resilient modulus (MR) less than 20 MN/m2. • Surface and Subsurface drainage: in this way he recommends to prepare a proper surface slopes in both longitudinal and transverse direction and use a filter layer below the subbase. • Bituminous surfacing. • Base and subbase course should be designed as per pavement design methods based on CBR and traffic loading. • The most economical way is to improve the subgrade using the available local materials to enhance soil properties. Based on Elsharif (2001) 38% of roads network in Sudan has been constructed on expansive soil. The major highways such as Khartoum- Wad Madani- Kassala, Wad Madani- Sennar- Kosti, Sennar- Singa- Damazin and Khartoum- Kosti are wholly laid over highly expansive subgrades. The subgrade characteristics that affect the performance of pavements laid over expansive subgrades suggested by Elsharif (2001) are: • The very low wetted strength. Expansive soil demonstrates very low CBR values when fully saturated, values as low as 2% are common. These soils are therefore characterized as poor subgrade and will need some kind of treatment. • The potential for heave especially when lightly loaded as is the case for pavement loading. The traffic load here is transitional and moving, therefore, is not effective in suppressing heave whenever the subgrade is wetted. • Shrinkage of wetted subgrades. The subgrade soil on the pavement shoulders is subjected to environmental changes resulting in sequences of wetting and drying. Drying causes shrinkage of the subgrade soil and is reflected on the pavement surface as longitudinal cracks. The shrinkage cracks in the soil on the sides of the pavement. These cracks are deep (greater than 0.1m) in arid areas and could allow seepage of water to the subgrade. 12
Expansive soils are encountered in low terrain and relatively high embankment often needed to raise the level of the road. In many cases these embankments are built from the surrounding expansive soils. For the structural layers there is always scarcity in good natural construction materials that can be used as subbase and base courses. Designing economical and good performing pavements on expansive soils is always a challenge. This challenge is greater in arid areas.
Plate 2.1: Expansive virgin soil in South Kordufan 2.4 Soil Treatment Methods Essentially, treatment of expansive soils can be grouped under two categories: • Soil Stabilization: removal/replacement, remould and compact, pre-wetting and chemical/cement stabilization. • Water content control methods: horizontal barriers (membranes, asphalt and rigid barriers), Vertical barriers, electrochemical soil treatment and heat treatment. A detailed account of the various treatment approaches is provided by Chen (1988) and, Nelson and Miller (1992) with a detailed review of stabilization over the last 60 years provided by Petry and Little (2002). As with any treatment approach it is essential to undertake appropriate site 13
investigations and evaluations and a brief discussion pertinent to expansive soils has been discussed above. Special consideration should be given to depth of active zone, potential for volume change, soil chemistry, water variations within the soil, permeability, uniformity of the soils and project requirements. A brief overview of each of the two categories of treatments applied to expansive soils is provided below, with Table 2.3 providing brief details of soil stabilization approaches. In a recent survey Houston et al (2011) found that many geotechnical and structural engineers considered chemical stabilization approaches such as the use of lime as ineffective for pretreatment of expansive soils for foundations. Preference is typically given for use of either pier/pile and beam foundations or stiffened raft foundations. This is not true for pavements, where lime and other chemical stabilization approaches are commonly used across the world. The various stabilizers can be grouped into three categories Petry and Little (2002): • T aditio al stabilizers: lime and cement. • B -product stabilizers: cement/lime kiln dust and fly ash. • No -traditional stabilizers: sulfonated oils, potassium compounds, ammonium compounds and polymers. Further details of these can be found in Petry and Little (2002). However, as with any soil treated with lime care is needed to assess chemical as well as physical soil properties to prevent swelling from adverse chemical reactions, Petry and Little (2002). For example Madhyannapu et al (2010) provide details of quality control when stabilizing expansive subsoils using deep soil mixing, demonstrating the use of non-destructive tests based on seismic methods. Chemical stabilization can be used to provide a cushion immediately below foundation placed on expansive soils, e.g. pavements, Murty and Praveen (2008). Several methods for dealing with expansive soil problems when designing pavements on expansive soils were studied, discussed and some applied include: • Realignment: This option is possible only if the areas covered with expansive soils are of limited extent, therefore, the route of the roadway can be changed. Therefore the option is not always available nevertheless an economical alignment is always needed. • Excavation and Replacement: This approach is economically practicable if the expansive soil layer is thin and suitable backfill material is available in the vicinity of the road. • Prewetting or Ponding: This approach has been successfully practiced in the United States and South Africa, Krazynski (1980). The amount of water needed for ponding is such that the moisture content would be raised to about 2 to 4% above the plastic limit, African Highway 14
Conference (1980). This option is questionable in arid climates due to expected shrinkage problems and also where the expansive soil is deep. • Use of improved subgrade layer: The improved subgrade is usually a non-expansive soil of acceptable strength and low permeability. This has an advantage of reducing the subbase thickness and protecting the subgrade from moisture changes. The Kenyan Road Design Manual, Kenyan Road Design Manual (1980) recommended a minimum thickness of 30cm for the improved subgrade or capping layer. • Surcharging Expansive Soils: It is well known that placing a substantial thickness of nonswelling material over expansive clays reduces heave. The Kenyan Road Design Manual recommends that the total thickness of pavement plus the improved subgrade to be at least 60cm. This approach is not effective over soils of high swelling potential. • Using Sand Trenches: The function of a vertical sand trench is to act as a water balance reservoir. The predominant pavement distress was found to depend on the moisture conditions of the subsoil. For dry subsoil shrinkage cracks provide good passage for free water resulting in differential volume change in the soil beneath the pavement. In such case water proofing membrane must be installed along the trench and then backfilling is required with bituminous sealing along the trench surface. • Preventing Moisture Changes in Pavement Layers: This is attainable by: a) The pavement layer should be as impermeable as possible by using proper bituminous seal cover; b) Shoulders should be impervious with proper width (about the active zone) and if necessarily sealed or even surface dressed and sloped 1:4 outwards; c) drainage culverts should not be of pre-cast units so as to avoid the problems from joints; d) side ditches should be as far away as practicable from the pavement; and e) bedding and surrounding soils of culvert shall be of well compacted non-swelling material of good resistance against scour. • Mechanical Stabilization: This is achieved by mixing a non-expansive soil with the expansive clay. The non-expansive soil is usually sand or sandy and/ or gravelly material. Generally mechanical stabilization of heavy clays is not practical, as large percentage of nonexpansive material will be needed to be added. • Cement Stabilization: Cement stabilization is widely used in road construction. The process involves pulverization of natural material, spreading of cement and mixing with the clay soil, watering and immediate compaction. Cement stabilization is best suited to granular materials. Cement was also found to reduce plasticity, swelling potential of clay soils and markedly improve soil strength. A study was conducted in the Building and Road Research Institute at university of Khartoum by Osman and Mustafa (1983) on two clay soils from central Sudan. It was found that the addition of up to 10% of ordinary Portland cement by weight to these soils is markedly reduced their plasticity index (from almost 40% to less than 10%). In India, Uppal
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(1959) addition of up to 15% of cement was needed to markedly improve the engineering properties of India black cotton soils. • Lime Stabilization: The stabilization of clays by hydrated lime has been demonstrated by many researchers and has shown out good results. The technique has been widely used in road engineering. Lime stabilization had very limited use in Sudan although the studies and research on lime stabilization of expansive clay soils showed very promising findings, Mohamed and Walker (1963). Elsharif (2001) suggested some technical treatment techniques for expansive soils as follows: • The CBR of the embankments should be greater than 5% and imported fill should be used when the subgrade materials are of CBR< 5%. Usually this treatment needs a thin protective layer of impervious non-expansive materials to be laid on the side slopes but it was not recommended. • A capping layer or improved subgrade is always required on the top of the embankment when the CBR of the embankment material is less than 8%. The capping materials are gravely sand, mechanically stabilized clay with gravel or sand, or lime stabilized clay. It is noteworthy to mention that gravely sand or mechanical stabilized clay may be a problematic previous layer. • Some designer required the use of a layer of selected materials of CBR >15% on the top of the embankment mainly to reduce the thickness of the subbase and to act as a capillary cut off between the embankment and the upper permeable subbase materials. • Sand trenches were proposed for Sennar – Singa – Damazin Road but not implemented as they are laborious and time consuming. It is clear from the recommendations of the researcher that there is a general agreement that the encountered soils are very poor subgrades and there is a desperate need to improve their strength and also reduce their potential for heave. However, most of these treatments concentrate on the improvement side. In many cases the CBR of the subgrade is less than 4% and no better material is available nearby. The embankments therefore are built from nearby borrows. The only advantageous treatment which can improve strength, reduce plasticity and swelling potential is the addition of lime. This option has been recommended by some of investigators.
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Table 2.3: Soil Treatment methods applied to expansive soils, Nelson and Miller (1992) Improvement Outline of approach
Advantage
Disadvantage
Expansive soil removed and replaced by non-expansive fill to a depth necessary to prevent excessive heave. Depth governed by weight needed to prevent uplift and mitigate differential movement. Chen (1988) suggests a minimum of 1 to 1.3m.
Non-expansive fill can achieve increase bearing capacities; Simple and easy to undertake; Often quicker than alternatives.
Preferable to use impervious fill to prevent water ingress which can be expensive; Thickness required may be impractical; Failure can occur during construction due to water ingress.
Less expansion observed for soil compacted at low densities above OWCa than those at high densities and below OWCa (see Figure 15). Standard compaction methods and control can be used to achieve target densities.
Uses clay on site eliminating cost of imported fill; Can achieve a relatively impermeable fill minimizing water ingress; Swell potential reduce without introducing excess water.
Low density compaction may be detrimental to bearing capacity; May not be effective for soil of high swell potential; Requires close and careful quality control.
Has been used successfully when soils have sufficiently high permeabilities to allow relatively quick water ingress, e.g. with fissure clays.
May require several years to achieve adequate wetting; Loss of strength and failure can occur; Ingress limited to depth less than the active zone; Water redistribution can occurs causing heave after construction.
All fine grained soils can be treated by chemical stabilizers; Is effective is reducing plasticity and swell potential of an expansive soil.
Soil chemistry may be detrimental to chemical treatment; Health and safety needs careful consideration as chemical stabilizers carry potential risks; Environmental risk may also occur – e.g. quick lime is particularly reactive; Curing inhibited in colder temperatures.
approach
Removal & replacement
Remolding & compaction
Pre-wetting or ponding
Chemical Stabilization
a
Water content increased to promote heave prior to construction. Dykes or berms used to impound water in flooded area. Alternatively trenches may be used and vertical drains can be used to also speed infiltration of water into soil. Lime (3 to 8% by weight) common with cements (2 to 6% by weight) sometimes used, and salts, fly ash and organic compounds less commonly used. Generally lime mixed into surface (~300mm), sealed, cured and then compacted. Lime may also be injected in slurry form. Lime generally best when dealing with highly plastic clays.
OWC – optimum water content as determined by standard proctor test, BS1377 (1990).
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2.5 Soil Stabilization Soil stabilization involves the use of stabilizing agents (binder materials) in weak soils to improve its geotechnical properties such as compressibility, strength, permeability and durability. The components of stabilization technology include soils and or soil minerals and stabilizing agent or binders (cementitious materials). Most of stabilizations have to be undertaken in soft soils (silty, clayey peat or organic soils) in order to achieve desirable engineering properties. According to Sherwood (1993) fine-grained granular materials are the easiest to stabilize due to their large surface area in relation to their particle diameter. A clay soil compared to others has a large surface area due to flat and elongated particle shapes. On the other hand, silty materials can be sensitive to small change in moisture and, therefore, may prove difficult during stabilization, Sherwood (1993). Peat soils and organic soils are rich in water content of up to about 2000%, high porosity and high organic content. The consistency of peat soil can vary from muddy to fibrous, and in most cases, the deposit is shallow, but in worst cases, it can extend to several meters below the surface, Pousette et al (1999), Cortellazzo and Cola (1999) and Åhnberg and Holm (1999). Organic soils have high exchange capacity; it can hinder the hydration process by retaining the calcium ions liberated during the hydration of calcium silicate and calcium aluminate in the cement to satisfy the exchange capacity. In such soils, successful stabilization has to depend on the proper selection of binder and amount of binder added, Hebib and Farrell (1999), Lahtinen and Jyrävä (1999) and Åhnberg et al (2003). These are hydraulic (primary binders) or non-hydraulic (secondary binders) materials that when in contact with water or in the presence of pozzolanic minerals reacts with water to form cementitious composite materials. The commonly used binders are Cement, Lime, Fly ash and Blast furnace slag. 2.5.1 Cement Stabilization Ce e t is the oldest i di g age t si e the i e tio of soil sta ilizatio te h olog i 5 0’s. It may be considered as primary stabilizing agent or hydraulic binder because it can be used alone to bring about the stabilizing action required, Sherwood (1993) and Euro Soil Stab (2002). Cement reaction is not dependent on soil minerals, and the key role is its reaction with water that may be available in any soil, Euro Soil Stab (2002). This can be the reason why cement is used to stabilize a wide range of soils. Numerous types of cement are available in the market; these are ordinary Portland cement, blast furnace cement, sulfate resistant cement and high alumina cement. Usually the choice of cement depends on type of soil to be treated and desired final strength. 18
Hydration process is a process under which cement reaction takes place. The process starts when cement is mixed with water and other components for a desired application resulting into hardening phenomena. The hardening (setting) of cement will enclose soil as glue, but it will not change the structure of soil, Euro Soil Stab (2002). The hydration reaction is slow proceeding from the surface of the cement grains and the center of the grains may remain unhydrated, Sherwood (1993). Cement hydration is a complex process with a complex series of unknown chemical reactions, MacLaren and White (2003). However, this process can be affected by: • Presence of foreign matters or impurities. • Water-cement ratio. • Curing temperature. • Presence of additives. • Specific surface of the mixture. Depending on factors involved, the ultimate effect on setting and gain in strength of cement stabilized soil may vary. Therefore, this should be taken into account during mix design in order to achieve the desired strength. Calcium silicates, C3S and C2S are the two main cementitious properties of ordinary Portland cement responsible for strength development, Al-Tabbaa and Perera (2005) and Euro Soil Stab (2002). Calcium hydroxide is another hydration product of Portland cement that further reacts with pozzolanic materials available in stabilized soil to produce further cementitious material, Sherwood (1993). Normally the amount of cement used is small but sufficient to improve the engineering properties of the soil and further improved cation exchange of clay. Cement stabilized soils have the following improved properties: • Decreased cohesiveness (Plasticity) • Decreased volume expansion or compressibility • Increased strength. Table 2.4: Cement requirement by volume for an effective stabilization of various soils, Das (2011) Soil Type AASHTO Classification Unified Soil Classification System System A-2 and A-3 GP, SP and SW A-4 and A-5 CL, ML and MH A-6 and A-7 CL, CH
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Percent Cement by Volume 6-10 8-12 10-14
2.5.2 Lime Stabilization Lime provides an economical way of soil stabilization. Lime modification describes an increase in strength brought by cation exchange capacity rather than cementing effect brought by pozzolanic reaction, Sherwood (1993). In soil modification, as clay particles flocculates, transforms natural plate like clays particles into needle like interlocking metal line structures. Clay soils turn drier and less susceptible to water content changes, Roger et al (1993). Lime stabilization may refer to pozzolanic reaction in which pozzolana materials reacts with lime in presence of water to produce cementitious compounds, Sherwood (1993) and Euro Soil Stab (2002). The effect can be brought by either quicklime, CaO or hydrated lime, Ca (OH)2. Slurry lime also can be used in dry soils conditions where water may be required to achieve effective compaction, Hicks (2002). Quicklime is the most commonly used lime. The followings are the advantages of quicklime over hydrated lime, Rogers et al (1996). • Higher available free lime content per unit mass • Denser than hydrated lime (less storage space is required) and less dust. • Generates heat which accelerates strength gain and large reduction in moisture content according to the reaction equation below: CaO + H2O = Ca(OH)2 + Heat (65KJ/mol)…………………………………………………………………….………… . Quicklime when mixed with wet soils, immediately takes up to 32% of its own weight of water from the surrounding soil to form hydrated lime. The generated heat accompanied by this reaction will further cause loss of water due to evaporation which in turn results into increased plastic limit of soil i.e. drying out and absorption, Euro Soil Stab (2002) and Sherwood (1993). The effect can be explained for soil at a moisture content of 35% and plastic limit 25%. Addition of 2% lime will change the plastic limit to 40% so that the moisture content of the soil will be 5% below plastic limit instead of 10% above plastic limit (Sherwood, 1993). Sherwood (1993) investigated the decrease in plasticity as brought about in first instance by cation exchange in which cations of sodium and hydrogen are replaced by calcium ions for which the clay mineral has a greater water affinity. Even in soils (e.g. calcareous soils) where, clay may be saturated with calcium ions, addition of lime will increase pH and hence increase the exchange capacity. Like cement, lime when reacts with wet clay minerals result into increased pH which favors solubility of siliceous and aluminous compounds. These compounds react with calcium to form calcium silica and calcium alumina hydrates, a cementitious product similar to those of cement paste. Natural pozzolanas materials containing silica and alumina (e.g. clay minerals, pulverized fly ash, PFA, blast furnace slag) have great potential to react with lime.
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Lime stabilizations technology is mostly widely used in geotechnical and environmental applications. Some of applications include encapsulation of contaminants, rendering of backfill (e.g. wet cohesive soil), highway capping, slope stabilization and foundation improvement such as in use of lime pile or lime-stabilized soil columns, Ingles and Metcalf (1972). However, presence of sulphur and organic materials may inhibit the lime stabilization process. Sulphate (e.g. gypsum) will react with lime and swell, which may have effect on soil strength. Lime stabilization of heavy clays has been practiced in the road industry in many countries around the world. A study of lime stabilization of expansive soils in Sudan confirmed the technical viability of the treatment for use as road pavement materials. The factors, based on Elsharif (2001), that encourage the introduction or implementation of lime stabilization in Sudan are: • Highly expansive soils cover wide areas in Sudan. • The availability of raw materials in Sudan. • Encouraging results have been achieved in the laboratory. • The road network is expanding over extended areas of expansive subgrade. However, the following constraints are expected when implanting or using lime as stabilizer: • Difficulties of mixing specially in relatively wet climates. • Lack of experience and the need of skilled labors. • Poor production of hydrated lime in the available kilns and the use of expensive imported lime. But most of the above mentioned constrains may be overcome by good planning and stage implementation. Experts can be called for from abroad and consequently experience transfer will be acquired. Trail sections can be made their functional and structural conditions can be assessed and the expected promising results will encourage the construction of industries for lime production of high quality and low cost. So all reviewed road designs herein confirmed that it is a must to treat expansive subgrade with particular attention.
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Legend: 1) Clay or Silty clay. 2) Clayey Silt. 3) Silt Sand (Goz).
4) Lateritic Soils. 5) Silty Gravelly.
Fig 2.3: Sudan Soil Map, Elsharif (2001) 22
Table 2.5: Lime deposits in Sudan, Elsharif (2001) Location Jebel Aulia, N 5 ⁰ 5 ’, Sennar Area, N 5 ⁰ 5 ’- 5 E ⁰ ’Kosti Area Jebel Murat, N 20⁰ 0 ’ E Atbara Mabe, N 17⁰ 0’ E Durdeb Area, N 11⁰ 0’ E
Estimated Quantities E ⁰ ⁰ 0’, ⁰ ’
’
0⁰ ’ ⁰ 0’ ⁰0 ’
Maman Area, N 16⁰ 5 ’ E ⁰ 50’ Coastal Area, N 19⁰ 50’- 19⁰ ’ E 37⁰ 50’ – 37⁰ 0’ Elruseires Area Jebel Rashad Area N 11⁰ ’ E 5⁰ 5 ’ Elfasher Area
Not Measured. 1175 M ton. (Marble of CaCo3 = 98.6%) Not Measured (Marble CaCo3 = 64.8%) Not Measured (Marble CaCo3 = 96%) 60 M ton. (Marble of CaO = 52%) 17 M ton. (one of the two deposits) (Marble of Cao = 54% Not Measured (Marble of high quality) Not Measured Not measured (Marble of CaO = 56%) Not Measured (Marble of CaO = 54%) Not Measured (Two deposits of CaCo3 = 96%)
Table 2.6: Results of Lime Stabilized Expansive Clay Elsharif, (2001) Results
Name of Road Singa – Damazin (Km 56) Mujlad – Higlieg (Km 143) Namma – Abyei.
Lime % CBR% @ OMC Lime % CBR% @ OMC Lime % CBR% @ OMC
0 2.6 0 2.9 0 3.4
23
1 10.8 2 11.5 3 58.0
2 64.0 4 90.0 5 71.0
4 118.5 6 132.0 7 72.0
2.5.3 Fly Ash Stabilization: Fly ash is a byproduct of coal fired electric power generation facilities. It has little cementitious properties compared to lime and cement. Most of the fly ashes belong to secondary binders, these binders cannot produce the desired effect on their own. However, in the presence of a small amount of activator, it can react chemically to form cementitious compound that contributes to improved strength of soft soil. Fly ashes are readily available, cheaper and environmental friendly. There are two main classes of fly ashes, class C and class F, Bhuvaneshwari et al (2005). Class C fly ashes are produced from burning subbituminous coal. It has high cementing properties because of high content of free CaO. Class C from lignite has the highest CaO (above 30%) resulting in self-cementing characteristics. Class F fly ashes are produced by burning anthracite and bituminous coal. It has low self-cementing properties due to limited amount of free CaO available for flocculation of clay minerals and thus require addition of activators such as lime or cement. The reduction of swell potential achieved in fly ashes treated soil relates to mechanical bonding rather than ionic exchange with clay minerals, Mackiewicz and Ferguson (2005). However, soil fly ash stabilization has the following limitations, White (2005): • “oil to e sta ilized shall have less moisture content; therefore, dewatering may be required. • Soil-fly ash mixture cured below zero and then soaked in water is highly susceptible to slaking and strength loss. • “ulfu o te ts a fo e pa si e i e als i soil-fly ash mixture, which reduces the long term strength and durability.
Plate 2.2: Fly Ash used in this research 24
Table 2.7: The chemical properties of fly ash as reported by Abadi, (2014) CaO (%) Fly ash
18.52
MgO (%) 0.80
NaO (%)
K2O (%)
0.80
0.25
Fe2O3 (%) 1.08
SiO2 (%) 46.47
AL2O3 (%) Nd
SO3 (%) 0.03
2.6 Previous Investigations: Many researchers have been studied the stabilization of expansive soil; hence their searches have shown out promising results for such purpose and applications as well, quite often one more additives have been experienced around the world such as sand, silt, lime, fly ash, cement, etc.. Zumrawi, (2013) studied Expansive Soil Stabilization with Fly Ash to improve expansive soil as construction material using fly ash in varying percentages, he has carried out strength and swelling tests. The study results are summarized in the followings: • Stress- strain behavior of unconfined compressive strength showed that failure stress and strains increased by 106% and 50% respectively when fly ash content was increased from 0% to 25%. • When the fly ash content was increased from 0% to 25%, CBR improved by 47%. • The optimum fly ash content was found at 25% for both UCS and CBR tests. • The swelling potential of expansive soil decreases with increasing swell reduction layer thickness ratio. • The vertical movement of clay soils with cushioning material stabilizes after 3 cycles of swelling and shrinkage. • A fly ash content of 25% is recommended for strengthening the expansive subgrade soil. Mohammed (1983) reported that the lime-clay reaction takes place in two stages: • The first stage is cation exchange reaction whereas the sodium cations have exchange with calcium cations. This will reduce the clay particles water absorption capacity and thus reduce swelling potential. • The second stage happened after complete of the stage one. At this stage the lime reacts with the clay particles and produce cementitous material which produce the clay particles. The limeclay reaction depends on the soil menology. The lime more reactive with montmorillonitic clays less with illite and far less than carollite. Adam et al (2012) have studied the Effect of Hydrated Lime on Behavior of Expansive Soil as Subgrade of Flexible Pavement Structural System, by adding 2%, 4% and 6% of hydrated lime to an expansive soil cured within 24 hours and they had carried out a serious test as sieve analysis, 25
liquid limit, plastic limit and plasticity index as well as dry density, moisture content relationship also mechanical tests in term of and CBR test was conducted before and after adding the lime. Their results showed that the lime provides better physical properties in term of liquid limit, plastic limit and plasticity index and shows that the lime increases the CBR value to 52%, 27% and 44% when adding 2%, 4% and 6% percentages of lime, respectively, for untreated soil (CBR=1%). Also, the lime decreases swelling from 4% in untreated soil to 1.20%, 0.01% and 0.20% when adding 2%, 4% and 6% lime percentages, respectively. The design of pavement thickness shows that the adding of lime decreases the thickness from 92.5 cm when using untreated expansive soil as subgrade to 45cm, 35cm, and 35 cm when using 2%, 4%, and 6% percentages of lime respectively in stabilization of expansive soil as subgrade. The results suggest that the lime content 6% is optimum percentage were that given a highly strength, lowest swelling and small thickness of pavement. Elsharief et al (2013) studied Lime Stabilization of Tropical Soils from Sudan for Road Construction. They studied the effects of hydrated lime on the engineering properties of interest for road design and construction for three tropical clays, two highly plastic potentially expansive soils f o Repu li of “uda a d o e ed t opi al late iti soil from Republic of South Sudan. The effects of compaction energy on the material properties were studied. Also, the effect of salinity/sodicity on the plasticity and strength of lime stabilized swelling soils were studied. Their study results showed that lime efficiently reduces the plasticity of the three soils considered and that for the same increment of lime content the reduction in plasticity is higher for montmorillonitic clays compared to kaolinitic clays. The addition of lime to the three soils increased their maximum dry densities and reduced their optimum moisture content. Substantial improvement in the strength and compaction characteristics of lime stabilized tropical clays could be expected on increasing the compaction effort. The permeability substantially increased on adding the optimum lime content to the three soils. Lime increased the strength and stiffness of the treated soils and the amount of lime needed to improve lateritic clay soils is less than that needed to improve swelling soils. The resilient modulus test results indicated an increase in stiffness of the lime stabilized kaolinitic clay soils compared to montmorillonitic clays. The increase in salinity/sodicity resulted in decrease of plasticity and increase in strength for the natural untreated and lime treated sodic soil tested. Elsharief and Elhassan (2013) studied the effect of lime on the intrinsic swelling and shrinkage of clay soils from Sudan. They carried out laboratory testing, to study the effect of addition of hydrated lime on the intrinsic swelling and shrinkage to expansive soil samples from different areas in Sudan. They reported that the engineering properties of soil samples significantly improved with addition of lime, i.e. swelling and shrinkage decreased with increase in lime 26
content. The effective lime content to be added should be more than 2%. The addition of this effective lime content caused liquid limit to drop by 10% to 16% and plasticity index to drop by 40% to 50% of the untreated values. The free swell and linear shrinkage showed remarkable decrease on addition of the effective lime content. The mineralogical composition of the clays seemed to affect the response to lime addition. Abadi (2014) studied Fly Ash Utilization in Soil Stabilization. She performed experimental tests on expansive soil mixed with various percentages of fly ash and cement, she has noticed that clay soil has been improved because of additives. She suggested that 15% fly ash with 5% cement is the optimum ratio which clearly reduced clay plasticity. She used class F fly ash with 5% cement and achieved consistency limits, compaction and CBR tests. Pandian et al (2002) studied the effect of two types of fly ash, class F and class C, on the CBR characteristics of the expansive soil. The fly ash content was increased from 0% to 100%. Generally the CBR strength is contributed by its cohesion and friction. The CBR of expansive soil which consist predominantly of finer particles is contributed by cohesion. The CBR of expansive soil which consist predominantly of coarser particles is contributed by its frictional component. The low CBR of expansive soil is attributed to the inherent low strength, which is due to the dominance of clay friction. The addition of fly ash to expansive soil increases the CBR of the mix up the first optimum level due to the frictional resistance from fly ash in addition to the cohesion from expansive soil. Further addition of fly ash beyond the optimum level result in decrease up to 60% and then up to the second optimum level there is an increase. Thus the variation of CBR of fly ash – expansive soil mixes can be attributed to the relative contribution of frictional or cohesive resistance form fly ash or the expansive soil respectively. In type C fly ash also there is an increase of strength with the increase of fly ash content, here there will be additional puzzolonic reaction forming cementitious compounds resulting in good binding between expansive soil and fly ash particles. Phanikumar and Sharma (2004) studied the effect of fly ash on engineering properties (free swell index (FSI), swell potential, swelling pressure, plasticity, compaction, strength and hydraulic conductivity) of expansive soil through an experimental program. The fly ash was mixed together with expansive soil with varying fly ash content of 0%, 5%, 10%, 15%, 10% and 20% of dry weight basis, and they inferred that increase in fly ash content reduce plasticity characteristics and the FSI was reduced by 50% on the addition of 20% fly ash. The hydraulic conductivity decreases with an increase in fly ash content, due to the increase in maximum dry unit weight with an increase in fly ash content. Also with the increase of fly ash content there is a decrease in the optimum moisture content against an increase in the maximum dry unit weight, as well as increasing of fly ash content meet increasing either of compacting effort and shear strength. 27
Sertan Isik Cetiner (2004) studied stabilization of expansive soils by fly ash and desulphogypsum, from 0% to 30% to expansive soil, furthermore he used 0% to 8% lime (cured 7days and 28days) to see how efficient fly ash and desulphogpsum on expansive soil stabilization. A various tests were performed in his study and noticed that curing resulted in further reduction in swelling and further increase in rate of swell, also 25% to 30% of fly ash and desulphogpsum reduced swelling to comparable levels with lime stabilization.
Joseph Desire Muhirwa et al (2006) studied lime stabilization of expansive soils. They were used soil samples from Austin and Texas with high plasticity index. The main goal was to increase the bearing capacity of the soil and to reduce volumetric fluctuations of it. They concluded that 6% lime provided the best results. However, 4% provided nearly similar results and could be more economical. And 4% was determined to be the most effective additi e fo sta ilizatio of Austi ’s e pa si e soil. They recommended for future researches that lime could be combined with other additives (such as cement) for improved performance. Fattah et al (2010) studied treatment of expansive soil with different additives to improve the soil. They took soil samples from north of Iraq. Samples were treated by four types of additives cement, steel fibers, gasoline fuel and injection by cement grout. They noticed that the treatment of expansive soil with 5 % of cement or steel fibers, or the injection with the cement grout resulted in the better improvement, while 4 % of gasoline oil is sufficient for the optimum treatment by this material. And the compression index (Cc) and swelling index (Cr) for the treated soil decreased. The angle of internal friction was not affected by the treatment due to the fact that the cement has a larger surface area than the soil. Yohannes Argu (2008) studied stabilization of light gray and red clay subgrade soil by SA-44/LS40 chemical and lime. He took a light grey and a red clay soil samples taken from within Addis Ababa. He carried out laboratory tests of soaked CBR and CBR swell tests, swelling pressure test, Atterberg limit tests, swell percent test and free swell tests. The treated samples were cured for fourteen days. He noticed that applications of SA-44/LS-40 chemical alone reduced swelling pressure and improved soaked CBR value. Applications of lime alone increased soaked CBR value and reduced swelling pressure. Applications of the chemical with lime together resulted in more increases in soaked CBR value and reduced swelling pressure of both soils. So the application of the chemical with lime was more suitable for both samples. Buhler and Cerato studied stabilization of Oklahoma expansive soil by lime and class C fly ash, their study was focused on using the liner shrinkage test to quantify the amount of shrinkage 28
arrest in high plasticity soil. They had shown that their study was important because most of the native soil there was expansive soil, they noticed that addition of lime or fly ash helped to arrest the shrinkage and swelling behavior of soil. They have taken four soil samples to show shrinkage variability within soil group with the addition of lime and class C fly ash. So they had noticed: • Soils classified within the same AASHTO group had varying shrinkage characteristics. • Lime and fly ash reduced the liner shrinkage; however, the addition of lime arrested the shrinkage at almost twice greater degree than the same percentage of class C fly ash. • The cost benefit of possible future use class C fly ash in road bed stabilization is to reduce lime amount. • The liner shrinkage decreased from approximately 4 to 7% with the addition of 5% lime, while the liner shrinkage only decreased 1 to 2% with the addition of 5% class C fly ash. • The specific gravity of lime is 5.4 times smaller than that of fly ash, therefore the volume of lime added is significantly greater and the workability of the lime and soil decreased at a much lower additive percentage than the workability of the fly ash and soil. • The shrinkage arrest continued up to 10% lime additive, there was a decrease in strength after only 4% added lime. Ganja and Jagarlamudi (2012) studied the utilization of GBFS and fly ash to stabilize the expansive soil for subgrade embankments. They were studied the influence of industrial waste like GBFS (Granulated Blast Furnace Slag), fly ash on compaction properties of expansive soil. In their study, detailed laboratory investigations were taken, in which GBFS in different proportions of locally soil and fly ash were mixed and subjected to different tests of Atterberg limits and strength characteristics of various mixes. They had shown that black cotton soils of India have liquid limit values ranging from 50 to 100%, plasticity index ranging from 20 to 65% and shrinkage limit from 9 to 14%. And they had concluded the followings: • It was observed that the 20% fly ash gives optimum CBR value for the first layer of the embankment. • It was observed from the compaction test results that the CBR value was optimum for the 5% fly ash + 80% GBFS, and it can be used as subgrade. • It was observed that the CBR value was optimum by adding 5% fly ash with the GBFS. • It was noticed that the cohesion of the 5% fly ash + 80% GBFS has been increased by 716% with the addition of 15% expansive soil. • It was noticed that the angle of internal friction of the 5%fly ash + 80% GBFS has been decreased by 20% with the addition of 15% expansive soil. Muntohar (2002) studied utilization of uncontrolled burnt rice husk ash in soil improvement. 29
He was conducted a series laboratory tests. These tests were carried out individually or in a combination in which the Rice Husk Ash (RHA) content were varied from 7.5%, 10% and 12.5%, and lime content from 2%, 4%, 6% and 10%. He had showed that lime – rice husk ash decreased the swell of expansive soil and improved its strength and bearing capacity. Besides he had noticed: • Lime and RHA reduced the liquid limits while the plastics limits increased so as a results plasticity indexes reduced. • Swelling potential of expansive soil diminished with addition of admixtures and the compressibility of soil reduced with blend of lime and RHA. • The optimum moisture content moved to wet side, and the maximum dry density enhanced marginally, this was indicated that the additives especially RHA imbibe much water to attain maximum dry density. • The CBR values enhanced. 10% lime content produced brittle failure under compression. Whereas, soil treated with combination of RHA and lime revealed a ductile behavior, but the strength increased marginally.
30
Chapter Three Experimental Work 3.1 Introduction This chapter is concern about the experimental work of the study. Expansive soils were taken from three different regions in Sudan. The laboratory tests conducted on the studied samples include preliminary tests, swelling tests and strength tests. The tests data obtained were analyzed using excel program. The results of the study were discussed to verify the validity of these results. 3.2 Materials used Three soil samples from different areas in Sudan were collected for this study. The soils were obtained from Soba in Khartoum, Madani in Gezira and Gedarif. As previously, reviewed in chapter two, that lime and fly ash are efficient to stabilize the expansive soil. The lime material used in this study was obtained from Kassala. The fly ash material was collected from Gary Electrical Station in Khartoum North. Experimental tests were conducted untreated samples and treated samples. 1. Soba The soil sample taken f o “o a Al-lao ta i Kha tou state he e lo ated south of Khartoum about 20 Km, west of Madani – Khartoum road. The soil was taken from depth 0.5 to 1.0 m of the pit hole. Its physical appear as lightly brown, sometimes dark gray of medium slipperiness. It seems that it contains silt materials. 2. Madani The soil sa ple as take f o Al adi a A a where located west of Madani city in Gezira state, in the middle area between Manadni- Almanagil. The soil sample was taken from depth 0.5 to 1.0 m of the pit hole. The soil physical appear as dark brown and stiff clay particles. Madani soils famous as high plasticity and weak strength. 3. Gedarif The soil sample was taken from a please near Gedarif city. The soil collected depth 0.5 to 1.0 m of the pit hole. This soil is dark black and stiff clay. Gedarif soils are also known as high plastic clay and weak strength.
31
: Soba
: Madani
: Gedarif
Fig 3.1: Sudan and South Sudan map showing the locations of the soils used in this study
32
Plate 3.1: The appearance of the clay soil at Soba in Khartoum
Plate 3.2: The soil sample taken from Madani in Gezira
Plate 3.3: The soil sample obtained from Gedarif 33
3.3 Laboratory Testing 3.3.1 Sieve Analysis The sieve analysis test is a main test in soil classification according to soil particle sizes. The soil can be stone, gravel, sand, silt and clay. The stones are the largest particle sizes while clay is the finest. The soil in nature may contain more sizes such as sandy silt or silty clay, etc. This test as mechanical analysis test carried out on course soils, and sedimentation test carried out on fine soils. Testing Procedure Samples were triturated first then air dried, then subjected to sieve test by manually shaking in accordance with British standard. The grain size distributions were plotted herein and shown in the appendix.
Plate 3.4: The set of sieves used in testing
34
3.3.2 Atterberg Limits It’s a k o ledge of the a g of oistu e o te t o e hi h a soil ill e hi it a e tai consistency is often beneficial, cause the behavior of soil is often related to the amount of water contained in the soil mass. Therefore a knowledge of the soil consistency, or relative ease with which the soil can be deformed, is important in classifying a soil type or predicting how the soil might be perform when used as a construction material. Atterberg limits are defined as: 1. Shrinkage limit: The moisture content at which no further volume changes occurs with a further reduction in moisture content, or it can be defined as the moisture content representing the amount of water required to fill the voids of a given cohesive at its minimum void ratio obtained by drying. 2. Plastic limit: The moisture content at which a thread of soil just begins to crack and crumble when rolled to a diameter of 3 mm. 3. Liquid limit: The moisture content at which a 2 mm wide groove in a soil pat will close for a distance of 1.2 mm, when dropped 25 times in a standard brass cup, falling 10 mm each time at a rate of 2 drops per second, while in a standard liquid limit device. Those limits are used as parameters by Holtz and Gibs (1956) to classify soils based on its plasticity (Table 2.1). • Plasti it I de : PI : This i de p o ides a easu e of a soil’s plasti it , hi h is the a ou t of ate that ust e added to change a soil from its plastic limit to its liquid limit. The plasticity index is defined as: PI = LL – PL The plasti it i de is used f e ue tl to p edi t a soil’s elati e a ilit to u de go olu e changes (if expansive soil or not). • Li uidit I de o ate – plasticity ratio B; This index can provide a clue as to the condition of the in situ soil. A high positive value indicates that the natural moisture content m.c, is very close to the liquid limit and it may even exceed the liquid limit, also high positive value of liquidity index indicates the soil can be expected to have a low remolded shear strength. On the other hand a low or negative value implies that the soil may be desiccated or maybe, over consolidated. Some soils do not possess sufficient plasticity to permit performing either the plastic limit and liquid limit tests, or even both tests successfully. When one of test or the other cannot be pe fo ed, the soil is said to e o -plasti o NP , this is usuall o u s he the soil is 35
extremely sand. Consequently, when testing these types of soil, the simpler plastic limit test should be performed first. For those few instances when the plastic limit is equal to, or even greater that the liquid limit, the soil should be reported as NP.
Plate 3.5: Casagrande device and tools used for liquid limit measurement Testing Procedure Samples were air dried then passed through sieve no. 40, distilled water added to bring the soil to a suitable consistency. Then the moist soils were kept well to prevent evaporation and allowed to cure for a period of 24 hours. In this study 28 tests were performed on samples before and after treatment as shown in appendix. The plastic limit tests were performed in this study according to British standard, and the results with calculations were shown in tables in appendix. The liquid limit tests were performed using Casagrande device and the results were shown in appendix.
36
3.3.3 Compaction Test The purpose of compaction test is to determine the optimum moisture content that at which the maximum density of the soil can be achieved. Increasing the density of soil is often desirable for increased soil shear strength, decreased future settlement, and decreased soil permeability. Eight trails tests were performed in this study, compaction for soils and compaction for soils before and after treatment as shown in appendix. Procedures followed here to facilitate the compaction tests were standard compaction according to ASTM. The dry density versus moisture content was plotted, and the curve of the best points was fitted, the point of the greater density reported as the optimum moisture content whichever occurring at the apex of the curve. Plots and tables were noted in the accompany appendix.
Plate 3.6: The apparatus and tools used for sample preparation in laboratory
37
Plate 3.7: The compaction test apparatus and tools used in the study
38
3.3.4 The California Bearing Ratio (CBR) The California Bearing Ratio test was originally developed by the California Division of Highways under Porter (1938) for the design of highway pavement thicknesses and was put forward as a standard test to the American Society for Testing Materials by Stanton (1944). The C.B.R. tests here were carried out at density and moisture content which related by the compaction curve to bear some relationship to that moisture content can be found in the soil in situ. In this study both soaked and un-soaked CBR were conducted. Testing Procedure The soil, compacted in the mold, was placed in the testing machine with the required number of surcharge weights on surface. The plunger was seated on the surface, using a total seating load of 10-Ib., which was included the weight of the plunger. Load and penetration gauges were then set at zero, and the test started. The plunger was pushed into the sample at a uniform rate of 0.05-in per minute. Readings of the load were taken every 25 division of an inch. Specimens of the soil were taken from the top, bottom and middle of the sample, and the average moisture content was measured.
Plate 3.8: The CBR test machine used in the study 39
Plate 3.9: The jack used in releasing the sample after CBR test
40
3.3.5 Free Swell The determination of free swell index of expansive soil helps to identify the potential of a soil to swell, which might need further detailed investigation regarding swelling and swelling pressures under different field conditions. The highly plastic clay normally will have very high swelling potential (very high degree of expansion). The free swell tests performed herein were accordance to British standard. Testing Procedure The testing procedure followed here was according to BS 1377 (1990) standard. 42 trails were achieved successfully in this study and results are shown in appendix.
Plate 3.10: The cylinders used the free swell test
41
3.3.6 Swelling Pressure Test The oedometer test is kind of soil test that investigation to measure the consolidation properties. Oedometer tests are performed by applying different loads to a soil sample and measuring the deformation. Oedometer tests are designed to simulate the one-dimensional deformation and drainage conditions that soils experience in the field. To simulate these conditions, rigid confining rings are used to prevent lateral displacement of the soil sample. To better simulate one-dimensional strain, a diameter-to-height ratio in the sample of 3:1 or more is used. Because the process of consolidation involves movement of water out of soil, it is important to prevent any drying of the soil. The testing method covers three alternative measurements of free swell, swelling pressure, and the magnitude of one-dimensional swell or heave of compacted cohesive soils. The test method can be used to measure the magnitude of one-dimensional wetting-induced swell under different vertical (axial) pressures, as well as the magnitude of swelling pressure and the magnitude of free swell. Testing Procedure The testing procedure followed in this study was according to BS 1377 (1990) standard. 8 trails were achieved successfully in this study for soil swelling determination and results are shown in appendix.
Plate 3.11: A sample mounted on consolidation apparatus during the swelling test 42
3.3.7 Unconfined Compressive Test A method of measuring the unconfined compression strength of a 1.5in diameter via 3in height soil specimen using the portable unconfined compression apparatus, the test carried out is an un-drained test, formerly called an immediate test; it is restricted to predominantly clayey soils.
Plate 3.12: The portable unconfined compression strength test machine used in the study In this study eight trails were conducted to unconfined compression test according to BS 1377 (1990) standard, using the compaction dry density and moisture content. Unconfined compression strength was determined as stress which caused the failure divided by area of sample calculated at failure.
43
3.4 Data Analysis: The results of the preliminary tests (grain size analysis and Atterberg's limits test) as well as the strength tests (compaction, California bearing ratio and unconfined compression tests) beside swelling tests for pre-treatment soils are hereby presented. Table 3.1: The tests results for the studied samples pre-treatment Property
Medani soil
Gedarif soil
Gravel (%) Sand (%) Silt (%) Clay (%) Liquid Limit. Plastic Limit. Plasticity Index. OMC. (%) MDD (gm/ cm3) CBR (%) Free swell (%) Swell Pressure (Kg/cm2) Unconfined Compression Strength (KN/m2)
0 13 22 65 69 34 35 24 1.486 2.6 120 17
0 5 24 71 78 38 40 26 1.400 2.54 188 28.5
606
390
44
The results of Atterberg's limits and swell percent tests for Medani and Gedarif soils stabilized with lime and fly ash are presented in tables 3.2 and 3.3 below. Table 3.2: Atterberg's limits and swell percent tests results for Medani soil stabilized by lime and fly ash Lime (%)
Fly Ash (%)
0 3 5 8 12 15 3 5 8 12 15 3 5 8 12 15 0 0 0 0 0
0 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 20 25 30 40
LL
PL
PI
69 74 65.5
34 35 52.4 21.6 51 14.5 None Plastic None Plastic None Plastic 68 43.2 24.8 60.2 45.9 14.3 None Plastic None Plastic None Plastic 61.5 50.1 11.4 None Plastic None Plastic None Plastic None Plastic 65.4 41.2 24.2 63.6 42.3 21.3 62.1 43.2 18.9 62.6 45.5 17.1 69.4 43.8 25.6
45
Free Swell (%)
Free Swell After shrinkage (%)
120 130 125 120 105 95 90 80 70 65 55 80 75 65 60 55 165 150 145 130 80
60 40 10 0 -10 60 55 0 -5 -5 40 40 -5 0 0 -
Table 3.3: Atterberg's limits and swell percent tests results for Gedarif soil stabilized by lime and fly ash Lime (%)
Fly Ash (%)
0 3 5 8 12 15 3 5 8 12 15 3 5 8 12 15 0 0 0 0 0
0 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 20 25 30 40
LL
PL
PI
78 70.9 69.6
38 40 49.2 21.7 56 13.6 None Plastic None Plastic None Plastic 79.9 51.5 28.4 None Plastic None Plastic None Plastic None Plastic 74.9 50.3 24.6 None Plastic None Plastic None Plastic None Plastic 76.6 45.4 31.2 73.8 52.3 21.5 73.9 54.1 19.8 73.5 53.2 20.3 81.4 53.7 27.7
46
Free Swell (%)
Free Swell After shrinkage (%)
188 150 140 125 115 110 14 80 80 50 60 60 90 80 78 65 240 210 185 173 110
90 80 50 15 5 20 20 20 10 10 20 15 10 -10 -10 -
From the summery of tests results presented in tables 3.2 and 3.3 above, it can be observed that either lime or fly ash or both together had reduced both soils swelling and plasticity, whilst, addition of 5% lime, 8% lime + 5% fly ash and 5%lime + 10% fly ash to Medani soil and 8% lime, 5% lime + 5% fly ash and 5%lime + 5% fly ash to Gedarif soil were just reduced soils plasticity and swelling, therefore those percentages of lime and fly ash were considered as appropriate to treat the soils, henceforth, they were proceeded to further testing below. Table 3.4: The tests results for Medani soil stabilized by optimum lime and fly ash content Property PI Free Swell (%) OMC (%) MDD (gm/cm3) Un-Soaked CBR (%) Soaked CBR (%) CBR Swell (%) Swell Pressure (Kg/cm2) UCS (KN/m3)
Natural Soil 35 120 24 1.486 2.6 -
8% lime + 0% fly ash 00 11 24 1.48 70 151 0.08
8% lime + 5% fly ash 00 10 30.5 1.418 36 114 0.11
5% lime + 10% fly ash 00 14 30.1 1.41 31 77 0.03
17
00
00
00
606
1033
1090
1152
Table 3.5: The tests results for Gedarif soil stabilized by optimum lime and fly ash content Property PI Free Swell (%) OMC (%) MDD (gm/cm3) Un-Soaked CBR (%) Soaked CBR (%) CBR Swell (%) Swell Pressure (Kg/cm2) UCS (KN/m3)
Natural Soil 40 188 26 1.4 2.54 -
8% lime + 0% fly ash 00 15 29.5 1.4 60 111.5 0.09
5% lime + 5% fly ash 00 12 27.2 1.418 45 77.4 0.06
5% lime + 10% fly ash 00 11.5 29.5 1.385 36 72 0.13
28.6
00
00
00
390
1840
1506
1151
47
Laboratory tests results in this study proved that addition of either lime only or fly ash only were able to reduce soil swelling gradually. Nevertheless tests showed that lime has more affect than fly ash as 12% to 15% lime prevent soil swelling, whilst up to 40% fly ash was just reduced swelling about 35% as shown in figures below. The figures below are plotted -based on tests results- to explain the relationship of free swell versus additives percent and plasticity index versus additives percent. Figures 3.2 and 3.3 show the effect of each lime and fly ash stabilizers on free swell. The free swell decreases on both soils are noticed with increases of additives. The percent of fly ash added is more than lime percent required. The free swell values are higher when adding fly ash. 180 160 Lime Only
140
Fly Ash Only
Free Swell (%)
120 100 80 60 40 20 0 -20
0
5
10
15
20
25
30
35
40
Additive (%) Fig 3.2: Free swell versus additives percent relationship for Medani soil
48
45
300 Lime Only 250
Free Swell (%)
Fly ash Only 200
150
100
50
0 0
5
10
15
20
25
30
35
40
45
Additives (%) Fig 3.3: Free swell versus additives percent relationship for Gedarif soil Figures 3.4 and 3.5 show the effect of lime with fixed fly ash content on free swell. It is clear that as lime and fly ash contents increases the free swell reduced. 70 60 Fly Ash 5%
Free swell (%)
50
Fly Ash 10%
40 30 20 10 0 0 -10
2
4
6
8
10
12
14
Lime (%) Fig 3.4: Free swell versus Lime percent relationship for Medani soil 49
16
25 Fly Ash 5%
20
Fly Ash 10%
Free Swell (%)
15 10 5 0 0
2
4
6
8
10
12
14
16
-5 -10 -15
Lime (%) Fig 3.5: Free swell versus Lime percent relationship for Gedarif soil
Figures 3.6 and 3.7 show the modifications on plasticity index meets increases of lime only and fly ash only. The percent of fly ash added is more than lime percent required. It is noticed that when fly ash content exceeded 30% the plasticity index increased. 40 Lime Only
35
Fly ash Only
Plasticity Index
30 25 20 15 10 5 0 0
5
10
15
20
25
30
35
40
Additives (%) Fig 3.6: Plasticity index versus additives percent relationship for Medani soil 50
45
45 40 Lime Only
Plasticity Index
35 Fly ash Only
30 25 20 15 10 5 0 0
5
10
15
20
25
30
35
40
45
Additives Percent Fig 3.7: Plasticity index versus additives percent relationship for Gedarif soil Figures 3.8 and 3.9 show the effect of lime with fixed fly ash content on plasticity index. It is clear that when lime and fly ash increase the plasticity index reduced. 30 Fly Ash 5%
Plasticity Index
25
Fly Ash 10%
20 15 10 5 0 0
2
4
6
8
10
12
14
Lime (%)
Fig 3.8: Plasticity index versus lime percent relationship for Medani soil 51
16
30 Fly ash 5% 25
Plasticity Index
Fly Ash 10% 20
15
10
5
0 0
2
4
6
8
10
12
14
16
Lime (%) Fig 3.9: Plasticity index versus lime percent relationship for Gedarif soil Figures 3.10 and 3.11 show the moisture content- dry density relationship of soil samples pretreated and treated soil samples with different contents of additives. It can be seen that as the fly ash content increases, the maximum dry density decreased and the optimum moisture content increased. 1.5 Soil Only
1.48
Soil + 8% Lime
Dry Density (gm/cm3)
1.46
Soil + 8% Lime + 5% Ash
1.44
Soil + 5% Lime + 10% Ash
1.42 1.4 1.38 1.36 1.34 1.32 1.3 10
15
20
25
30
35
Moisture Content (%) Fig 3.10: Dry density versus moisture content relationship for Medani soil 52
40
1.44
Soil Only Soil + 8% Lime Soil + 5% Lime + 5% Ash Soil + 5% Lime + 10% Ash
Dry Density (gm/cm3)
1.42 1.4 1.38 1.36 1.34 1.32 1.3 1.28 1.26 5
10
15
20
25
Moisture Content (%)
30
35
40
Fig 3.11: Dry density versus moisture content relationship for Gedarif soil 3.5 Discussion: The summery of the tests results showed that both of lime and fly ash improved the engineering properties of expansive soil in general. Figures 3.2 and 3.3 show that either lime or fly ash was reduced the soil swelling gradually. Nevertheless lime has more effect than fly ash. 12% to 15% lime were completely prevented soil swelling, whilst up to 40% fly ash was just reduced swelling by almost 37%. Adding 3% lime to soil seems to decrease both soils studied by 50%. Moreover when adding fly ash and lime together, it was observed that fly ash decreased the amount of lime required to prevent soil swelling completely, as shown in table 3.7 and fig 3.12 below. Table 3.6: The stabilizers effect on free swell for the studied soils Additives (%)
Decrease in free swell for Medani soil (%)
Decrease in free swell for Gedarif soil (%)
3% Lime 5% Lime 12% Lime 3% Lime + 5% Fly ash 8% Lime + 5% Fly ash 3% Lime + 10% Fly ash 40% Fly ash
50% 67% 100% 50% 100% 67% 33%
50% 58% 95% 89% 89% 89% 42%
53
Fig 3.12: Free swell versus additives percent relationship for Medani and Gedarif soils Both soils were demonstrated improvement when mixed with additives. The lime was sufficient to prevent soil swelling, as shown in figure 3.13 below.
Fig 3.13: Swelling pressure versus additives percent relationship for Medani and Gedarif soils
54
The laboratory testing performed in this study indicated that the additives used were able to reduce the soil plasticity. 8% lime was sufficient to reduce the soils plasticity. The figures 3.6, 3.7, 3.8 and 3.9 show the effect of additives on plasticity. Table 3.7: The stabilizers effect on plasticity index for the studied soils Additives (%)
Decrease in plasticity index for Medani soil (%)
Decrease in plasticity index for Gedarif soil (%)
3% Lime 5% Lime 8% Lime 3% Lime + 5% Fly ash 5% Lime + 5% Fly ash 3% Lime + 10% Fly ash 40% Fly ash
38% 59% 100% 30% 59% 67% 27%
48% 66% 100% 29% 100% 39% 31%
A great improvement in soil CBR have been recorded when the soils mixed with 8% lime. The CBR was greatly increased on both soils. But it was noticed that when adding fly ash to the soils and lime mixture, CBR seems to be decreased. When soil mixed with 8% lime and 5% fly ash, CBR was decreased by about 28%, as shown in figure 3.14 below.
Fig 3.14: California bearing ratio versus additives percent relationship for Medani and Gedarif soils compacted at the optimum moisture content. 55
Gedarif soils demonstrated a little more response on UCS than Medani soils when mixed with additives. When adding 8% lime to both soils, Gedarif soils showed more increases in UCS than Medani soils. This evidenced by that Gedarif soils have more clay content while Medani soils contain more sand (based on sieve analysis tests, Table 3.1) as lime has more reaction with clay particles. It was recognized that decreases of lime amount was followed by decreasing in UCS even if fly ash added.
Fig 3.15: Unconfined compression strength versus additives percent relationship for Medani and Gedarif soils compacted at optimum moisture content.
56
Chapter Four Conclusion 4.1 Summary: The performance of pavement depends upon the strength of subgrade materials, whereas stable and strong subgrade helps to produce a long-lasting pavement. But when subgrade soils are expansive soils, extensive methods have been studied and practiced to solve the expansive soil problems brought to pavement. An effective and economic method studied in this research, the treatment using lime and class F fly ash as stabilizers. This study based on experimental testing. Initially, the soils were tested to find out their conformability to the standard specifications. The results obtained from these tests, as shown in Table 3.1 were compared with the standard specifications of AASHTO. For the soils not comply with specifications, chemical stabilization was carried out to improve their failed properties. Experimental trails were carried out by adding percentage of lime and fly ash to expansive soil. The fly ash and lime are mainly added to reduce the plasticity and to increase the strength (CBR) of the expansive soil. The mixture specimens were prepared using lime as stabilizer varying from 3% to 15% by weight respectively and fly ash added from 15% to 40%. The trails started with the minimum value of the stabilizer, 3% by weight and then gradually increased till attained the target specified characteristics of subgrade soil. Grain size analysis tests for natural soil shown that samples tested were clayey soil. And Atterberg limits tests results for natural soil samples shown that Medani soil was high potential for swelling while Gedarif soil was very high potential for swelling according to classification of Holtz and Gibbs, 1956. But when adding 8% and more of lime only or 5% and more of lime and fly ash, samples were completely became none plastic soil. Natural soil samples demonstrated very weak properties measured by strength tests, (CBR and UCS). When the samples treated by 8% lime only a great improvement was noticed. It is observed that when fly ash injected to treatment formula, CBR of mixture has been decreased from that obtained by adding lime only. Both natural soil samples were demonstrate high swell percent and swell pressure whereas Gedarif soil was high potential for swelling according to swelling tests results provided in this study. Usage of lime and fly ash were decreased swell percent and swelling pressure completely.
57
4.2 Recommendations: 4.2.1 Recommendations for Public Authority: As clayey soils cover large areas in Sudan as well as all over the world and it is quite known form practical investigations and previous studies the huge cost delivered to roads due to clayey soils upon heave and shrinkage behavior. Therefore many methods have been practiced and studied to solve clayey soils problems. Chemical treatment maybe the suitable choice to Sudan and similar countries upon its low cost if compared with other treatment methods such as removal of subgrade, on the other hand chemical treatment may be effective in urban areas. As clayey soils demonstrate a large volume changes related to differential in moisture content which loss a uniform support to roads pavement, following recommendations are suggested to Public Authorities concern constructing roads: • To onduct more studies to determine the extent of expansive soils. • The suggested desig guideli es a e uite i po ta t that ill help oad e gi ee s i Sudan to make appropriate design for roads constructed on clayey soils. • The design parameters should include traffic loading, strength and swelling potential of subgrade soils. • It is e o e ded to e o e the su fa e of atu al e pa si e soil as deep as possi le a d treat the expansive subgrade up to CBR not less than 10%. • To achieve adequate drainage, proper surface slopes in both longitudinal and transverse directions should be maintained in the subgrade, subbase and base layers. Due to availability of both lime and fly ash in Sudan, usage of them have been investigated in this study as soil stabilizers and they had shown out the promising results for such applications. In Sudan there is limited use of fly ash in construction applications despite it is great availability produced from coal combustion used in electrical production stations, it is stockpiled and landscaped, causing serious environmental impact. Therefore it was used in this study as soil stabilizer, and Public Authorities are requested to encourage more studies concern fly ash applications for such projects due to dual benefits can ensued, to safe environment first then to help and reducing cost spent on subgrade stabilization. It was proved that lime has a great affect to stabilize clayey soils. Since many roads constructed on expansive clay such as Alazhari road, Alarda road, Omack road and many more in all over Sudan, and its face many expansion problems, therefore Public Authorities are recommended to take such studies for road construction, and roads designers are recommended to take hazards of clayey soil on mined in every step on designing roads.
58
4.2.2 Recommendations for Future Researches: This research is an extension of similar studies concern expansive soil stabilization chemically. Experimental geotechnical testing shows respectable results of the capability of lime and fly ash to stabilize the expansive soil. Future researchers are recommended to study the following: • To find criteria for evaluating the environmental effects of chemical stabilizers. • To look for further chemical stabilizers may be useful and effective. • To apply such studies on fields for further data analysis. • Samples used in this research are two types of expansive clay, high and very high expansive, and so, influence of additives was little different. Other types of expansive clay are recommended to be included in future researches. • Since lime is cured and strengthen regularly, a time diagrams for soil testing are recommended for future researches to determine treated soil properties based on lime curing. • Fly ash used in this study was class F, hence there is another type of fly ash, class C, and so future researches are recommended to include both types.
59
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[18] Karin Axelsson, Sven-E ik Joha sso , Ro A de sso , “ta ilizatio of O ga i “oils Ce e t a d Puzzola i Rea tio s , “ edish Deep “ta ilizatio Resea h Ce t e /o “ edish Geotechnical Institute SE-581 93 Linkoping, Sweden, ISSN 1402-2036, July 2002. [19] Lee D. Jones and Ia Jeffe so , I stitutio of Ci il E gi ee s Ma uals se ies. Chapte C5- E pa si e “oil , “o iet of Ci il E gi ee s, Resto , Vi gi ia, 005. [20] Miki H., Iwabuchi J., and Chida “., Ne “oil T eat e t Methods i Japa , Tok o, Japan, 2005. [21] Mohammed A. M. (19 , Effe t of e e t o s elli g pote tial o “uda ese la k otto soil . M.“ . thesis, BRRI, U i e sit of Kha tou . [22] Moha ed Nu Ada Ah ed, T eat e t Alte ati es fo E pa si e “oils as Road “u g ade , M.Sc. Submitted to Alzaeem Alazhari University, Sudan, 2006. [23] Moha ed Y. Fattah, Fi as A. “al a a d Bestu J. Na ee a , T eat e t of E pa si e “oil Usi g Diffe e t Additi es , U i e sit of Te h olog , Baghdad, I a , University of Malaya, 50603 Kuala Lumpur, Malaysia , University of Koya, Koya-Erbil, Iraq, 2010. [24] Mu toha A. “., Utilizatio of U o t olled Bu t Ri e Husk Ash i “oil I p o e e t , University of Malaya, ISSN 1410-9530 50603, Kuala Lumpur, 2002. [25] National Highway Institute - Federal Highway Administration - U.S. Department of T a spo tatio , Geote h i al Aspe ts of Pa e e ts , Pu li atio No FHWA NHI-05-037. Washington, D.C.USA, May 2006. [26] O'Flahe t , edited C.A., High a s the Lo atio , Desig , Co st u tio a d Mai te a e of Road Pa e e ts , th Ed. , O fo d, Butte o th-Heinemann, ISBN 978-07506-5090-8, 2002. [27] Pha iku a B.R. a d “ha a, Effe t of Fl ash o E gi ee i g P ope ties of E pa si e soil , Jou al of Geote h i al a d Geoe i o e tal E gi ee i g, Vol. 5 0, No. , pp. 767, July 2004. [28] Paige-Green P., Deali g ith Road “u g ade P o le s i “outhe Af i a , The 5 th International Conference of International Association for Computer Methods and Advances in Geo-mechanics (IACMAG) Goa, India, 2008. [29] Peter H May, The Identification and Treatment of Expansive Clay Sub-soils , Technical Paper, May Associates, April 2007. [30] Roge s a d Ma ti , High a e gi ee i g , O fo d, UK: Bla k ell “ ie e, ISBN 978-0632-05993-5, 2002. [31] Russell L. Buhle a d A B. Ce ato: “ta ilizatio of Oklaho a E pa si e soil Usi g Li e a d Class C Fl ash , University of Oklahoma, Norman, OK 73019. [32] “a ud a Ja aseke a, “ta ilizi g Volu e Cha ge Cha a te isti s of E pa si e “oil Usi g Ele t o ki eti s: A La o ato Based I estigatio , U i e sit of Balla at, Balla at, Vi to ia, Australia. [33] SertanIsik Cetine , “ta ilizatio of E pa si e “oils Ca i ha Fl Ash a d Desulphog psu , M“ . “u itted to the Middle East Technical University, Jan 2004. 61
[34] Shamrani M. A., Mutaz E., Puppala A. J. and Dafalla M. A., Cha a te izatio of P o le ati E pa si e “oils f o Mi e alogi al a d “ ell Cha a te izatio “tudies , American Society of Civil Engineers, Orlando, Florida, United States, 2010. [35] Sridharan A., and Prakash K., Classifi atio p o edu es fo e pa si e soils , Jou als Department, Institution of Civil Engineers, pp 12075, pp 235-240, Oct 2000. [36] Tom V. Mathew and K. V. Krishna Rao, Introduction to Highway Engineering , Chapte 2, pp. 2.1 - 2.7, NPTEL May 24, 2006. [37] Van der Merwe D. H., The P edi tio of Heave from the Plasticity Index and Clay F a tio of “oils , “outh Af i a I stitutio of Ci il E gi ee s, 5 . [38] Venkatesh Ganja and Venkatesh Jagarlamudi, A La o ato “tud o the Utilizatio of GBF“ a d Fl Ash to “ta ilize the E pa si e “oil fo “u g ade E a k e ts . U i e sit College of Engineering, Jntuk Kakinda, India, ISSN 0975-5462, Vol. 3, Nov 2011. [39] Vinay Agrawal and Mohit Gupta, Expansive Soil Stabilization Using Marble Dust , International Journal of Earth Sciences and Engineering, ISSN 0974-5904, Volume 04, No 06 SPL, pp 59-62, October 2011. [40] Wa e, M., Moha ed, a d Elfatih, Co st u tio o E pa si e “oils i “uda , Jou al of Performance of Constructed Facilities, Vol. 110, No. 3, pp. 359-374, 1984. [41] Yoha es A gu, “ta ilizatio of Light G a a d Red Cla “u g ade “oil Usi g “A-44/LS0 Che i al a d Li e , M“ . “u itted to Addis A a a U i e sit , Ja 00 . [42] )u a i M. M. E., Pa e e t Desig fo Roads o E pa si e Cla “u g ades , Engineering Journal, University of Khartoum, Vol.3 No.1, PP 51-57, Feb 2013. [43] )u a i M. M. E., A stud o Me ha i al “ta ilizatio to I p o e Ma gi al Base Mate ials i Kha tou , I te atio al Jou al of “ ie e and Research (IJSR), Vol. 3, ISSN 2319-7064 , June 2014.
62
Appendix
63
Appendix (A): Atterberg Limits Tests Data: 1. Soba soils- untreated. Liquid Limit Soba untreated soil Tin Number 1 2 3 4 5 Mass of wet soil + Tin (gm) 44.8 43.29 36.4 40.31 37.59 Mass of dry soil + Tin (gm) 36 35.08 29.88 32.85 30.65 Mass of Tin (gm) 14.94 15.12 14.5 15.1 14.48 Mass of wet soil (gm) 8.8 8.21 6.52 7.46 6.94 Mass of dry soil (gm) 21.06 19.96 15.38 17.75 16.17 Moisture Content (%) 41.7854 41.1323 42.3927 42.0282 42.919 Number of Blows 33 36 23 26 20
Tin No. Wt. of tin (gm) Wt. of wet soil + tin (gm) Wt. of dry soil + tin (gm) Moisture content m.c% Plastic limit Plasticity Index
7 18.80 30.09 28.15 20.749
64
8 20.05 29.76 28.21 18.995 19.885 22.
6 49.55 39.04 15.28 10.51 23.76 44.23 13
9 17.83 28.73 26.92 19.912
2. Medani Soil- Untreated: Liquid Limit Medani untreated soil Tin Number 16A 17A 18A 60B 32 59 Mass of wet soil + Tin (gm) 38.09 38.25 40.1 41.69 30.3 28.02 Mass of dry soil + Tin (gm) 25.09 24.99 26 29.85 21.69 20.77 Mass of Tin (gm) 5.3 5.37 5.24 12.8 9.4 10.61 Mass of wet soil (gm) 13 13.26 14.1 11.84 8.61 7.25 Mass of dry soil (gm) 19.79 19.62 20.76 17.05 12.29 10.16 Moisture Content (%) 65.6897 67.5841 67.9191 69.4428 70.057 71.3583 Number of Blows 42 32 26 20 18 12
Tin No. Wt. of tin (gm) Wt. of wet soil + tin (gm) Wt. of dry soil + tin (gm) Moisture content % Plastic limit PL Plasticity Index
25 19.33 25.63 24.04 33.7578
65
29 19.65 27.13 25.26 33.333 33.589 35
38 14.37 22.15 20.19 33.677
Moisture Content (%)
3. Medani soil treated with 3% lime + 0% Fly ash: Liquid Limit Medani: Soil+ 3% lime Tin Number 1 2 Mass of wet soil + Tin (gm) 37.82 39.26 Mass of dry soil + Tin (gm) 28.23 29.01 Mass of Tin (gm) 15 15.17 Mass of wet soil (gm) 9.59 10.25 Mass of dry soil (gm) 13.23 13.84 Moisture Content (%) 72.4868 74.0607 Number of Blows 30 26
3 40.73 29.57 14.52 11.16 15.05 74.1528 24
4 40.09 29.41 15.13 10.68 14.28 74.7899 22
Liquid Limit (LL) =74%
72 15
17
19
21
23
25
27
29
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
1 18.57 27.27 24.07 3.2 5.5 58.18182
66
2 17.01 22.45 20.68 1.77 3.67 48.22888 52.4 21.6
3 17.29 22.21 20.55 1.66 3.26 50.92025
31
Moisture Content (%)
4. Medani soil treated with 5% lime + 0% Fly ash: Liquid Limit Medani: Soil+ 5% lime Tin Number 5 6 Mass of wet soil + Tin (gm) 37.27 39.34 Mass of dry soil + Tin (gm) 28.33 29.78 Mass of Tin (gm) 14.54 15.28 Mass of wet soil (gm) 8.94 9.56 Mass of dry soil (gm) 13.79 14.5 Moisture Content (%) 64.8296 65.931 Number of Blows 27 23
7 41.28 30.86 15.26 10.42 15.6 66.7949 22
8 42.25 31.56 15.69 10.69 15.87 67.3598 20
Liquid Limit (LL) =65.5%
64 15
17
19
21
23
25
27
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
4 16.97 23.45 21.15 2.3 4.18 55.02392
67
5 17.54 24.33 22.09 2.24 4.55 49.23077 51.0 14.5
6 18.66 25.16 23.03 2.13 4.37 48.74142
29
5. Medani soil treated with 8% lime + 0% Fly ash: Liquid Limit Medani: Soil+ 8% lime 9
10
11
12
Mass of wet soil + Tin (gm)
42.65
41.36
42.26
40.74
Mass of dry soil + Tin (gm) Mass of Tin (gm) Mass of wet soil (gm) Mass of dry soil (gm) Moisture Content (%) Number of Blows
32.37 15.13 10.28 17.24 59.6288 29
31.52 15.27 9.84 16.25 60.5538 24
31.89 15.07 10.37 16.82 61.6528 22
30.86 15.13 9.88 15.73 62.8099 18
Moisture Content (%)
Tin Number
Liquid Limit (LL) =60.7% 59 15
17
19
21
23
25
27
29
31
Number of Blows
6. Medani soil treated with 12% lime + 0% Fly ash: Liquid Limit Medani: Soil+ 12% lime Tin Number
13
14
15
26
Mass of wet soil + Tin (gm)
43.21
35.91
43.92
44.72
Mass of dry soil + Tin (gm) Mass of Tin (gm) Mass of wet soil (gm) Mass of dry soil (gm) Moisture Content (%) Number of Blows
32.6 15.01 10.61 17.59 60.3184 30
25.55 8.44 10.36 17.11 60.5494 28
32.93 15.06 10.99 17.87 61.4997 24
33.5 15.36 11.22 18.14 61.8523 21
68
Moisture Content (%)
Liquid Limit (LL) =61.2% 60 15
17
19
21
23
25
27
29
31
Number of Blows
7. Medani soil treated with 15% lime + 0% Fly ash: Liquid Limit Medani: Soil+ 15% lime Tin Number 19 20 Mass of wet soil + Tin (gm) 37.63 43.61 Mass of dry soil + Tin (gm) 29.67 33.22 Mass of Tin (gm) 14.25 14.66 Mass of wet soil (gm) 7.96 10.39 Mass of dry soil (gm) 15.42 18.56 Moisture Content (%) 51.6213 55.9806 Number of Blows 30 26
21 41.65 32.12 15.32 9.53 16.8 56.7262 24
22 39.6 30.5 15.32 9.1 15.18 59.9473 21
Moisture Content (%)
60
55
Liquid Limit (LL) =56.3% 50 15
17
19
21
23
25
Number of Blows
69
27
29
31
8. Medani soil treated with 0% lime + 15% Fly ash: Liquid Limit Medani: Soil+ 0% Lime + 15% Fly ash Tin Number 5 6 4 Mass of wet soil + Tin (gm) 43.74 46.49 44.79 Mass of dry soil + Tin (gm) 32.37 34.24 33.02 Mass of Tin (gm) 14.53 15.29 15.12 Mass of wet soil (gm) 11.37 12.25 11.77 Mass of dry soil (gm) 17.84 18.95 17.9 Moisture Content (%) 63.7332 64.6438 65.7542 Number of Blows 31 27 23
7 43.46 32.24 15.45 11.22 16.79 66.8255 21
Moisture Content (%)
67
66
65
64
Liquid Limit (LL) =65.4%
63 20
22
24
26
28
30
32
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
7 18.55 24.81 22.97 1.84 4.42 41.62896
70
8 20.02 25.5 23.91 1.59 3.89 40.87404 41.2 24.2
9 17.78 24.04 22.22 1.82 4.44 40.99099
9. Medani soil treated with 0% lime + 20% Fly ash: Liquid Limit Medani: Soil+ 20% Fly ash Tin Number 12 23 Mass of wet soil + Tin (gm) 38.2 43.54 Mass of dry soil + Tin (gm) 29.37 32.72 Mass of Tin (gm) 15.14 15.74 Mass of wet soil (gm) 8.83 10.82 Mass of dry soil (gm) 14.23 16.98 Moisture Content (%) 62.052 63.722 Number of Blows 33 26
24 47.4 34.6 14.67 12.8 19.93 64.2248 24
25 45.53 33.53 15.09 12 18.44 65.0759 22
66
Moisture Content (%)
65 64 63
Liquid Limit (LL) =63.6%
62 61 20
22
24
26
28
30
32
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
Plastic Limit 10 18.23 23.72 22.08 1.64 3.85 42.5974
71
11 18.62 24.13 22.5 1.63 3.88 42.01031 42.3 21.3
12 18.93 23.54 22.17 1.37 3.24 42.28395
34
10. Medani soil treated with 0% lime + 25% Fly ash: Liquid Limit Medani: Soil+ 25% Fly ash Tin Number
4A
5A
8A
9A
Mass of wet soil + Tin (gm)
41.3
44.36
42.94
44.15
Mass of dry soil + Tin (gm) Mass of Tin (gm) Mass of wet soil (gm) Mass of dry soil (gm) Moisture Content (%)
31.38 15.15 9.92 16.23 61.1214
33.25 15.18 11.11 18.07 61.4831
32.32 15.3 10.62 17.02 62.3972
32.77 14.85 11.38 17.92 63.5045
29
27
24
19
Number of Blows
Moisture Content (%)
65
Liquid Limit (LL) =62.1%
64
63
62
61 18
20
22
24
26
28
30
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
13 19.22 23.93 22.51 1.42 3.29 43.16109
72
14 18.19 22.56 21.24 1.32 3.05 43.27869 43.2 18.9
15 18.54 23.67 22.12 1.55 3.58 43.29609
11. Medani soil treated with 0% lime + 30% Fly ash: Liquid Limit Medani: Soil+ 30% Fly ash Tin Number 6A 9 Mass of wet soil + Tin (gm) 45.25 46.27 Mass of dry soil + Tin (gm) 33.67 34.34 Mass of Tin (gm) 14.81 15.14 Mass of wet soil (gm) 11.58 11.93 Mass of dry soil (gm) 18.86 19.2 Moisture Content (%) 61.3998 62.1354 Number of Blows 30 27
10 44.22 33.03 15.29 11.19 17.74 63.0778 23
11 47.71 34.92 15.08 12.79 19.84 64.4657 17
Moisture Content (%)
65
Liquid Limit (LL) =62.6%
64
63
62
61 16
18
20
22
24
26
28
30
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
Plastic Limit 16 19.3 25.95 23.86 2.09 4.56 45.83333
73
17 18.96 25.98 23.79 2.19 4.83 45.34161 45.5 17.1
18 19.08 25.42 23.44 1.98 4.36 45.41284
32
12. Medani soil treated with 0% lime + 40% Fly ash: Liquid Limit Medani: Soil+ 40% Fly ash Tin Number 10A 11A Mass of wet soil + Tin (gm) 40.13 38.24 Mass of dry soil + Tin (gm) 30.13 28.77 Mass of Tin (gm) 15.2 15.04 Mass of wet soil (gm) 10 9.47 Mass of dry soil (gm) 14.93 13.73 Moisture Content (%) 66.9792 68.9731 Number of Blows 34 27
12A 43.99 32.1 15.08 11.89 17.02 69.859 22
16A 35.81 23.04 5.29 12.77 17.75 71.9437 16
73
Moisture Content (%)
72
Liquid Limit (LL) =69.4%
71 70 69 68 67 66 15
17
19
21
23
25
27
29
31
33
35
Number of Blows
Plastic Limit Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
54 17.23 22.33 20.78 1.55 3.55 43.66197
74
55 16.9 22.14 20.54 1.6 3.64 43.95604 43.8 25.6
56 17.42 23.33 21.53 1.8 4.11 43.79562
Moisture Content (%)
13. Medani soil treated with 3% lime + 5% Fly ash: Liquid Limit Medani: Soil+ 3% lime+ 5% Ash Tin Number 1 2 3 Mass of wet soil + Tin (gm) 51.49 49.03 50.47 Mass of dry soil + Tin (gm) 36.87 35.27 36.1 Mass of Tin (gm) 15.03 14.96 15.16 Mass of wet soil (gm) 14.62 13.76 14.37 Mass of dry soil (gm) 21.84 20.31 20.94 Moisture Content (%) 66.9414 67.7499 68.6246 Number of Blows 28 26 23
4 48.89 34.99 15.06 13.9 19.93 69.7441 20
Liquid Limit (LL) =68%
66 15
17
19
21
23
25
27
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
10A 15.23 20.44 18.85 1.59 3.62 43.92265
75
11A 15.11 19.9 18.48 1.42 3.37 42.1365 43.2 24.8
12A 15.17 20.42 18.83 1.59 3.66 43.44262
29
Moisture Content (%)
14. Medani soil treated with 5% lime + 5% Fly ash: Liquid Limit Medani: Soil+ 5% lime+ 5% Ash Tin Number 1 2 Mass of wet soil + Tin (gm) = 51.21 52.86 Mass of dry soil + Tin (gm)= 37.83 38.45 Mass of Tin (gm) = 15.72 14.51 Mass of wet soil (gm) = 13.38 14.41 Mass of dry soil (gm) = 22.11 23.94 Moisture Content (%) = 60.5156 60.1921 Number of Blows= 22 24
3 53.14 38.87 15.11 14.27 23.76 60.0589 27
4 48.34 35.77 14.69 12.57 21.08 59.63 30
Liquid Limit (LL) =60.2%
59 15
17
19
21
23
25
27
29
Number of Blows
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
19 14.89 21.42 19.39 2.03 4.5 45.11111
76
20 14.66 21.82 19.56 2.26 4.9 46.12245 45.9 14.3
21 15.32 21.24 19.36 1.88 4.04 46.53465
31
Moisture Content (%)
15. Medani soil treated with 8% lime + 5% Fly ash: Liquid Limit Medani: Soil+ 8% lime+ 5% Ash Tin Number 1 2 Mass of wet soil + Tin (gm) 52.68 50.64 Mass of dry soil + Tin (gm) 39.46 37.85 Mass of Tin (gm) 14.86 14.55 Mass of wet soil (gm) 13.22 12.79 Mass of dry soil (gm) 24.6 23.3 Moisture Content (%) 53.7398 54.8927 Number of Blows 29 26
3 54.11 40.23 15.28 13.88 24.95 55.6313 23
4 50.02 37.42 14.92 12.6 22.5 56 21
Liquid Limit (LL) =55%
53 15
17
19
21
23
25
27
29
31
Number of Blows
16. Medani soil treated with 12% lime + 5% Fly ash: Liquid Limit Medani: Soil+ 12% lime+ 5% Ash Tin Number 1 2 3 Mass of wet soil + Tin (gm) 47.48 52.73 52.82 Mass of dry soil + Tin (gm) 35.99 39.58 39.55 Mass of Tin (gm) 14.66 15.46 15.24 Mass of wet soil (gm) 11.49 13.15 13.27 Mass of dry soil (gm) 21.33 24.12 24.31 Moisture Content (%) 53.8678 54.5191 54.5866 Number of Blows 30 27 23
77
4 51.76 38.83 15.3 12.93 23.53 54.9511 21
Moisture Content (%)
Liquid Limit (LL) =55.5%
53 15
17
19
21
23
25
27
29
31
Number of Blows
17. Medani soil treated with 15% lime + 5% Fly ash: Liquid Limit Medani: Soil + 15% lime+ 5% Ash Tin Number
1
2
3
4
Mass of wet soil + Tin (gm)
56.02
53.77
49.87
47.24
Mass of dry soil + Tin (gm) Mass of Tin (gm) Mass of wet soil (gm) Mass of dry soil (gm) Moisture Content (%) Number of Blows
41.87 15.23 14.15 26.64 53.1156 29
40.26 15.15 13.51 25.11 53.8033 27
37.62 15.26 12.25 22.36 54.7853 24
35.49 14.49 11.75 21 55.9524 20
78
Moisture Content (%)
Liquid Limit (LL) =54.45%
53 15
17
19
21
23
25
27
29
31
Number of Blows
Moisture Content (%)
18. Medani soil treated with 3% lime + 10% Fly ash: Liquid Limit Medani: Soil+ 3% lime+ 10% Ash Tin Number 1 2 3 Mass of wet soil + Tin (gm) = 42.61 44.64 46.23 Mass of dry soil + Tin (gm)= 32.07 33.14 34.15 Mass of Tin (gm) = 15.28 14.96 15.17 Mass of wet soil (gm) = 10.54 11.5 12.08 Mass of dry soil (gm) = 16.79 18.18 18.98 Moisture Content (%) = 62.7755 63.2563 63.6459 Number of Blows= 29 26 24
4 42.78 31.75 14.51 11.03 17.24 63.9791 22
Liquid Limit (LL) =61.5% 62 15
17
19
21
23
25
Number of Blows 79
27
29
31
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
14A 14.95 19.64 18.06 1.58 3.11 50.80386
10A 15.22 22.52 20.11 2.41 4.89 49.28425 50.1 11.4
19. Gedarif untreated soil Liquid Limit Gedarif: Soil + 0% Lime + 0% Fly ash Tin Number 16A 17A 18A 60B Mass of wet soil + Tin (gm) 32.58 33.43 33.93 43.51 Mass of dry soil + Tin (gm) 21.16 21.38 21.47 29.98 Mass of Tin (gm) 5.28 5.38 5.23 12.85 Mass of wet soil (gm) 11.42 12.05 12.46 13.53 Mass of dry soil (gm) 15.88 16 16.24 17.13 Moisture Content (%) 71.9144 75.3125 76.7241 78.9842 Number of Blows 40 31 29 24
80
11A 15.1 21.47 19.34 2.13 4.24 50.23585
32 27.38 19.29 9.44 8.09 9.85 82.132 16
59 26.17 19.08 10.59 7.09 8.49 83.51 13
Tin No. Wt. of tin (gm) Wt. of wet soil + tin (gm) Wt. of dry soil + tin (gm) Moisture content m.c%
25 19.34 25.48 23.75 39.229
29 19.65 26.40 24.50 39.175 38.88 39.52
Plastic Limit Plasticity Index
38 14.36 19.53 18.10 38.235
20. Gedarif soil treated with 3% lime + 0% Fly ash: Liquid Limit Gedarif Soil + 3% lime + 0% Fly ash Tin Number
1
2
3
4
Mass of wet soil + Tin (gm)
45.87
44.91
48.35
49.43
Mass of dry soil + Tin (gm) Mass of Tin (gm) Mass of wet soil (gm) Mass of dry soil (gm) Moisture Content (%)
33.21 15.04 12.66 18.17 69.6753
32.34 14.53 12.57 17.81 70.5783
34.59 15.25 13.76 19.34 71.1479
35.08 15.12 14.35 19.96 71.8938
29
27
24
21
Moisture Content (%)
Number of Blows
Liquid Limit (LL) =70.9%
69 15
17
19
21
23
25
Number of Blows
81
27
29
31
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
1 14.98 21.16 19.12 2.04 4.14 49.27536
2 15.17 21.22 19.21 2.01 4.04 49.75248 49.2 21.7
10A 15.23 22.04 19.81 2.23 4.58 48.68996
Moisture Content (%)
21. Gedarif soil treated with 5% lime + 0% Fly ash: Liquid Limit Gedarif Soil + 5% lime 0% Fly ash Tin Number 1 2 3 Mass of wet soil + Tin (gm) 40.83 44.58 49.15 Mass of dry soil + Tin (gm) 30.18 32.53 35.19 Mass of Tin (gm) 14.74 15.15 15.28 Mass of wet soil (gm) 10.65 12.05 13.96 Mass of dry soil (gm) 15.44 17.38 19.91 Moisture Content (%) 68.9767 69.3326 70.1155 Number of Blows 28 26 23
4 47.56 33.73 14.11 13.83 19.62 70.4893 20
Liquid Limit (LL) =69.6%
68 15
17
19
21
23
Number of Blows
82
25
27
29
Plastic Limit Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
7 15.46 20.31 18.57 1.74 3.11 55.94855
8 15.23 20.66 18.71 1.95 3.48 56.03448
11A 15.12 20.96 18.86 2.1 3.74 56.14973 56.0 13.6
Moisture Content (%)
22. Gedarif soil treated with 3% lime + 5% Fly ash: Liquid Limit Gedarif: Soil+ 3% lime, 5% ash Tin Number 1 2 3 Mass of wet soil + Tin (gm) 36.47 35.85 37.15 Mass of dry soil + Tin (gm) 24.71 22.29 22.97 Mass of Tin (gm) 9.87 5.3 5.36 Mass of wet soil (gm) 11.76 13.56 14.18 Mass of dry soil (gm) 14.84 16.99 17.61 Moisture Content (%) 79.2453 79.8117 80.5224 Number of Blows 28 24 22
4 36.46 22.42 5.25 14.04 17.17 81.7705 20
Liquid Limit (LL) =79.9%
79 19
20
21
22
23
24
25
Number of Blows
83
26
27
28
29
Plastic Limit 1 7.98 12.04 10.66 1.38 2.68 51.49254
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
2 8.57 12.83 11.38 1.45 2.81 51.60142 51.5 28.4
3 9.44 13.27 11.97 1.3 2.53 51.3834
23. Gedarif soil treated with 3% lime + 10% Fly ash: Liquid Limit Gedarif Soil+ 3% lime + 5% ash Tin Number
1
2
3
4
Mass of wet soil + Tin (gm)
46.42
48.15
46.09
46.89
Mass of dry soil + Tin (gm) Mass of Tin (gm) Mass of wet soil (gm) Mass of dry soil (gm) Moisture Content (%)
32.22 12.91 14.2 19.31 73.537
33 12.64 15.15 20.36 74.4106
31.88 12.94 14.21 18.94 75.0264
32.09 12.65 14.8 19.44 76.1317
30
27
24
21
Moisture Content (%)
Number of Blows
Liquid Limit (LL) =74.9%
73 15
17
19
21
23
25
Number of Blows
84
27
29
31
Plastic Limit 1 13.04 19.87 17.58 2.29 4.54 50.44053
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
2 12.57 20.71 17.99 2.72 5.42 50.1845 50.3 24.6
3 3.8 10.47 8.24 2.23 4.44 50.22523
24. Gedarif soil treated with 0% lime + 15% Fly ash: Liquid Limit Gedarif: Soil + 0% Lime + 15% Fly ash Tin Number 13A 14A 15A Mass of wet soil + Tin (gm) 41.62 39.34 39.96 Mass of dry soil + Tin (gm) 30.5 28.73 29.02 Mass of Tin (gm) 15.22 14.93 15.01 Mass of wet soil (gm) 11.12 10.61 10.94 Mass of dry soil (gm) 15.28 13.8 14.01 Moisture Content (%) 72.7749 76.8841 78.0871 Number of Blows 33 26 22
25 41.18 29.69 15.11 11.49 14.58 78.8066 19
79
Moisture Content (%)
78 77 76 75 74
Liquid Limit (LL) =76.6%
73 72 18
20
22
24
26
28
Number of Blows
85
30
32
34
Plastic Limit 40 16.26 21.3 19.66 1.64 3.4 48.23529
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
41 16.03 20.47 19.03 1.44 3 48 45.4 31.2
42 16.18 21.09 19.69 1.4 3.51 39.88604
25. Gedarif soil treated with 0% lime + 20% Fly ash: Liquid Limit Gedarif: Soil 0% Lime + 20% Fly ash Tin Number 30 29 28 Mass of wet soil + Tin (gm) 34.88 33.61 36.72 Mass of dry soil + Tin (gm) 21.87 22.98 25.22 Mass of Tin (gm) 3.78 8.55 9.84 Mass of wet soil (gm) 13.01 10.63 11.5 Mass of dry soil (gm) 18.09 14.43 15.38 Moisture Content (%) 71.9182 73.666 74.7724 Number of Blows 29 26 23
27 35.5 23.57 7.98 11.93 15.59 76.5234 19
77
Moisture Content (%)
76 75 74 73
Liquid Limit (LL) =73.8% 72 71 18
20
22
24
Number of Blows
86
26
28
30
Plastic Limit 37 15.68 19.21 18 1.21 2.32 52.15517
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
39 15.79 19.51 18.23 1.28 2.44 52.45902 52.3 21.5
48 16.57 20.7 19.28 1.42 2.71 52.39852
26. Gedarif soil treated with 0% lime + 25% Fly ash: Liquid Limit Gedarif: Soil+ 0 % Lime 25% Fly ash Tin Number 8 14 31 Mass of wet soil + Tin (gm) 32.54 35.71 29.35 Mass of dry soil + Tin (gm) 22.46 24.2 18.56 Mass of Tin (gm) 8.46 8.44 3.91 Mass of wet soil (gm) 10.08 11.51 10.79 Mass of dry soil (gm) 14 15.76 14.65 Moisture Content (%) 72 73.033 73.6519 Number of Blows 32 28 26
590 31.91 21.77 8.3 10.14 13.47 75.2784 20
Moisture Content (%)
76
75
Liquid Limit (LL) =73.9%
74
73
72
71 18
20
22
24
26
28
Number of Blows
87
30
32
34
Plastic Limit 33 18.57 23.83 21.99 1.84 3.42 53.80117
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
34 18.38 23.8 21.91 1.89 3.53 53.54108 54.1 19.8
35 18.95 24.68 22.65 2.03 3.7 54.86486
27. Gedarif soil treated with 0% lime + 30% Fly ash: Liquid Limit Gedarif: Soil + 0% Lime + 30% Fly ash Tin Number 32 16A 17A Mass of wet soil + Tin (gm) 38.38 36.93 28.62 Mass of dry soil + Tin (gm) 26.19 23.56 18.69 Mass of Tin (gm) 9.42 5.28 5.31 Mass of wet soil (gm) 12.19 13.37 9.93 Mass of dry soil (gm) 16.77 18.28 13.38 Moisture Content (%) 72.6893 73.14 74.2152 Number of Blows 28 24 22
18A 34.06 21.06 5.22 13 15.84 82.0707 15
83 82
Moisture Content (%)
81
Liquid Limit (LL) =73.5%
80 79 78 77 76 75 74 73 72 14
16
18
20
22
24
Number of Blows
88
26
28
30
Plastic Limit 49 17.23 22.08 20.39 1.69 3.16 53.48101
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
55 16.89 20.44 19.21 1.23 2.32 53.01724 53.2 20.3
57 19.58 23.24 21.97 1.27 2.39 53.13808
28. Gedarif soil treated with 0% lime + 40% Fly ash: Liquid Limit Gedarif: Soil + 0% Lime + 40% Fly ash Tin Number 13A 14A 15A Mass of wet soil + Tin (gm) 42.58 41.1 39.19 Mass of dry soil + Tin (gm) 30.5 29.4 28.33 Mass of Tin (gm) 15.14 14.86 14.95 Mass of wet soil (gm) 12.08 11.7 10.86 Mass of dry soil (gm) 15.36 14.54 13.38 Moisture Content (%) 78.6458 80.4677 81.1659 Number of Blows 36 29 26
17A 37.31 22.87 5.32 14.44 17.55 82.2792 21
Moisture Content (%)
83
82
Liquid Limit (LL) =81.4%
81
80
79
78 20
22
24
26
28
30
Number of Blows
89
32
34
36
38
Plastic Limit 39 15.84 20.73 19.01 1.72 3.17 54.25868
Tin No Mass of Tin Mass of wet soil + tin Mass of dry soil + tin Mass of water Mass of dry soil Moisture content Plastic Limit Plasticity Index
40 16.32 20.94 19.32 1.62 3 54 53.7 27.7
41 16.07 21.42 19.57 1.85 3.5 52.85714
Appendix (B): Grain size analysis Tests Data: 1. Medani Soil (Untreated) 100 90 80 70 60 50
30 20 10
0.01
0.1
SILT FINE
MEDIU COUR SE M
1
10
SAND FINE
MEDIU COURS M E
90
GRAVEL FINE
MEDIU COURS M E
100
COBBlES
0 0.001
CLAY
%PASSING
40
2. Gedarif Soil (Untreated) 100 90 80 70 60
40 30 20 10
0.01
0.1
SILT FINE
MEDIU COURS M E
1
10
SAND FINE
MEDIU COURS M E
91
GRAVEL FINE
MEDIU COURS M E
100
COBBlES
0 0.001
CLAY
%PASSING
50
Appendix (C): Compaction Tests Data: 1. Medani Soil (Untreated) 1.60
O.M.C. =23.8% Max. Dry Density = 1.486 gm/cm3
Dry Density( gm/cm3)
1.55
1.50
1.45
1.40
1.35 10.00
15.00
20.00
25.00
30.00
35.00
Moisture Content % 2. Medani soil treated with 8% lime:
Dry Density( gm/cm3)
1.50
1.45
O.M.C. =24% Max. Dry Density = 1.48gm/cm3 1.40 13.00
15.00
17.00
19.00
21.00
23.00
Moisture Content %
92
25.00
27.00
29.00
3. Medani soil treated with 8% lime + 5% Fly ash: 1.440
Dry Density( gm/cm3)
1.420 1.400 1.380 1.360 1.340
1.320
O.M.C. =30.5% Max. Dry Density = 1.416 gm/cm3
1.300 1.280 1.260 20.21
23.22
27.52 29.99 Moisture Content %
33.24
35.73
4. Medani soil treated with 5% lime + 10% Fly ash: 1.45
Dry Density( gm/cm3)
O.M.C. =30.1% Max. Dry Density = 1.41 gm/cm3 1.40
1.35
1.30 15.00
20.00
25.00
30.00
Moisture Content %
93
35.00
40.00
5. Gedarif soil (Untreated) 1.420
Dry Density( gm/cm3)
1.400 1.380 1.360 1.340 O.M.C. =26% Max. Dry Density = 1.40gm/cm3
1.320 1.300 1.280 10.59
20.18
24.09 Moisture Content %
29.97
35.76
6. Gedarif soil treated with 8% lime: 1.45
Dry Density( gm/cm3)
1.40
1.35
1.30
O.M.C. =29.5% Max. Dry Density = 1.40gm/cm3
1.25
1.20 15.00
20.00
25.00
30.00
Moisture Content %
94
35.00
40.00
7. Gedarif soil treated with 5% lime + 5% Fly ash: 1.440 1.420
Dry Density( gm/cm3)
1.400 1.380 1.360 1.340 1.320 1.300
O.M.C. =27.2% Max. Dry Density = 1.418gm/cm3
1.280 1.260 1.240 1.220 17.50
24.15
26.62
29.18
31.43
Moisture Content %
8. Gedarif soil treated with 5% lime + 10% Fly ash: 1.400
Dry Density( gm/cm3)
1.380
1.360
1.340
1.320
O.M.C. =29.5% Max. Dry Density = 1.385gm/cm3
1.300
1.280 18.58
23.17
26.70
29.17
Moisture Content %
95
31.49
33.52
Appendix (D): Soaked and Unsoaked CBR Tests Data: 1. Medani Soil (untreated) (Soaked CBR) 70 60
Pressure (Ib/in²)
50 40 30 20 10 0 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Pentration ( inch)
Pressure (Ib/in²)
2. Medani soil treated with 8% lime (Unsoaked CBR): 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0
0.1
0.2 Pentration ( inch) 96
0.3
Pressure (Ib/in²)
3. Medani soil treated with 8% lime (Soaked CBR): 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 0
0.1
0.2
Pentration ( inch) 4. Medani soil treated with 8% lime + 5% Fly ash (Unsoaked CBR): 550 500 450
Pressure (Ib/in²)
400 350
300 250 200 150 100 50 0
0
0.1
0.2 Pentration ( inch)
97
0.3
0.4
5. Medani soil treated with 8% lime + 5% Fly ash (Soaked CBR): 1400 1200
Pressure (Ib/in²)
1000 800 600 400 200 0 0
0.1
Pentration ( inch)
0.2
0.3
6 Medani soil treated with 5% lime + 10% Fly ash (Unsoaked CBR): 400 350
Pressure (Ib/in²)
300 250 200 150 100
50 0 0
0.1 Pentration ( inch)
98
0.2
0.3
7. Medani soil treated with 5% lime + 10% Fly ash (Soaked CBR): 900 800
Pressure (Ib/in²)
700 600 500 400 300 200 100 0 0
0.1
0.2
Pentration ( inch)
8. Gedarif Soil (Untreated) (Soaked CBR): 60
Pressure (Ib/in²)
50
40
30
20
10
0 0
0.1
0.2
0.3
0.4
Pentration ( inch) 99
0.5
0.6
0.7
0.8
Pressure (Ib/in²)
9. Gedarif soil treated with 8% lime (Unsoaked CBR): 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0
0.1
0.2
Pentration ( inch) 10. Gedarif soil treated with 8% lime (Soaked CBR): 1200 1100 1000
Pressure (Ib/in²)
900 800 700 600 500 400 300 200 100 0
0
0.1 Pentration ( inch) 100
0.2
Pressure (Ib/in²)
11. Gedarif soil treated with 5% lime + 5% Fly ash (Unsoaked CBR): 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0
0.1
0.2
0.3
Pentration ( inch) 12. Gedarif soil treated with 5% lime + 5% Fly ash (Soaked CBR): 1100 1000 900
Pressure (Ib/in²)
800 700 600 500 400 300 200 100 0 0
0.1 Pentration ( inch) 101
0.2
13. Gedarif soil treated with 5% lime + 10% Fly ash (Unsoaked CBR): 550 500 450
Pressure (Ib/in²)
400 350 300 250 200 150 100 50 0 0
0.1 Pentration ( inch)
0.2
0.3
Pressure (Ib/in²)
14 Gedarif soil treated with 5% lime + 10% Fly ash (Soaked CBR): 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0
0.1 Pentration ( inch) 102
0.2
Appendix (E): Unconfined Compression Strength Tests Data: Sample diameter = 1.5 in. Sample height = 3 in. Deformation div. = 0.001 in. Stress div. = 8.4 N. 1. Medani soil (untreated) Unconfined Stress (Div) Deformation (Div) 0 0 10 11 20 25 30 38 40 50 50 61 60 68 70 74 80 78 90 81 100 82 110 84 120 85 130 86 140 86 150 86 160 87 170 87.5 180 87.5 190 87
2. Medani soil treated with 8% lime Unconfined Stress (Div) Deformation (Div) 0 0 10 23 20 59 30 94 40 122 50 136 60 143 70 139 80 126
103
3. Medani soil treated with 8% lime+5% fly ash
Unconfined Deformation (Div) 0 10 20 30 40 50 60 70 80
4. Medani soil treated with 5% lime+10% fly ash
Unconfined Deformation (Div) 0 10 20 30 40 50 60 70 80
Stress (Div) 0 25 83 137 150 130
5. Gedarif soil (untreated) Unconfined Stress (Div) Deformation (Div) 0 0 10 15 20 30 30 42 40 51 50 54 60 54 70 53 80 52 90 50.5 100 49
Stress (Div) 0 43 97 138 158 159 154 143
6. Gedarif soil treated with+8% lime. Unconfined Stress (Div) Deformation (Div) 0 0 10 30 20 104 30 175 40 230 50 254 60 210 70 165
104
7. Gedarif soil treated with 5% lime + 5% fly ash.
Unconfined Deformation (Div) 0 10 20 30 40 50 60 70 80 90 100
8. Gedarif soil treated with 5% lime + 10% fly ash.
Unconfined Deformation (Div) 0 10 20 30 40 50 60 70 80
Stress (Div) 0 24 56 92 130 164 190 204 210 201 178
105
Stress (Div) 0 38 78 112 135 148 159 160 145
Appendix (F): Swell Pressure Tests Data: 1. Medani soil (untreated) Load (Ib) 0 7.5 15 22.5
Reading (div) 1200 1311 1249 1165
Volume of ring (cm3) Ring + wet soil before test (gm) Ring + wet soil after test (gm) Ring + dry soil (gm) Ring empty (gm) Water in soil before test (gm) Water in soil after test (gm) Moisture content before test (%) Moisture content after test (%) Total density (gm/cm3) Dry density (gm/cm3)
86.83 244.41 251.28 214.32 84.64 30.09 36.96 23.2033 28.5009 1.84003 1.49349
1400
1300
1200
1100
1000
900 8
14
20 106
22
24
2. Gedarif soil (untreated) Load (Ib) 0 7.5 15 30
Reading (div) 1200 1373 1348 1174
Volume of ring (cm3) Ring + wet soil before test (gm) Ring + wet soil after test (gm) Ring + dry soil (gm) Ring empty (gm) Water in soil before test (gm) Water in soil after test (gm) Moisture content before test (%) Moisture content after test (%) Total density (gm/cm3) Dry density (gm/cm3)
86.83 232.64 238.95 201.98 79.34 30.66 36.97 25 30.1451 1.76552 1.41242
1400
1300
1200
1100
1000
900 8
14
20
107
22
24
26
28
30
