Solid waste is the most common which consists of Municipal ... materials, who knew before that when you convert wood to paper, you can also convert the ... Sugarcane bagasse is not an exception when it comes to converting waste back to .... have a strong enough bond with the hardened cement paste and do not put the ...
Engineering Properties of Sugarcane Bagasse as Supplementary Cementitious Material in Plain Concrete
CHAPTER ONE INTRODUCTION 1.1 Background of Study Waste is a problem that Engineers worldwide have been trying to solve, when not improperly disposed of it could lead to havoc such as flooding, diseases etc. But when these wastes are properly taken care of, it could be converted to resources and could just help reduce the use of our natural resources such as water, metal etc. Organisations worldwide have been trying to control wastes by converting wastes back to usable materials, there are different kinds of wastes i.e. Solid Waste, Waste Water etc. Solid waste is the most common which consists of Municipal wastes, Industrial Wastes and Hazardous Wastes. Municipal Wastes are gotten from residential and commercial zone which can be further classified into Food wastes (i.e. animal, fruit, vegetable residues etc.), Rubbish (i.e. paper, cardboard, plastics, textiles, leather, furniture etc.), Ashes and residues, Demolition and Construction Materials, Special Wastes (i.e. dead animals, abandoned vehicles etc.) and Semi Solid Wastes (Owamah., 2016). Using a case study of Nigeria with an estimated population of 162, 470, 737 with an estimated waste generation of 0.65kg/person /day, and about 50% of waste generated nationwide being Agro wastes. Agro wastes are one of the most common waste material that can also be converted into usable materials, who knew before that when you convert wood to paper, you can also convert the paper back to wood. But thanks to research made we can now convert our wastes back to
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materials. Agro wastes that can be converted back to usable materials include but are not limited to Sugarcane bagasse, rice husk, maize waste, sawdust, animal blood, animal wastes. Sugarcane waste is a major waste in Nigeria and also other countries such as India, South Africa etc. it has been discovered that sugarcane waste can be converted to building materials such as particle board and as a supplementary cementitious material in concrete. But in this paper, I would be discussing how we can use it as a supplementary cementitious material in concrete. Wastes gotten from sugarcane i.e. after extracting the sugar juice is called Sugarcane Bagasse. Sugar cane is the common name of a species of herb belonging to the grass family. It belongs to the family Gramineae. The botanical classification is Saccharum officinarum, and it is a perennial plant which can grow up to 4.25 m. The names sugar and sugar cane have been derived from the Sanskrit word, Sharkara. Sugarcane is indigenous to Brazil and India. In Nigeria, it is mostly grown in the northern part (i.e. Sokoto, Taraba, Niger etc.) of the country and transported to the southern part for processing into sugar cane juice, but it is mostly processed into sugar by extracting the liquid from it leaving the sugar cane bagasse. Sugar cane is a tropical crop requiring a hot climate. However, it also grows well in a subtropical climate. It has wider adaptability and grows well where the temperature ranges between 20 and 35 °C. It responds well to a long period of sunlight (12 to 14 hours). High humidity (80–85 %) favors rapid cane elongation during the main growth period. It requires a rainfall of between 1,100 and 1,500 mm, abundant in the months of vegetative growth followed by a dry period for ripening. Humic soils from 100 to 150 cm depth with good drainage are most suitable. It grows well in deep, well-drained soils of medium fertility of sandy loam soil textures with a pH range between 6,0 to 7,7 (Thabo., 2012). Utilization of sugar cane bagasse as cement replacement materials would help reduce the cost of concrete production and also minimize the negative environmental effects of the disposal of these wastes. The Sugarcane bagasse ash (SCBA) is obtained as a by-product of control burning of sugarcane bagasse. SCBA constitutes an 2
environmental nuisance as they form refuse heaps in areas they are disposed of. It is cultivated in about seventy-four countries between 400N and 32.50S, approximately encompassing half of the globe (Agboire et al., 2002). In the past, SCB was burnt as a means of solid waste disposal. But with the increasing cost of the natural gas, electricity, and fuel, and with the calorific properties of these wastes, bagasse has been used as the principal fuel in cogeneration plants to produce electric power (Aigbodion et al., 2010). Search for alternative binders or cement replacement materials has become a challenge for national development and forward planning. Since last few years, tremendous efforts have been made to increase the use of materials to partially replacement cement in concrete works. According to Swamy (1986), supplementation of cement production with natural pozzolans has proved attractive in developing countries. In recent years, there have been projects to develop known deposits in Indonesia, Tanzania, Trinidad, Dominica and other countries.
1.2 Aim and Objective The aim of this research is to investigate the engineering properties of sugarcane bagasse ash as a supplementary cementitious material in plain concrete. The objectives are;
To investigate the effect of modification Portland cement with sugarcane bagasse ash.
To determine the engineering properties of concrete when sugarcane bagasse is used as a supplementary cementitious material.
To
1.3 Justification To a layman, waste is a commodity that should be disposed of destroyed, but as an engineer when we see waste, we think of possible uses of the waste to building materials and materials
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as a whole. Sugarcane bagasse is not an exception when it comes to converting waste back to usable materials when an engineer sees sugarcane bagasse, he should see the use for Particleboards and as an additive in concrete. Sugarcane bagasse is a very common waste in Nigeria which is mostly disposed by burning and landfill, but by research from this paper it would state that the bagasse can be transferred to an additive to be used in concrete and not just as an additive, it would also help reduce the amount of cement needed in a concrete mixture. And this would be a very necessary material right now in Nigeria especially with the increase in price of cement in the country now, and also from research it was found out that the addition of SCBA to concrete adds more durability to the concrete thereby allowing the concrete to be to resist weathering action, chemical attack, and abrasion.
1.4 Scope of Work This research paper looks into the utilization of sugarcane bagasse ash as an additive when mixing concrete and concrete blocks. For this purpose, a concrete block would be produced from this research using sugarcane bagasse ash and another without sugarcane bagasse ash and their physical and mechanical properties would be tested to determine which one would be more sustainable for building construction.
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CHAPTER TWO LITERATURE REVIEW 2.1 Overview In concrete, the binder is typically ordinary Portland cement (OPC), which provides essential strength and durability. However, the manufacturing process used in cement production results in the depletion of some natural resources, consumption of excess energy and also leads to the emission of carbon dioxide to the atmosphere (Elisabeth Arif et al., 2016). It is therefore very important to effectively utilize alternative supplementary cementitious materials in concrete. Sugarcane bagasse is used as fuel in the cogeneration process to produce steam and electricity in sugar industries and when bagasse is burnt in combustion boiler under controlled burning, reactive amorphous silica is formed in the residual ashes (A. Bahurudeen et al., 2014). The ash, therefore, becomes an industrial waste and poses disposal problems. Studies have been carried out on the utilization of bagasse ash obtained directly from the industries to study pozzolanic activity and their suitability as binders by partially replacing cement (Prashant O. Modani, M.R. Vyawahare, 2013). The reactivity of sugarcane bagasse ash is directly dependent on the conditions when burning the bagasse. Maximum reactivity can be achieved by burning bagasse at around 5000c. Sugarcane bagasse is burned in plants at temperatures between 7000C and 9000C, depending on its moisture content. Thus, pozzolans in bagasse ash are not obtained by the uncontrolled burning of bagasse in plants (F.C.R. Almeida et al., 2015). Cordeiro (2008) et al., analysed the influence of the particle size of the bagasse ash on the compressive strength and density and found out that the reduction in the particle size of the bagasse ash resulted in an improvement in the pozzolanic activity. It has also been reported an increase in the compressive strength of concrete with the addition of bagasse ash and it has also been demonstrated that the optimal percentage of cement replacement is 20%. Ganesan (2007) 5
et al., also found out that the replacement of 20% of cement with bagasse ash decreased permeability and increased durability. Meanwhile, Hernandez (2012) et al., found that the higher the content of the bagasse ash, the higher the content of chlorides in surface layers of mortar specimens, which led them to conclude that the addition of 10% and 20% of bagasse ash reduced the diffusion coefficient by about 50%. The results obtained by different researchers show that when post-treated, bagasse ash have significant pozzolanic activity and can be used as additives in concrete because they help to improve mechanical and durability properties. Unfortunately, all the methods used to activate bagasse ash demand a lot of energy, making it necessary to investigate whether or not the impairment of the properties of mortars or concretes caused by the use of untreated ashes is tolerable.
2.2 Concrete This is a composite material that consists essentially of a binding medium, a mixture of Portland cement and water, within which are embedded particles or fragments of aggregate, usually a combination of fine and coarse aggregate. Concrete is by far the most versatile and most widely used construction material worldwide. It can be engineered to satisfy a wide range of performance specifications, unlike other building materials, such as natural stone or steel, which generally have to be used as they are. Concrete’s versatility, durability, sustainability, and economy have made it the world’s most widely used construction material (McGraw, 2003). According to Yunusa (2011) every concrete has its strength in N/mm2 when subject to test after 28 days of curing in any medium. The choice of concrete grade, depends on the purpose and usage as follows:
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Table 2.1: Concrete Grades
Concrete Grade
Usage
Ratio Cement,
N/mm2
Sand and
10 15 20
Aggregates 1:4:8 1:3:6 1:2.5:5
25
1:2:4
30
1:1.5:3
Heavy Reinforced concrete/pre-cast
35
1:1.5:2
40
1:1:1
Prestressed/pre=cast concrete Very heavy reinforced concrete/precast/prestressed
Blinding concrete Mass concrete Light reinforced concrete Reinforced concrete/precast
(Yunusa, 2011)
2.2.1 Constituents of Concrete
Cement
Aggregates
Water
Additives
Admixtures
2.2.1.1 Cement There are many different kinds of cement. In concrete, the most commonly used is Portland cement, a hydraulic cement which sets and hardens by chemical reaction with water and is capable of doing so under water. Cement is the “glue” that binds the concrete ingredients together and is instrumental for the strength of the composite (Teyckenne et al., 1997).
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There are two types
Pozzolanic Cements
Hydraulic Cements
Pozzolanic Cement: any siliceous material that develops hydraulic cementitious properties when interacted with hydrated lime. Hydraulic Cement: Cement is considered hydraulic because of their ability to set and harden under or with excess water through the hydration of the cement's chemical compounds or minerals. Some types of hydraulic cement include;
Hydraulic lime: Only used in specialized mortars. Made from calcination of clay-rich limestones.
Natural cement: Misleadingly called Roman. It is made from argillaceous limestones or interbedded limestone and clay or shale, with few raw materials. Because they were found to be inferior to portland, most plants switched.
Portland cement: Artificial cement. Made by the mixing clinker with gypsum in a 95:5 ratio.
Portland-limestone cement: Large amounts (6% to 35%) of ground limestone have been added as a filler to a portland cement base.
Blended cement: Mix of portland cement with one or more SCM (supplementary cementitious materials) like pozzolanic additives.
Pozzolan-lime cement: Original Roman cement. Only a small quantity is manufactured in the United States. A mix of pozzolans with lime.
Masonry cement: Portland cement where other materials have been added primarily to impart plasticity.
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Aluminous cement: Limestones and bauxite are the main raw materials. Used for refractory applications (such as cementing furnace bricks) and certain applications where rapid hardening is required. It is more expensive than portland. There is only one producing facility in the U.S.
Composition of Cement: In all the Portland Cements, there are four major compounds. The variation in percentage composition of compounds influences the properties of cement. Types of Cement using IS codes and physical properties: Table 2.2: Types of cement Sr. No.
1
2
3
4
5
6
Type of Cement
33 grade OPC (IS 269– 1989) 43 grade OPC (IS 8112– 1989) 53 grade OPC (IS 12269– 1987) Sulphate Resisting Cement. SRC (IS 12330– 1988) Portland Pozzolana Cement. PPC (IS 1489– 1991) Part-I Rapid Hardening Cement. PPC (IS 8041– 1990)
Fineness (m2 / Kg) Min
Soundness
Setting Time (minutes) Initial Final (min) (max)
Autoclave (max) (%)
225
Le- Chat (max) (mm) 10
0.8
30
225
10
0.8
225
10
225
Compressive Strength (MPa) 1D (min)
3D (min)
7D (min)
28 D (min)
600
NS
16
22
33
30
600
NS
23
33
Min-43 Max-58
0.8
30
600
NS
27
37
53
10
0.8
30
600
NS
10
16
33
300
10
0.8
30
600
NS
16
22
33
325
10
0.8
30
600
16
27
NS
NS
9
7
8
9
10
11
12
Portland Slag Cement. PSC (IS 455– 1989) Super Sulphated Cement. (IS 6909–1990) Low Heat Cement. (IS 12600– 1989) Masonry Cement. (IS 3466–1988) 43-S grade OPC (IS 8112– 1989) 53-S grade OPC (IS 12269– 1987)
225
10
0.8
30
600
NS
16
22
33
400
5
NS
30
600
NS
15
22
30
320
10
0.8
60
600
NS
10
16
35
*
10
1.0
90
1440
NS
NS
2.5
5.0
370
10
0.8
60
600
NS
NS
37.5
NS
370
10
0.8
60
600
NS
NS
37.5
NS
(Yunusa, 2011) 2.2.1.2 Aggregates Gravel, stone, and sands form the granular structure, which must have its voids filled as completely as possible by the binder glue. They make up approximately 80 % of the weight and 70–75% of the volume. Optimum use of the aggregate size and quality improves the concrete quality (T. Hirschi et al., 2005). Aggregates can occur naturally (fluvial or glacial); for high-quality concrete they are cleaned and graded in industrial facilities by mechanical processes such as mixing together, crushing, screening and washing (mechanical preparation). Suitable as concrete aggregates are materials which do not interfere with the cement hardening, have a strong enough bond with the hardened cement paste and do not put the resistance of the concrete at risk.
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Table 2.3: Aggregates
Aggregates
Density
Sources
Standard Aggregates
Density 2.2–3 kg/dm³
Heavyweight Aggregates
Density > 3.0 kg/dm³
Lightweight Aggregates
Density < 2.0 kg/dm³
Hard Aggregates
Density > 2.0 kg/dm³
Recycled Granulates
Density approx. 2.4 kg/dm³
From natural deposits, e.g. river gravel, moraine gravel etc. Material rounded or crushed (e.g. excavated tunnel) Such as barytes, iron ore, steel granulates. For the production of heavy concrete (e.g. radiation shielding concrete) Such as expanded clay, pumice, polystyrene. For lightweight concrete, insulating concretes Such as quartz, carborundum; e.g. for the production of granolithic concrete surfacing From crushed old concrete. (Yunusa, 2011)
Important Terms in Aggregate
Natural aggregate:
Comes from mineral deposits; it only undergoes mechanical preparation and/or washing.
Aggregate mix:
Aggregate consisting of a mixture of coarse and fine aggregates (sand). An aggregate mix can be produced without prior separation into coarse and fine aggregates or by combining coarse and fine aggregates (sand).
Recycled aggregate:
Aggregate made from mechanically processed inorganic material previously used as a building material (i.e. concrete). 11
Filler (rock flour):
Aggregate predominantly passing the 0.063 mm sieve, which is added to obtain specific properties.
Particle size group:
Designation of an aggregate by lower (d) and upper (D) sieve size, expressed as d/D.
Fine aggregate (sand):
Designation for smaller size fractions with D not greater than 4 mm. Fine aggregates can be produced by the natural breakdown of rock or gravel and/or crushing of rock or gravel, or by the processing of industrially produced minerals.
Coarse aggregate:
Designation for larger size fractions with D not less than 4 mm and d not less than 2 mm.
Naturally formed aggregate 0/8 mm:
Designation for a natural aggregate of glacial or fluvial origin with D not greater than 8 mm (can also be produced by mixing processed aggregates).
Fines:
A proportion of an aggregate passing the 0.063 sieve.
Granulometric composition:
Particle size distribution expressed as the passing fraction in percent by weight through a defined number of sieves.
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2.2.1.3 Water T. Hirschi et al., (2005) said that the suitability of water for concrete production depends on its origin. The water must first be analysed for traces of oil and grease, foaming (detergents), suspended substances, odor (e.g. no odor of hydrogen sulphide after adding hydrochloric acid), acid content (pH _ 4) and humic substances. The following constitutes usable and unusable water in concrete;
Drinking water:
Suitable for concrete. Does not need to be tested.
Water recovered from processes in the concrete industry (e.g. wash water):
Generally suitable for concrete but the requirements in annex A of the standard must be met (e.g. that the additional weight of solids in the concrete occurring when water recovered from processes in the concrete industry is used must be less than 1% of the total weight of the aggregate contained in the mix).
Ground water:
May be suitable for concrete but must be checked.
Natural surface water and industrial process water:
May be suitable for concrete but must be checked.
Sea water or brackish water:
May be used for non-reinforced concrete but is not suitable for reinforced or pre-stressed concrete. The maximum permitted chloride content in the concrete must be observed for concrete with steel reinforcement or embedded metal parts.
Wastewater: 13
Not suitable for concrete. 2.2.1.4 Additives Concrete additives are fine materials which are generally added to concrete in significant proportions (around 5–20 %). They are used to improve or obtain specific fresh and/or hardened concrete properties. There are two types of inorganic concrete additive: Type I Virtually inactive materials such as lime fillers, quartz dust, and colour pigments.
Pigments
Pigmented metal oxides (mainly iron oxides) are used to colour concrete. They are added at levels of 0.5–5 % of the cement weight; they must remain colour-fast and stable in the alkaline cement environment. With some types of pigment, the water requirement of the mix can increase.
Rock flours (quartz dust, powdered limestone)
Low fines mixes can be improved by adding rock flours. These inert materials are used to improve the grading curve. The water requirement is higher, particularly with powdered limestone. Type II Pozzolanic or latent hydraulic materials such as natural pozzolans (trass), fly ash, bagasse ash, and silica dust. Fly ash is a fine ash from coal-fired power stations which is used as an additive for both cement and concrete. Its composition depends mainly on the type of coal and its origin and the burning conditions. Silica dust (Silica fume) consists of mainly spherical particles of amorphous silicon dioxide from the production of silicon and silicon alloys. It has a specific
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surface of 18–25 m² per gram and is a highly reactive pozzolan. Standard dosages of silica dust are 5% to 10 % max. of the cement weight. 2.2.1.5 Admixtures While aggregate, cement, and water are the main ingredients of concrete, there are a large number of minerals and chemicals that may be added to the concrete. Concrete admixtures are liquids or powders which are added to the concrete during mixing in small quantities, normally based on the cement content. They influence the properties of the fresh and/or hardened concrete chemically and/or physically. Admixtures being used in concrete includes but are not limited to the following:
Admixtures (Definitions and Effects)
Water reducer: Enables the water content of a given concrete mix to be reduced without affecting the consistency, or increases the workability without changing the water content, or achieves both effects.
Superplasticizer: Enables the water content of a given concrete mix to be greatly reduced without affecting the consistency, or greatly increases the workability without changing the water content, or achieves both effects.
Stabilizer: Reduces mixing water bleeding in the fresh concrete.
Air entrainer: Introduces a specific quantity of small, evenly distributed air voids during the mixing process which remains in the concrete after it hardens.
Set accelerator: Reduces the time to initial set, with an increase in initial strength.
Hardening accelerator: Accelerates the initial strength with or without an effect on the setting time.
Retarder: Retards the time to initial set and prolongs the consistency.
Water proofer: Reduces the capillary water absorption of the hardened concrete. 15
Retarder/water reducer: It has the combined effects of a water reducer (main effect) and a retarder (additional effect).
Retarder/superplasticizer: It has the combined effects of a superplasticizer (main effect) and a retarder (additional effect).
Set accelerator/water reducer: It has the combined effects of a water reducer (main effect) and a set accelerator (additional effect).
2.2.2 Properties of Concrete
Workability
Durability
Strength
Volume change
Air entrainment
Density
2.2.2.1 Workability Workability is one of the most important of these properties. The degree of workability necessary in a concrete mix depends entirely upon the purpose for which it is used and the methods and equipment used in handling and placing it in the work. The factors that affect the workability of concrete are size distribution of the aggregate, shape of the aggregate particles, gradation and relative proportions of the fine and coarse aggregate, plasticity, cohesiveness, and consistency of the mix (Teyckenne et al., 1997). 2.2.2.2 Durability The ultimate durability is the most important property of concrete. To ensure a high degree of durability, it is essential that clean, sound materials and the lowest possible water content are used in the concrete, together with thorough mixing. Good consolidation during placement of 16
the concrete is important, as are proper curing and protection of the concrete during the early hardening period, which assures favorable conditions of temperature and moisture. Cure concrete properly for a minimum of three days in order to develop good durability. Another property that helps ensure durability is the water to cementitious ratio (Teyckenne et al., 1997). 2.2.2.3 Strength The strength of concrete is the next important property to consider. With a fixed amount of cement in a unit volume of concrete, the strongest and most impermeable concrete is one that has the greatest density, i.e., which in a given unit volume has the largest percentage of solid materials. The use of the absolute minimum quantity of water required for proper placement ensures the greatest strength of the concrete. It is essential that freshly mixed concrete be thoroughly consolidated to eliminate air pockets and secure maximum density in the structure. The Engineer must prevent the occurrence of loosely textured or porous concrete matrix called "honeycombing" to achieve maximum strength and density (Teyckenne et al., 1997). 2.2.2.4 Volume change Concrete continually undergoes changes in its volume from one cause or another throughout its service life. These constant changes are the principal causes of the ultimate failure or deterioration of the concrete. Plastic shrinkage is the first change to occur. Plastic shrinkage is caused by volume loss due to the hydration reaction and by evaporation. This volume change is controlled to some extent in the original mix design by using low sand and low water contents. After the concrete has changed from the plastic to the hardened state, it is subject to changes in its volume and dimensions due to changes in temperature as well as the creep. Creep is deformation under sustained loading. Expansion or contraction of the concrete due to temperature change may produce irregular cracking in the structure. Hardened concrete is also subject to volume change due to changes in its moisture content. All concrete is porous and absorbent and will take up or lose moisture if given the opportunity. This action tends to induce 17
internal stresses in the concrete structure if the change in volume is restrained to any degree (Teyckenne et al., 1997). 2.2.2.5 Air entrainment All concrete contains some entrapped air bubbles. Large entrapped air bubbles are undesirable. Air-entrained concrete has air, in a finely divided and dispersed form, purposely induced at the time of mixing. The air is produced in the concrete by the addition of an approved air-entraining admixture. The entrained air in the concrete, in the form of a large number of very small air bubbles in the mortar portion of the mix, is the result of the foaming action of the admixture. The principal reason for entraining air in concrete is to increase resistance to the destructive effects of freezing and thawing and deicing salts. The entrainment of air also increases the workability of the concrete for placement purposes and permits a reduction in the sand and water contents of the mix. The large number of fine bubbles increases the cohesiveness and fatness of the mix that not only improves the workability of the concrete but also eliminates, to a large extent, the undesirable properties of ordinary concrete, namely segregation and bleeding (Teyckenne et al., 1997). 2.2.2.6 Density The value of high density was addressed indirectly in connection with other related properties in concrete. The factors that contribute to high density for all types of concrete are:
Use of well-graded aggregate of the largest possible maximum size.
Minimum water content consistent with good workability.
Minimum air content consistent with adequate durability.
Thorough consolidation during placement.
2.2.3 Tests on Concrete
Slump Test 18
Compressive Strength Test
Flexural Strength Test
Rebound Hammer Test
Penetration Resistant Test
Etc.
2.2.3.1 Slump Test A slump test is a method used to determine the consistency of concrete. The consistency, or stiffness, indicates how much water has been used in the mix. The concrete slump test is used for the measurement of a property of fresh concrete. The test is an empirical test that measures the workability of fresh concrete. More specifically, it measures consistency between batches. The test is popular due to the simplicity of apparatus used and simple procedure. The Apparatus used in the test include:
Slump Cone
Tamping Rod
Scale for Measurement
The slumped concrete takes various shapes, and according to the profile of slumped concrete, the slump is termed as:
Collapse Slump
In a collapse slump, the concrete collapse completely. A collapse slump will generally mean that the mix is too wet or that it is a high workability mix, for which slump test is not appropriate.
Shear Slump
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In a shear slump the top portion of the concrete shears off and slips sideways or if one-half of the cone slides down an inclined plane, the slump is said to be a shear slump. And this is as a result of lack of cohesion if the mix
True Slump
In a true slump, the concrete simply subsides, keeping more or less to shape. however, in a lean mix with a tendency to harshness, a true slump can easily change to the shear slump type or even to collapse, and widely different values of slump can be obtained in different samples from the same mix; thus, the slump test is unreliable for lean mixes. 2.2.3.2 Compressive Strength Test Strength tests are required for the following purposes; to check the potential strength of the concrete under controlled conditions against the desired strength and to establish a strengthage relationship for the concrete under job conditions as a control for construction operations or the opening of the work. Tests made for the first purpose are referred to as standard tests and those for the second purpose are referred to as control tests. The equipment used is the compressive testing machine. The specimens must be cubes, cylindrical or prisms. 2.2.3.3 Flexural Strength Test Flexural strength is one measure of the tensile strength of concrete. It is a measure of an unreinforced concrete beam or slab to resist failure in bending. It is measured by loading 6 x 6-inch (150 x 150-mrn) con-crete beams with a span length at least three times the depth. The flexural strength is expressed as Modulus of Rupture (MR) in psi (MPa) and is determined by standard test methods ASTM C 78 (third-point loading) or ASTM C 293 (centre-point loading). These routine tests are usually made only on paving jobs and are tested at the job site. Rehabilitation projects requiring early openings may also utilize flexural tests.
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2.3 Agricultural Waste Agricultural wastes are basically unusable substances which may be either liquid or solid produced as a result of cultivation processes such as fertilizers, pesticides, crop residues and animal waste. Agricultural waste management is a part, of the ecological cycle in which everything is cycled and recycled such that an interdependent relationship is maintained in the eco-system. By waste management, all the plant wastes are placed at the right place and the right time for the best utilization in order to convert into useful products and pollution control. Globally, 140 billion metric tons of biomass is generated every year from agriculture. Ministry of New and Renewable Energy (MNRE 2009), Govt. of India estimated that about 500 Mt of crop residue is generated every year. These wastes are destroyed by burning or allowed to decay in public places in the open air creating environmental pollution. Thus by managing these crop wastes in a well-planned manner we can maintain a healthy environment for ourselves and all other living creatures. This study will highlight some of the trends that could be adopted in the agricultural waste management so that the farmers become aware and take full advantage of the various possibilities of plant waste cycling, recycling and further utilization for economic purpose (John M. Baker, et al. 2006).
2.3.1 Classification of Agro-Waste
Animal Waste
Crop Waste
Food Processing Waste
Hazardous & Toxic Waste
2.3.1.1 Animal Waste Animal waste is a highly variable material with its properties dependent on several factors: animal age and species, type of ration, production practices, and the environment. The term
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manure usually refers to feces and urine only, while animal waste commonly refers to manure with added wash water, bedding, soil, hair or spilled feed. Other agricultural wastes may similarly be mixtures of several components. Since animal waste is highly variable, periodic analysis of specific wastes at each farm would be more accurate. Animal wastes contain microorganisms and are corrosive (John M. Baker, et al. 2006). Therefore, all materials in contact, whether timber, concrete or steel, should have their surfaces treated appropriately. Processing of animal wastes prior to refeeding them their own excreta has been aimed at decreasing the disease risk, improving the nutritive status of the recycled material, increasing the flexibility of the feeding programme (i.e. better integration with waste treatment, feed mixing and storage and feed distribution.) and reducing natural prejudice of refeeding animal wastes. The processing has been done in four main ways;
Drying the waste prior to incorporating with the ration.
Ensiling or anaerobic treatment of the waste prior to distribution.
Aerobic treatment prior to incorporation with the ration.
Chemical treatment of the waste to change its nature and improve its nutritive value.
Animal Wastes includes;
Manure
Animal Carcass
Pesticides
Herbicides
2.3.1.2 Crop Waste Crop residue, traditionally considered as "trash" or agricultural waste, is increasingly being viewed as a valuable resource. Com stalks, com cobs, wheat straw and other leftovers from grain production are now being viewed as a resource with economic value. If the current trend 22
continues, crop residue will be a "co-product" of grain production where both the grain and the residue have significant value. Crop residues have traditionally been used for animal feed. In many parts of the country, beef cows are placed in corn fields after harvest to graze on the residue and any grain remaining in the field. Also, crop residues are harvested, stored and fed to livestock during the winter. Crop residues, especially straw from small grains, are used for livestock bedding (Butterworth et al., 1986). A variety of commercial uses for crop residues is in various stages of development. Crop residues can be a feedstock for composite products such as fiberboard, paper, cement, liquid fuels and others. Several straw-to-fibreboard business ventures have emerged in recent years with mixed success. Likewise, crops residues have been investigated as a feedstock for pulp for making paper. Conservative estimates indicate that there are enough crop residues to expand the supply of papermaking fiber by up to 40 percent. Crop residues can be used as a feedstock in the gasification (thermo-chemical) process for making syngas (synthetic gas) which contains carbon monoxide (CO) and hydrogen (H2). Syngas can be used for several purposes including producing electricity, producing certain chemicals and making ethanol, gasoline, and diesel. Biomass can be used in the production of biogas, which is composed mainly of methane (CH4) and carbon dioxide (C02). Biogas can be used in many parts of the world for low-cost heating and cooking. It can also be used to generate mechanical or electrical power. Biogas can be compressed, much like natural gas, and used to power motor vehicles. Crop residues can also be burned directly to produce heat and steam (Butterworth et al., 1986). 2.3.1.3 Food Processing Waste Process residues are materials left after the crop is processed into a usable resource. These residues include husks, seeds, bagasse, molasses, and roots. They can be used as animal fodder
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and soil amendment, fertilizers and in manufacturing. The major processed crops and their wastes include;
Table 2.4: Major Crops and Their Wastes
CROP
WASTE
Coconut
Fronds, Husk, Shell Hull, Husk
Coffee Corn
Cob, Stover, Stalks, Leaves
Cotton
Stalks
Nuts
Hulls
Peanuts
Shells
Rice
Hull/husk, Straw, Stalks (IJSER, 2015)
2.3.1.4 Hazardous and Toxic Waste Hazardous wastes are made of materials that are corrosive, explosive or highly flammable. This category also includes chemicals that are dangerous to humans, animals or the environment. Hazardous waste needs to be disposed of correctly by an agricultural establishment. The method of disposal depends on state regulations and the type of material involved. Being that hazardous waste can be harmful in a variety of ways, it needs to be disposed of differently than non-hazardous waste. There are three main methods for disposing of hazardous waste; The first method is to put solid hazardous waste in sanitary landfills, which are a method of waste disposal where the waste is buried either underground or in large piles. Although nonhazardous waste is often disposed of in landfills, the landfills for hazardous waste are constructed and monitored differently. Landfills for hazardous waste are made with thicker,
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impervious liners and with more heavy-duty removal systems for leaching materials. They are also constructed far from aquifers to reduce the risk of water contamination. Hazardous waste that is liquid or has been dissolved is often placed in surface impoundments, which are shallow depressions in the earth that are lined with plastic and impervious materials. The liquid hazardous waste is dumped in the impoundment and left to evaporate. Once the liquid has evaporated, the solid hazardous waste residue remains at the bottom of the impoundment and can be removed and transported to a landfill. Surface impoundments pose many risks, including contamination, and are only used for temporary processing and storage. The third method of hazardous waste disposal is deep-well injection, which is when liquid waste is injected into a well that has been created in the porous rock deep below the water table. Around nine billion gallons of hazardous waste are injected into deep wells each year in the United States. Although this method of hazardous waste disposal is designed to be long-term and keep the waste away from humans and ground water, sometimes the wells leak or are damaged and waste contaminates the water supply.
2.4 Sugarcane According to the International Sugar Organization (ISO), Sugarcane is a highly efficient converter of solar energy and has the highest energy-to-volume ratio among energy crops. Indeed, it gives the highest annual yield of the biomass of all species. Sugarcane (Saccharum spp.) is a perennial grass and one of the few plants which store its carbohydrate reserves as sucrose. Its economic value lies in the stalks, and the sugar/sucrose they contain after crushing. Sugar cane supplies more than half of the world's sugar consu1nption. In Brazil, it is moreover a major component of biofuel. Other plants producing sucrose are sugar beet, sugar maple, sorghum and a few palms. Cane and beet sugar are indistinguishable in terms of composition
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and quality, and thus serve to supplement each other. In other words, the source of the crop is of little importance as long as the final product is near pure sucrose. Sugar cane is a tropical crop requiring a hot climate. However, it also grows well in a subtropical climate. It has wider adaptability and grows well where the temperature ranges between 20 and 35 °C. It responds well to a long period of sunlight (12 to 14 hours). High humidity (80–85 %) favors rapid cane elongation during the main growth period. It requires a rainfall of between 1,100 and 1,500 mm, abundant in the months of vegetative growth followed by a dry period for ripening. Humid soils from 100 to 150 cm depth with good drainage are most suitable. It grows well in deep, well-drained soils of medium fertility of sandy loam soil textures with a pH range between 6.0 to 7.7 (IJSER, 2015).
2.4.1 Components of Sugarcane
Sucrose
Cane Trash
Bagasse
2.4.1.1 Sucrose Sucrose is used as a sweetening agent for foods and in the manufacture of cakes, candies, preservatives, soft drinks, alcohol, and numerous other foods. Sucrose is one of the oldest sweetening agents and the most used caloric sweetener, both for home and commercial use. Also known as common table sugar, brown sugar, liquid sugar, sugar, table sugar, refined sugar, or white sugar, it consists of one unit of glucose plus one of fructose linked together by α-(1→2) glycosidic bond (IJSER, 2015). Together with starch and lactose, it is one of the three most common carbohydrates taken up with diet. It is synthesized by plants through photosynthesis using as main components water, carbon dioxide (CO2) and solar energy, energy that is stored in the chemical bonds of the molecule. So, sucrose is virtually present in
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all plants, but its extraction is economically viable only from: Sugarcane; about 75% of world production comes from sugarcane, 146 million tons on 2004. Sugar beets, especially in Europe; its sucrose content, thanks to continuous selections in the last two centuries, passed from 4.5% to 16%-18%. The extraction, except for the initial steps, is very similar from both sources. 2.4.1.2 Cane Trash Cane Trash is the field residue remaining after harvesting the Cane stalk. Sugarcane trash (or cane trash) is an excellent biomass resource in sugar-producing countries worldwide. The amount of cane trash produced depends on the plant variety, the age of the crop at harvest and soil and weather conditions. Typically, it represents about 15% of the total above-ground biomass at harvest which is equivalent to about 10-15 tons per hectare of dry matter. During the harvesting operation around 70-80% of the trash is left on the field with 20-30% taken to the mill together with the sugarcane stalks as extraneous matter (IJSER, 2015). Cane trash's calorific value is similar to that of bagasse but has an advantage of having a lower moisture content, and hence dries more quickly. Nowadays only a small quantity of this biomass is used as fuel, mixed with bagasse or by itself, at the sugar mill (IJSER, 2015). The rest is burned in the vicinity of the dry cleaning installation, creating a pollution problem in sugar-producing nations. Cane trash and bagasse are produced during the harvesting and milling process of sugarcane which normally lasts between 6 to 7 months. Cane trash can potentially be converted into heat and electrical energy. However, most of the trash is burned in the field due to its bulky nature and high cost incurred in collection and transportation. Cane trash could be used as an offseason fuel for year-round power generation at sugar mills. There is also a high demand for biomass as a boiler fuel during the sugar-milling season. Sugarcane trash can also be converted into biomass pellets and used in dedicated biomass power stations or co-fired with coal in power plants and cement kilns. 27
Currently, a significant percentage of energy used for boilers in sugarcane processing is provided by imported bunker oil. Overall, the economic, environmental, and social implications of utilizing cane trash in the final crop year as a substitute for bunker oil appears promising. It represents an opportunity for developing biomass energy use in the Sugarcane industry as well as for industries /communities in the vicinity. Positive socioeconomic impacts include the provision of large-scale rural employment and the minimization of oil imports. It can also develop the expertise necessary to create a reliable biomass supply for year-round power generation. 2.4.1.3 Bagasse Bagasse is the fibrous matter that remains after sugarcane or sorghum stalks are crushed to extract their juice. It is dry pulpy residue left after the extraction of juice from sugarcane. Bagasse is utilized as a biofuel and in the manufacture of pulp and building materials.
2.5 Bagasse Bagasse is the fibrous residue left over after milling of the Cane, with 45-50% moisture content and consisting of a mixture of hard fiber, with soft and smooth parenchymatous (pith) tissue with a high hygroscopic property. Bagasse contains mainly cellulose, hemicellulose, pentosanes, lignin, sugars, wax, and minerals. The quantity obtained varies from 22 to 36% on Cane and is mainly due to the fiber portion in Cane and the cleanliness of Cane supplied, which, in turn, depends on harvesting practices. For each 10 tons of sugarcane crushed, a sugar factory produces nearly 3 tons of wet bagasse. Since bagasse is a by-product of the cane sugar industry, the quantity of production in each country is in line with the quantity of sugarcane produced (N. Chusilp, et al., 2009).
2.5.1 Uses of Bagasse
Partial Cement Replacement Material 28
Production of paper.
Production of Fuel
Packaging material
Cogeneration
Lactic Acid Production
Sieve for Separating Oil and Water
Production of Red Ceramic
Etc.
2.5.1.1 Bagasse in Fuel Production Bagasse is often used as a primary fuel source for Sugar mills; when burned in quantity, it produces sufficient heat and electrical energy to supply all the needs of a typical Sugar mill, with energy to spare. The resulting CO2 emissions are equal to the amount of CO2 that the Sugarcane plant absorbed from the atmosphere during its growing phase, which makes the process of cogeneration greenhouse gas-neutral (K. Ganesan, et al., 2007). 2.5.1.2 Bagasse as a Packaging Material Bagasse is used for our biodegradable takeaway boxes and containers, our range of disposable plates and bowls and our ice cream cups. They are:
Reasonably priced: Comparative to paper and foil products
Heat resistant up to 100˚C
Water resistant
Oil proof
Microwave safe
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2.5.1.3 Bagasse as a Paper Material Bagasse makes a great alternative to wood pulp for paper. Eco-friendly toilet paper, serviettes and bowl lids are made from a minimum of 60 % bagasse and 40% wood pulp from a certified sustainable source. They are:
Recycled raw material – sugarcane waste fibers
Elemental Chlorine free – Bleached using an elemental chlorine-free (ECF) process
2.5.1.4 Cogeneration of Bagasse Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to simultaneously generate electricity and useful heat. Cogeneration of Bagasse is one of the most attractive and successful energy projects that have already been demonstrated in many Sugarcane producing countries such as Mauritius, Reunion Island, India, and Brazil (K. Ganesan, et al., 2007). With the following Advantages; Renewable energy option that promotes sustainable development
Takes advantage of domestic resources
Increase profitability and competitiveness in the industry,
It cost-effectively addresses climate mitigation and other environmental goals. 2.5.1.5 Bagasse for Lactic Acid Production American Crystal Sugar Company {ACS) produces nearly 24 million cwt of sugar each year from its five factories in the Red River Valley. Each of the factories generates up to 1 mgd of high strength wastewater that has historically been problematic with respect to treatment and odor generation. This presents a major challenge to ACS, from both an economic and environmental perspective. The Energy & Environmental Research Centre(EERC) has 30
developed a process concept that takes advantage of the high volumes of carbohydrate wastewater to produce high-value, environmentally friendly products, while simultaneously providing environmental benefits through enhancing the operation of the existing wastewater treatment system and reducing the potential for odor generation. The overall process consists of freeze concentrating carbohydrates from mud press wastewater, followed by controlled fermentation to produce lactic acid and chemical conversion to produce lactic acid esters. The lactate esters are good solvents for polymers and resins and could replace ketones and other polar solvents used in the polymer industry. Because of their low volatility and viscosity lowering properties, they will be especially useful for inks for jet printers. alkyd resins, and high solid paints (K. Ganesan, et al., 2007). Owing to their efficiency in dissolving salts and flux as well as oils and sealants. lactate esters can be used in cleaning circuit boards and machine and engine parts. Unlike conventional solvents. lactate esters exhibit low toxicity. are biodegradable. and are not hazardous air pollutants. Another potential market is polymers prepared from lactic acid. These are Called polylactide and arc a type of polyester. Thermoplastics of this type have a variety of uses. including moldings. fibres. films and packaging of both manufactured goods and food products. Polylactides form tough, orientable. self-supporting thin films and have. therefore, been used for adhesives, safety glass. and finishes. 2.5.1.6 Bagasse Ash as a Partial Cement Replacement Material In a study, bagasse ash sample was collected from Wonji sugar factory and its chemical properties were investigated. The bagasse ash was then ground until the particles passing the 63µm sieve size reach about 85%, and the specific surface area about 4716 cm2/gm. Ordinary Portland cement and Portland Pozzolana cement were replaced by ground bagasse ash at different percentage ratios. Normal consistency and setting time of the pastes containing Ordinary Portland cement and bagasse ash from 5% to 30% replacement were investigated. 31
The compressive strengths of different mortars with bagasse ash addition were also investigated. Four different C-35 concrete mixes with bagasse ash replacements of 0%, 5%. 15% and 25% of the Ordinary Portland cement were prepared with water to cement ratio of 0.55 and cement content of 350kg/m3 for the control mix (G.C. Cordeiro, et al., 2008). The test results indicated that up to 10% replacement of cement by bagasse ash results in better or similar concrete properties and further environmental and economic advantages can also be exploited by using bagasse ash as a partial cement replacement material.
2.5.2 Composition of Bagasse The physical properties of bagasse fibers. Fibres with the highest aspect ratio will exhibit highest tensile properties provide a high surface area which is advantageous for reinforcement purposes. Table 2.5 is those of the single-cell fibers i.e., the physical properties of bagasse fibers. Table 2.5: Physical Properties of Bagasse Fibres
Property Dia(μm) Length(mm) Aspect Ratio(l/d) Moisture content (%)
Unit 10-34 0.8-2.8 76 49 (IJSER, 2015)
Table 2.6 shows the chemical composition of bagasse plant fibers and their physical properties. It is noted that cellulose is the main constituent of plant fibers followed by hemicelluloses and lignin interchangeably and pectin respectively. Cellulose is also the reinforcement for lignin, hemicellulose, and Pectin. Table 2.6: Chemical Composition of Bagasse Fibres
Property Cellulose (%) Hemicellulose (%) Lignin (%) Pectin (%)
Unit 45-55 20-25 18-24 0.6-0.8 32
Ash (%) Extractives (%)
1-4 1.5-9 (IJSER, 2015)
Table 2.7 shows mechanical properties of bagasse fibers; by which we use fibers as reinforcement for a good mechanical property of composite materials. Table 2.7: Mechanical Properties of Bagasse Fibres
Unit
Property Tensile Strength (Mpa)
180-290
Young’s Modulus (Gpa) Failure Strain (%) Density (Kg/m3)
15-19 1-5 880-720 (IJSER, 2015)
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CHAPTER THREE METHODOLOGY 3.1 Overview This section contains information about the materials and method to be adopted in this research. Since this is a research and not a new discovery we would be using methods adopted by other research papers that have worked on this same project and while working we would test the materials to be used to decide if they meet the standard requirement used by others in other studies and to conclude if the sugarcane bagasse to be used has the same chemical and mechanical composition as that used by other researchers.
3.2 Materials The materials to be used in this research include
Water
Cement
Coarse Aggregate
Fine Aggregate
Sugarcane Bagasse Ash (SCBA)
3.2.1 Water The water to be used would be gotten from Landmark University (80 7’ 28.6752”N, 50 4’ 41.5632”E), and the suitability would be checked for concrete use. The water would be checked for grease, oil, detergent, chlorine and suspended materials, the amount of water to be used would depend on the mix ratio to be used for the concrete and the volume of the concrete.
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3.2.2 Cement The cement to be used would be ordinary Portland cement and would be gotten from Dangote cement with a 42.5R grade Rapid Hardening Cement with an initial setting time of 30 minutes and a final setting time of 600 minutes and it is expected to reach a compressive Strength between 48-58MPa in 28 days. The amount of cement needed for the mix would be determined from the mix ratio.
3.2.3 Coarse Aggregate The coarse aggregate to be used would be gotten in Landmark University, Omu-Aran. the aggregate would be sieve using sieve shakers and the size to be used must be greater than 20mm in diameter and granite would be used as the coarse aggregate material, the amount of coarse aggregate to be used would depend on the mix ratio that would be used.
3.2.4 Fine Aggregate The fine aggregate must pass through a 20mm diameter sieve and the material to be used would be gotten from the Omu-Aran region and it would be the sharp sand in the area. The quantity to be used would depend on the mix ratio to be adopted.
3.2.5 Sugarcane Bagasse Ash (SCBA) This would be gotten from a sugar producing factory in the southern part of Nigeria, the bagasse would be gotten after the extraction of sucrose from the sugarcane, while the SCBA would be gotten from the burning of the bagasse in a furnace. The quantity to be used would be determined by the concrete mix and the percentage of cement replacement.
3.3 Method
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3.3.1 Mixing Method In the mixing of the concrete, we would use a mix ratio of 1:2:4, and a water-cement ratio of 0.55 due to the compressive strength of the concrete. We would replace the cement with the SCBA in three batches plus one batch of the concrete without the addition of the SCBA, so as to compare their properties with the aid of some tests. Below is a table showing the mix ratio With a compressive strength of 25N/mm2 using Ordinary Portland Cement; Water-Cement Ratio = 0.55 Concrete Mix Ratio = 1:2:4; Cement - Fine Aggregate - Coarse Aggregate Concrete Cube of 150mm x 150mm x 150mm Therefore, Volume of Cube = 3375000mm3 = 3.375x10-3 m3 Volume of Slump Cone = 5.8x10-3 m3 Four different concrete mix batches (B1, B2, B3, B4) would be made as shown in table 3.1 below using mix ratio 1:2:4, Cement = 14.29% Fine Aggregate = 28.57% Coarse Aggregate = 57.14% Table 3.1: Concrete Mix in Ratios and Percentage
Mix
B1
B2
B3
B4
Cement
1 = 14.29%
0.90 = 12.861%
0.85 = 12.146%
0.80 = 11.432%
Fine Aggregate
2 = 28.57%
2 = 28.57%
2 = 28.57%
2 = 28.57%
Coarse Aggregate
4 = 57.14%
4 = 57.14%
4 = 57.14%
4 = 57.14%
SCBA
0 = 0%
0.1 = 1.429%
0.15 = 2.144%
0.20 = 2.858%
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The amount of materials used in mix by weight would be determine as follows; Density = Weight/ Volume i.e. Total Weight of concrete = Density of concrete x Volume of concrete
3.3.2 Testing Method The concrete would be tested before and after hardening through a set of approved tests for concrete, the test would be to determine the compressive strength, consistency and durability of the concrete. The following tests would be done; 3.3.2.1 Slump Test The slump test would be used to determine the consistency of the concrete. The consistency, or stiffness, indicates how much water has been used in the mix. This test is performed on fresh concrete mix before hardening, this test would be performed on all the batches of concrete mix The Apparatus used in the test include:
Slump Cone
Tamping Rod
Scale for Measurement
The slumped concrete takes various shapes, and according to the profile of slumped concrete, the slump is termed as:
Collapse Slump
Shear Slump
True Slump
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After the experiment the consistency of the four concrete batches would be compared and the most suitable would be determined. The volume of concrete needed for each batch of this test is 5.8x10-3 m3. (refer to 2.2.3.1 for more info) 3.3.2.2 Compressive Strength Test This is done to check the potential strength of the concrete under controlled conditions against the desired strength and to establish a strength-age relationship for the concrete under job conditions as a control for construction operations or the opening of the work. Before this test is done, the concrete would be cured in water (h20) in three different categories i.e. 7days, 14days and 28days respectively and the strength obtained after curing would be compared within the four batches to determine which batch is with the highest compressive strength. The apparatus needed for this test is the compression testing machine. The volume of concrete needed for each batch is 3.375x10-3 m3. (refer to 2.2.3.2 for more info) 3.3.2.3 Durability Test Several testing methods exist for evaluating the durability of concrete and various quantitative measures are used to describe progressive damage. Most of the existing testing methods, however, have certain weaknesses or drawbacks. For example,
Change in length may not be reliable because expansion can be masked by surface scaling,
Measurements of weight may not reflect extensive microcracking, and
Measurements of resonant frequency may not reflect extensive spalling
38
But in this test we would be checking for changes in length and weight, the concrete would be cured in NaCl and H20 for seven (7) days and then allowed to dry, then the weight and length of the concrete before and after curing the concrete would be compared, and this test would be done for all the batches to determine which one resist changes more. Volume of concrete needed for each batch is 3.375x10-3 m3.
3.3.3 Curing Method This is the process of placing the concrete cube in a solution for different time periods so as to determine their properties after the process, in this study two different solutions would be used in curing i.e. NaCl and H20. And three different time periods would be used for curing i.e. 7days, 14days, 28days. Table 3.2 below would show how many batches of concrete would be cured, the time period of curing and the solution they would be cured with. Table 3.2: Concrete Curing
Time/Solution
7 Days
14 Days
28 Days
H2 0
4 batches
4 batches
4 batches
NaCl
4 batches
------------
------------
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