Compacted Foundry Sand Treated with Cement Kiln ...

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clay material for use waste containment facilities. According to research conducted on the hydraulic conductivity of CKD by chadbourne, J. and Bouse, E. (1985), ...
Compacted Foundry Sand Treated with Cement Kiln Dust as Hydraulic Barrier Material G. Moses1 and J.O. Afolayan2 1

Department of Civil Engineering Nigerian Defense Academy, Kaduna, Nigeria. [email protected]

2

Department of Civil Engineering Nigerian Defense Academy, Kaduna, Nigeria. [email protected]

Investigative laboratory tests were carried out on foundry sand treated with up to 12% cement kiln dust (CKD) by dry weight of soil to determine its suitability for use in waste containment facility. Specimens were compacted at the energy levels of British standard light (BSL), West African standard (WAS) and British standard heavy (BSH). The prepared specimens were moulded at water contents of -2%, 0%, +2% and +4% of the optimum moisture. Index properties, hydraulic conductivity (k), volumetric shrinkage strains (VSS) and unconfined compressive strength (UCS) tests were carried out. Results obtained showed slight significant change in index properties. However, hydraulic conductivity values recorded for 0% CKD treatment at West African standard and British standard heavy compactive effort met the regulatory 1x10-9m/s requirement. Furthermore, 12% CKD treatment of foundry sand at British standard heavy compactive energy level also met the regulatory requirement. The UCS values at all CKD treatment levels and all the three compactive energy level met the minimum value of 200kN/m2 except at 0% CKD treated foundry sand for BSL energy level that failed to meet the specification requirement. Recorded VSS values met the regulatory requirement of less than 4% VSS. They were achieved at al CKD treatment levels. The overall acceptance zone for CKD treated foundry sand was achieved at 0% CKD content for WAS and BSH energy level and at moulding water content range of 9.6-11.0% and 7.3-10.3% respectively. While 12% CKD content recorded successful result only at BSH compactive effort and moulding water content range of between 11.0-12.8%.

KEYWORDS:

Acceptable zone, Cement Kiln Dust, Compaction, Durability, Hydraulic conductivity, Unconfined compressive strength, Volumetric shrinkage strain

INTRODUCTION Research into new and innovation use of waste material is continually being advanced, particularly concerning the feasibility, environmental suitability and performance of the beneficial reuse of most waste materials. Some of these materials include plastics, glass, scrap tires, fly Ash, cement kiln dust etc. The concern about environmental degradation or groundwater - 337 -

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contamination led to modern engineered landfills with standard regulatory prescriptions. Compacted soil liners have been used for many years as engineered hydraulic barriers for waste containment facilities. And the trend of increasing urban population has resulted in a significant increase in waste production and has made it necessary for municipalities to use landfill space more efficiently with utilization of industrial and agricultural waste incorporated into liner systems. Other materials used as liners or cover in waste containment systems, in addition to natural clayey soils, includes, processed clay/sand-processed clay mixtures, Geosynthetic materials and industrial waste products. (Boardman and Daniel,1996; Bowders et al., 1987; Edil et al., 1995; Benson and Trast, 1995; Frebrer 1996; Abichon et al., 2000; Albrecht and Benson, 2001). Furthermore, Studies have been carried on the use of compacted lateritic soil as liners and cover in waste containment application (Osinubi and Nwaiwu, 2005, 2009; Osinubi and Eberemu, 2006; Osinubi and Eberemu, 2009a.b.; Osinubi and Amadi, 2009; Amadi, 2006 and Eberemu, 2007). Lime had been used to stabilize the hydraulic conductivity of clay against chemical attack by organic solutions (Broderick and Daniel 1990), and as an additive to reduce hydraulic conductivity of fly ash (Bowders and Daniel, 1987). In recent years, guidelines have been compiled for selecting appropriate soil properties and compaction methods that are likely to result in low hydraulic conductivity (Daniel 1990). These guidelines are typically based on experience and generally include maximum values or acceptable ranges for properties that describe composition of soil (e.g Atterberg limits, particle size distribution) and recommendations for selection of materials Cement kiln dust (CKD) is an industrial waste from cement production. The quantities and characteristics of CKD generated depend upon a number of operational factors and characteristics of the inputs to the manufacturing process. Although the relative constituent’s concentrations in CKD can vary significantly, CKD has certain physical characteristics that are relatively consistent. When stored fresh, CKD is a fine dry, alkaline dust that readily absorbs water. The ability of the CKD to absorb water stems from its chemically dehydrated nature, which results from the thermal treatments it receives in the system. the action of absorbing water (rehydrating) releases a significant amount of heat from non-weathered crust, a phenomenon that can be exploited in beneficial re-use in order to improve the inadequacy of some avoidable extensive clay material for use waste containment facilities. According to research conducted on the hydraulic conductivity of CKD by chadbourne, J. and Bouse, E. (1985), the hydraulic conductivity is inherently low at least compared to typical soil types. Compacted CKD conductivities are as low as 1x10-12 m/s, an extremely low value compared to the typical conductivity of typical clay liner, which is about 1x10-9 m/s. the highest conductivity Kunes and Smith (1983), Freber (1996), Vierbiechew Associates (1995), Abichou et al., (2000) have utilized foundry green sand with other additives such as bentonite in waste containment structures etc.. There are two basic types of foundry sand available, green sand (often referred to as moulding sand) that uses clay as the binder material, and chemically bonded sand that uses polymers to bind the sand grains together. Green sand consists of 85 – 95% silica, 0 – 12% clay (bentonite, kaolin etc), 2 – 10% carbonaceous additives, such as sea coal, and 2 – 5% water, other minor ingredients (flour, rice hulls, starches, cereals, etc.) may be added to absorb moisture, improve the fluidity of the sand, or stiffen the sand based on the production needs of the individual foundry. Green sand is the most commonly used moulding media in foundries. Large quantities of waste materials from mineral, agricultural, domestic and industrial sources are generated daily and the safe disposal of these wastes are increasingly becoming a

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major concern around the world (ETL, 1999). These wastes, if properly treated, could be modified for use as structural components of highway pavements or as waste containment materials. Research work has been carried out on the improvement of geotechnical characteristics of soils using CKD in the treatment of lateritic soil (Liman, 2009). However, no work has been done on the use of CKD treated foundry sand in waste containment applications. The study was aimed at the evaluation of the suitability of compacted foundry sand treated with CKD for use in waste containment applications; Table 1: Oxide Concentration (%)

CaO 50.81

Oxide Composition of the Cement kiln dust Al2O3 4.71

SiO2 Fe2O3 1.92

Mn2O3 0.002

Na2O 0.001

K2O 1.35

pH 11.2

Gs 2.22

MATERIALS AND METHODS Materials Foundry sand: The foundry sand used in this study was obtained from Defense Industries Corporation of Nigeria (DICON), Kaduna (Latitude 10°30’N and Longitude 7°27’E), Nigeria. Cement Kiln Dust: The cement kiln dust used was obtained from freshly deposited heaps of the waste at the Ashaka cement production plant located in Nafada Local Government Area of Gombe state, Nigeria. The CKD is brownish in color with a specific gravity of 1.90. The CKD was sieved through Bs sieve No. 200 and was stored in air-tight containers before usage. The cement kiln dust used was obtained from freshly deposited heaps of the waste at the Ashaka cement production plant located in Nafada Local Government Area of Gombe state, Nigeria. The CKD is brownish in color with a specific gravity of 1.90. The CKD was sieved through Bs sieve No. 200 and was stored in air-tight containers before usage.

Methods Index Properties: Laboratory tests were conducted to determine the index properties of the natural soil and soil – cement kiln dust mixtures in accordance with British Standards BS 1377 (1990) and BS 1924 (1990) respectively. Particle size plot of the natural soil and soil – cement kiln dust mixtures is shown in Table. 2. A summary of the soil index properties is presented in Table 2.

Compaction The compactive energy level used is the British Standard Light (BSL), West African Standard (WAS), British standard heavy (BSH). The tests involving moisture – density relationship, volumetric shrinkage, unconfined compressive strength (UCS), and hydraulic conductivity. Air dried soil samples passing through BS sieve with 4.76mm aperture mixed with 0%, 4%, 8% and 12% cement kiln dust by weight of dry soil were used. The British standard light is the effort derived from 2.5kg rammer falling through 30cm onto three layers, each

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receiving 27 uniformly distributed blows; (BS 1990) The West African standard compactive effort (WAS), carried out using energies derived from a rammer of 4.5 kg mass falling through a height of 45 cm in a 1000 cm3 mould. The soil was compacted in five layers, each layer receiving 10 blows. The WAS compaction, carried out using energies derived from a rammer of 4.5 kg mass falling through a height of 45 cm in a 1000 cm3 mould. The soil was compacted in five layers, each layer receiving 10 blows. Finally, for the BSH compaction moisture density relationships were determined using energy derived from a hammer of 4.5kg mass falling through a height of 45cm in a 1000cm3 mould. The soil was compacted in 5 layers, each receiving 27 blows. Table 2: Physical properties of foundry sand and CKD treated foundry sand Engineering Properties Liquid Limit, % Plastic Limit, % Plasticity Index, % Linear Shrinkage, % Percentage Passing BS No. 200 Sieve. AASHTO Classification USCS Classification Specific Gravity MDD Mg/m3 British Standard Light West African Standard British Standard Heavy OMC% Standard Proctor West African Standard British Standard Heavy pH Value Color Dominant Clay mineral

0 19.0 N.P. N.P. 0.9 31

Cement kiln dust (%) 4 8 19.0 19.0 N.P N.P N.P. N.P. 0.9 0.8 34 31

12 12.0 N.P N.P. 0.8 38

A-3(0) SC 2.64

A-3(0) SC 2.67

A-3(0) SC 2.69

A-3(0) SC 2.72

1.887 1.984 2.084

1.933 1.933 2.090

1.910 1.925 2.072

1.887 1.915 2.045

11.5 9.5 8.9 8.9 Brown Smectite

11.2 10.1 9.0

10.7 11.4 9.7

10.8 11.2 9.9

Hydraulic Conductivity This was measured using the rigid wall permeameter under falling head condition as recommended by Head (1992). A relatively short sample was connected to a standpipe, which provided the head of water flowing through the sample. Compacted soil – CKD samples at the different CKD contents (0%, 4%, 8% and 12%) and different moulding water contents (-2%, 0%, +2% and +4% of the OMC, respectively) using the BSL, WAS and BSH compactive efforts. Specimens were soaked in a water tank for a minimum period of 24 hours to allow for full saturation and the samples were restrained from swelling vertically during saturation. The fully saturated test specimen was then connected to a permeant liquid (tap water). During permeation, test specimens were free to swell vertically (i.e., no vertical stress was applied). Hydraulic gradient ranged from 5 to 15.Test were only discontinued when hydraulic conductivity readings were steady.

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Unconfined Compressive Strength This test was carried out in accordance with British Standards (BS 1990). Unconfined compressive strength (UCS) test were performed on cylindrical specimens 38.1mm in diameter and length of 76.2mm. This ensured testing of soil specimens with length to diameter ratio of 2. Air dried soil – CKD mixtures were compacted at – 2%, 0%, +2% and +4% of the optimum moisture content (OMC) and maximum dry density of the BSL, WAS and BSH energy levels. After each compaction, the soil was extruded from the mould and sealed in polythene bag to minimize moisture loss, and kept for a period of 48 hours to allow for uniform moisture distribution and curing, at a constant temperature of 25 ± 2ºC. After curing specimens were placed in a load frame machine driven strain controlled at 0.10%/min until failure occurred. Three specimens were averagely prepared for each test.

Volumetric Shrinkage The volumetric shrinkage upon drying was measured by extruding cylindrical specimens, compacted using the BSL, WAS and BSH energy levels. Air dried soil – CKD mixtures were compacted at – 2%, 0%, +2% and +4% of the optimum moisture content (OMC). The extruded cylindrical specimens were placed on a laboratory bench at a uniform temperature of 29 ± 2ºC for 40 days. to dry naturally. This method is considered to be better than the method used by Daniel and Wu (1993) in which compacted cylindrical specimens were made dry in an air-conditioned building. This is because natural drying in the laboratory is considered to duplicate field conditions. Measurements of diameters and heights for each specimen were taken with the aid of a vernier caliper accurate to 0.05mm. The average diameters and heights were used to compute the volumetric shrinkage strain.

DISCUSSION OF RESULTS Index properties The index properties are shown on table.3. The liquid limit (LL) as shown in Fig.1 showed little in value from 19 to 12%. An increase was observed until a maximum value of 23.3% was attained at 4% CKD content; this increase can be attributed to the increase in CKD which introduced more pozzolanic substance into the specimen that required more water for hydration to be completed. After 4% CKD content a decline in liquid limit value was observed up till 12% CKD content. This decrease can be associated with the agglomeration and flocculation of the clay particles which is as a result of exchange ions at the surface of the clay particles. Foundry sand has been reported Johnson (1981) as possessing no plasticity, this is largely due to the presence of a high percentage of fine sand (85%), and the addition of CKD produced little or no change to this condition. Plasticity index values varied in the same pattern with the liquid limit. The addition of CKD to foundry sand did not have any significant change in the linear shrinkage this can be expected as the soil in question already posses signicant amount of fine sand which has no expansive or swelling tendency.

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Compaction Characteristics Maximum dry density

Maximum dry density (Mg/m3)

The variation of maximum dry density (MDD) for soil-CKD mixes are shown in Fig.1. The BSL, WAS and BSH compactive effort generally showed a decrease in MDD with higher CKD content, which is in agreement with Yoder and Witzack (1975). They reported that cement also decreases the density of soils and the same result can be expected of cement kiln dust since it is waste generated from the production of cement. . Furthermore, there is a possibility that the decrease in MDD is as a result of CKD which has a low specific gravity (2.2) replacing the soil particles which has a higher specific gravity of 2.58.

2.15 2.1 2.05

BSL WA

2

BSH

1.95 1.9 1.85 0

2

4

6

8

10

12

CKD (%)

Figure 1: Variation Maximum Dry Density With CKD

Optimum moisture content The variation of OMC with for BSL, WAS and BSH compaction are shown in Figs. 4 - 6. There was generally an increase in OMC with higher CKD contents for the West African standard and British standard heavy compactive efforts. It also could be due to the larger amounts of water required for the hydration of CKD. These results are in agreement with those reported by Nicholson and Kashyap (1993). The decrease in OMC observed for specimens compacted at the BSL compactive efforts was probably due to self – desiccation in which all the water was used, resulting in low hydration. When no water movement to or from CKD – paste was permitted, the water is used up in the hydration reaction, until too little is left to saturate the solid surfaces and hence the relative humidity within the paste decreases. The process described above might have affected the reaction mechanism of the CKD treated specimen (Osinubi, 2000).

Optimum Moisture Content (%)

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14 13 BSL

12

WA

11

BSH

10 9 8 0

2

4

6

8

10

12

CKD (%)

Figure 2: Variation of Optimum Moisture Content with CKD

Hydraulic Conductivity Hydraulic conductivity is the key parameter affecting performance of liners and cover (Daniel 1987, 1990).The relationship between hydraulic conductivity and moulding water content is shown in Fig.3. Generally the hydraulic conductivity obtained its lowest value at the wet side of compaction, especially at +2% OMC for most of the specimen. Beyond +2’ OMC and before +2% OMC there is generally an increase in hydraulic conductivity values. The increasing moulding water content facilitates deflocculating of the particle structure, reducing the void. This is in conformity with other research works (Lambe, 1959; Mitchell et al., 1965; acer and Oliver; 1989, Garcia – Bengochea et al., 1979; Benson and Daniel, 1990; Osinubi and Nwaiwu, 2005; Osinubi and Eberemu, 2009b). Increasing moulding water content from the dry to the wet side affects the hydraulic conductivity. The variations of hydraulic conductivity with water content as shown in Fig.3, The result obtained for the untreated foundry sand sample compacted between -2 to +4% OMC British Standard light, West African Standard and British standard heavy gave satisfactory hydraulic conductivity values less than 1×10-9m/s (Benson and Daniel, 1990; Eberemu 2007 and Osinubi and Nwaiwu, 2005; Osinubi and Eberemu, 2009b). These minimum specified values were obtained at a moulding water content of 10.7 – 13.7%, 9.6-13.5% and 7.3-12.3% respectively. All other CKD treatments levels did not give successful hydraulic cinductivity values except at 12% CKD treatments levels for WAS and BSH energy levels at moulding water contents of 12.913.9% and 11.0 – 12.8% respectively. This could be as a result of the CKD displacing the bentonite clay & fines in the foundry sand thus making specimen incapable to satisfy hydraulic conductivity specification values based on researches which have specify minimum clay content of 15% & 30% fines (Daniel, 1993b; Benson et. al., 1994) for specimens of soil samples that will yield acceptable hydraulic conductivity values; (Benson et.al. 1994). Generally higher compactive efforts yield results that are consistent with other research works (Eberemu, 2007; Osinubi and Nwaiwu, 2005; Osinubi and Eberemu, 2009b).

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Hydraulic conductivity (m/s)

1.00E-06 0% CKD

1.00E-07

4% CKD 8% CKD

1.00E-08

12% CKD 1.00E-09 1.00E-10 6

8

10

12

14

16

18

Moulding water content (%)

Figure 3: Variation of hydraulic conductivity with moulding water content for BSL Compactive Effort

Hydraulic conductivity (m/s)

1.00E-06 1.00E-07

0% CKD 4% CKD

1.00E-08

8% CKD 1.00E-09

12% CKD

1.00E-10 1.00E-11 6

8

10 12 14 Moulding water content (%)

16

18

Figure 4: Variation of hydraulic conductivity with moulding water content for WAS Compactive Effort

Hydraulic conductivity (m/s)

1.00E-06 0% CKD

1.00E-07

4% CKD 1.00E-08

8% CKD

1.00E-09

12% CKD

1.00E-10 1.00E-11 6

8

10

12

14

16

18

Moulding water content (%)

Figure 5: Variation of hydraulic conductivity with moulding water content for BSH Compactive Effort

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Volumetric Shrinkage Strain Researchers such as Daniel and Wu (1993) and Tay et al. (2001) suggested a safe VSS value of less than or about 4% volumetric shrinkage strain (VSS) upon drying for soil liners when compacted cylinders as used to predict field desiccation due to cracking. The variation in VSS with moulding water content are shown in Figs. 6 through 8. Generally as the CKD content increases for each energy level there is a decrease in the desiccation induced volumetric shrinkage strain. Specimen compacted at greater moulding water content shrank more during drying which is consistent with the results of Daniel and Wu (1993), Albrecht and Benson (2001). The reasons for this is not farfetched because dry shrinkage in fine grained soils according to Mitchell (1976) depends on particle movement as a result of pore water tension developed by capillary menisci.

Volumetric shrinkage strain (%)

For the untreated foundry sand compacted between – 2% to +4% of the OMC produced satisfactory results at BSL, WAS and BSH compactive efforts. Progressive treatment of specimen generally showed a decline in the desiccation induced volumetric shrinkage strain; this behavior can be attributed to the pozzolanic input of the CKD which reduces the fine grained soils and bind the particles much closer together. there is a decline in the volumetric strain is observed at OMC with increasing CKD content. This is largely attributed to the pozzolanic input of CKD (Osinubi and Steven, 2005). Furthermore, higher compactive effort produced less volumetric strain this is consistent with previous works (Haines, 1923; Albrecht, 1976; Albrecht and Benson, 2001; Osinubi and Nwaiwu, 2005; Osinubi and Eberemi 2008b, 2009a)

8 7

0% CKD

6

4% CKD

5

8% CKD

4

12% CKD

3 2 1 0 8

10 12 Molding water content (%)

14

16

Figure 6: Variation of volumetric shrinkage strain with molding water content at BSL compactive effort

Volumetric shrinkage strain (%)

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6 5 4 3 2 1 0 -1 -2

0% CKD 4% CKD 8% CKD 12% CKD

6

8

10 12 14 Molding water content (%)

16

Volumetric shrinkage strain (%)

Figure 7: Variation of volumetric shrinkage strain with molding water content at WAS compactive effort 6 0% CKD 4% CKD 8% CKD 12% CKD

5 4 3 2 1 0 -1 6

8

10 12 14 Molding water content (%)

16

Figure 8: Variation of volumetric shrinkage strain with molding water content at BSH compactive effort

Unconfined Compressive Strength Daniel and Wu (1993) arbitrarily selected a minimum of 200kN/m2 as the minimum required strength of soil to be used in compacted soil liners required to support the maximum bearing stress in a landfill. The variations of unconfined compression test with water content are shown in Fig.9-11, the shear strength of the untreated foundry decreases with increasing moulding water content. As the moulding water content increases electrolyte concentration is reduced, an increased diffused double layer expansion takes place and the distance between clay particles as well as the distance between the alumina-silicate unit layers increases, resulting in a reduction of both the internal friction and cohesion (Seed and Chanlasa; Daniel and Wu 1993;Taha and Kabir 2005). But for treated samples there are slight variations due to the fact that for any pozzolana there is an optimum mix of water to produce maximum strength as has been observed by previous researchers (Osinubi et al., 2008) minimum UCS value specified by Daniel and Wu, (1993) were not satisfied for the untreated foundry sand at BSL compactive effort. However, WAS and BSH compactive efforts gave satisfactory results. The trend of the untreated foundry sand is consistent with other research work on soils (Daniel and Wu, 1993; Osinubi and Nwaiwu, 2005; Osinubi and Eberemu, 2009a).

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Unconfined compressive strength (kN/m2)

However, specimens of higher CKD treatment contents yielded lesser values especially on the dry side of optimum at WAS and BSH compactive effort compared to those obtained at lower treatment level.

415 365 315 265 215 165 115 65 15

0% CKD 4% CKD 8% CKD 12% CKD

8

10 12 14 Molding water content (%)

16

Unconfined compressive strength (kN/m2)

Figure 9: Variation of unconfined compressive strength with molding water content at BSL compactive effort 400 0% CKD 4% CKD 8% CKD 12% CKD

350 300 250 200 150 100 6

8

10 12 Molding water content (%)

14

16

Unconfined compressive strength (kN/m2)

Figure 10: Variation of unconfined compressive strength with molding water content at WAS compactive effort 600 0% CKD 4% CKD 8% CKD 12% CKD

500 400 300 200 100 6

8

10 12 14 Molding water content (%)

16

Figure 11: Variation of unconfined compressive strength with molding water content at BSH compactive effort

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ACCEPTABLE ZONES Stewart et al. (1999) recognized that the parameters for the design of soil liners and covers include a low hydraulic conductivity, low desiccation-induced volumetric shrinkage strain and high value of unconfined compressive strength. Daniel and Benson (1990), developed a relationship between the dry density and moulding water content that will satisfy the three parameters. For the hydration conductivity the acceptable limit was set at less or equal to 1 × 10-9 m/s, the volumetric shrinkage strain was set at a value of less or equal to 4% and the unconfined compressive strength value is set at 200 kN/m2 or more the compaction plane was arrived at by using the average shrinkage strain test specimens. And final after an acceptable zone for each of the parameters has been for each CKD treatment by superimposing the various acceptance zone of each of the parameters has been determined and overall acceptance zone is determined the various acceptance zone of each of the individual parameter to produce an overall acceptance that covers all the specification requirements of the individual parameters. Table 3: Acceptable ranges of moulding water contents at BSL energy level Engineering Criteria

Cement Kiln Dust Content, % 0

4

8

12

Moulding Water Content Range, % k, m/s

10.7-13.7 2

UCS, kN/m VSS, %

9.5-12.6

9.2-12.1

8.7-12.8

9.2-13.2

8.7-13.2

8.8-14.8 8.8-14.8

OAR

OAR – Overall Acceptable Range Table 4: Acceptable ranges of moulding water contents at WAS energy level Engineering Criteria

Cement Kiln Dust Content, % 0

4

8

12

Moulding Water Content Range, % k, m/s

9.6-13.5 2

12.9-13.9

UCS, kN/m

7.5-11.0

8.1-12.8

9.4-13.5

9.2-13.5

VSS, %

7.5-12.1

8.1-14.1

9.2-15.2

6.9-12.9

OAR

9.6-11.0

OAR – Overall Acceptable Range

OVERALL ACCEPTABLE ZONE The design of liners and cover in waste containment facility involves arriving at a convergence of moulding water content of three important design parameters. At this range of moulding water content the regulatory specified values of the hydraulic conductivity, unconfined compressive strength and volumetric strain shrinkage must be met. Thus, an overall acceptance zone of moulding water content and maximum dry density satisfactory for all the design parameters is produced (as shown in Fig.12 and 13).

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Table 5: Acceptable ranges of moulding water contents at BSH energy level Engineering Criteria

Cement Kiln Dust Content, % 0

4

8

12

Moulding Water Content Range, % k, m/s

7.3-12.3 2

11.0-12.8

UCS, kN/m

6.3-10.3

7.0-12.5

7.7-13.0

7.9-13.9

VSS, %

6.9-12.0

7.0-13.0

7.7-13.5

7.9-13.9

OAR

7.3-10.3

11.0-12.8

OAR – Overall Acceptable Range

Maximum dry density (Mg/m3)

The satisfactory treatment level of CKD treated foundry sand that gave an overall acceptance range for all the three established criteria were achieved at 0% CKD and 12% CKD. And they were achieved at a moulding water content range of 7.3-10.3% and 11.0 -12.8 respectively.

2.4

Volumetric strain 2.3

Overall Acceptable Zone

Hydraulic Conductivity

2.2

Shear Strength

2.1

Volumetric Strain

2

Zero Air-Void Line

1.9

Hydraulic conductivity

Shear strength

1.8 1.7 4

6

8

10

12

14

16

18

Moulding Water Content (%)

Figure 12: Overall acceptable zone at 0% CKD treatment Overall Acceptance Zone

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Maximum dry density (Mg/m3)

2.4

Volumetric strain

2.3

350

Hydraulic Conductivity

Overall Acceptable Zone

Shear Strength 2.2 Volumetric Strain 2.1 Zero Air-Void Line 2 1.9

Hydraulic conductivity

Shear strength

1.8 5

7

9

11

13

15

17

Moulding Water Content (%)

Figure 13: Overall acceptable zone at 12% CKD treatment Overall Acceptance Zone

CONCLUSION AND RECOMMENDATION Inclusion suitability of cement kiln dust for the treatment of foundry sand as a compacted hydraulic barrier material proofed successful. Slight changes in the index properties of the cement kiln dust treated foundry sand specimen. However, the MDD generally increased with increasing CKD content while the OMC decreased with increasing CKD content. In other to determine a suitable acceptance zone for the three important parameters (hydraulic conductivity, unconfined compressive strength and desiccation induced volumetric shrinkage strain Specimens were compacted at -2%, 0% +2% and +4% of the optimum moisture content at the energy levels of British standard light, West African standard and British standard heavy compactive effort). An assessment to produce a converging MDD and OMC that will produce covers and liner that meets the specification requirements of widely accepted standards of the three important parameters were designed. Hydraulic conductivity produced acceptable results at both BSL and WAS compactive efforts. Generally, a decline of hydraulic conductivity with increasing moulding water content and increasing compactive energy level were observed.. For the UCS, the result show a general improvement in strength for up to 12% CKD treatment this is largely as a result of the pozzolanic input of CKD which produced stronger bonds. Treated foundry sand produced improved volumetric shrinkage strain values at both BSL, WAS and BSH compactive efforts with regulatory minimum VSS values achieved at all treatment levels. Finally, the recommended overall acceptance zone that produced a convergence of the specification requirements of the three important parameters for the design of liners and covers were achieved at 0% CKD and 12% CKD treatment of foundry sand WAS and BSH compactive effort, and at moulding water content ranges of 7.3-10.3% and 11.0-12.8 respectively.

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REFERENCES 1. AASHTO (1986) Standard specification for transportation materials and methods of sampling and testing, 14th Ed., Washington, D.C. 2. Abichou, T., Benson, C.H. and Edil, G. T. (2000) “Foundry green sand as hydraulic barriers laboratory studies.” J. of Geotech. and Geoenvironmental Engrg. ASCE, Vol. 126. pp 1174 – 1183 3. Abichou, T., Benson, C.H. and Edil, G. T. (2004) “Network model for hydraulic conductivity of sand bentonite mixture” Canadian Geotech Journal. 41 (4), 698 – 712. 4. Acar, Y. and Oliveri, I. (1989). “Pore fluid effects on the fabric and hydraulic conductivity of laboratory compacted clay.” Transportation Research Record, Vol. 1219, pp. 144 – 159. 5. Albrecht B. (1976) “Effect of desiccation on compacted clay”. M. Sc thesis, university of Wisconsin, Madison, Wisconsin, U.S. A. 6. Albrecht, B. A. and Benson, C. (2001) “Effect of desiccation on compacted natural clay.” J. Geotech and Geoenvir. Engrg., ASCE, Vol. 127, No. 1, pp. 67 – 75. 7. ASTM (1992) Annual book of ASTM standards, Vol. 04. 08, Philadelphia. 8. Benson, C. H. and Daniel, D. E. (1990) “Influence of clods on hydraulic conductivity of compacted clay.” J. Geotech. Engrg., ASCE Vol. 116, No. 8, pp. 1231 – 1248. 9. Benson, C.H. and Trast, J. (1995) “ Hydraulic Conductivity of Thirteen Compacted Clay.” J. Geotech Eng’rg. ASCE Vol. 116, No.8, pp.1231 – 1248. 10. Bowders, J. and Daniel, D. (1987) “Hydraulic conductivity of compacted clay to 11. dilute organic chemicals.” J. of Geotech. Engrg., Vol. 113. No. 12, pp. 1432-1448. 12. Boardman, B. T. and Daniel, D. E. (1996) “Hydraulic conductivity of desiccated geosynthetic clay liners.” J. of Geotechnical Engineering, vol. 122, no. 3, ASCE. Pp. 204 – 208. 13. Broderick, G. and Daniel, D.E. (1990) “Stabilizing compacted clay against chemical attack.” J. of Geotech. Engrg., ASCE, Vol. 116, No. 10, pp. 1549 – 1567. 14. BS 1377 (1990) Methods of Testing Soils for Civil Engineering Purposes. British Standard Institute, London. 15. BS 1924 (1990) Methods of Tests for Stabilized Soils. British Standard Institute, London. 16. Daniel, D. E. (1993b) “Clay Liners”, In Geotechnical Practice for Waste Disposal, (ed. David E. Daniel) Chapman & Hall, London, UK, pp 137-163 17. Daniel, D. E. and Benson, C. H. (1990) “Water Content density criteria for compacted soil liners.” J. Geotech. Engrg., ASCE, Vol. 166. No. 12, pp. 1811 – 1830. 18. Daniel, D. E. and Wu, Y. K. (1993) “ Compacted clay liners and cones for arid site.” J of Geotech. Eng’rg. ASCE. Vol. 119, no. 2. pp. 223 – 237. 19. Eberemu, A. O. (2007) “Evaluation Compacted Lateritic Soil Treated With BagasseAsh as Hydraulic Barriers in Municipal Solid Waste Containment Systems” l. Unpublished PhD Thesis, Department of Civil Engineering, Ahmadu Bello Univesity, Zaria.

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20. ETL 1110-3-503 (1999) “Use of waste materials in pavement construction.” Engineering Technical Letter, B-1 to B-22. 21. Freber, B.W. (1996) “Beneficial reuse of selected foundry waste material.” Proc.of 19th International Madison Waste Conference, Madison, WI, No 13, Sept,, pp 246 – 257. 22. Garcia Bengochea, I., Lovell, and Altschaeffl, A. (1979) “Pore Distribution and Permeability of Silty Clays” J. Geotech. Engrg. ASCE, 105(7) pp. 839 – 856. 23. Haines, W. (1923) “The volume changes associated with variation of water content in soils.” Journal of Agric Science, Vol. 13, pp. 296 – 310. 24. Head, K. H. (1992) Manual of Soil Laboratory Testing, Vol. 2. Permeability, Shear Strength and Compressibility Tests. Pentech Press, London. 25. Ijimdiya, S. (2009) “Evaluation Compacted Black Cotton Soil Treated With Bagasse Ash as Hydraulic Barriers in Municipal Solid Waste Containment Systems.” Unpublished PhD Thesis, Department of Civil Engineering, Ahmadu Bello Univesity, Zaria. 26. Lambe, T. W. (1958) “The structure of compacted clay” Journal of Soil Mechanics and Foundation Engineering Division, ASCE, Vol 84, No. 2, pp. 1 – 35. 27. Liman, A. (2009) “Evaluation Compacted Lateritic Soil Treated With Cement Kiln Dust as Hydraulic Barriers in Municipal Solid Waste Containment Systems.” Unpublished MSc Thesis, Department of Civil Engineering, Ahmadu Bello Univesity, Zaria. 28. Moses, G. (2008) “stabilization of black cotton soil with ordinary portland cement Using Bagasse ash as admixture” IRJI Journal of Research in Engrg. Vol.5 No.3 , pp. 107-115 29. Oriola, F. and Moses, G. (2010). “Groundnut Shell Ash Stabilization of Black Cotton Soil” Electronic Journal of Geotechnical Engineering. Vol. 15, Bund, E 415-428. 30. Mitchell, J. K. (1976) Fundamental of Soil Behaviour. John Wiley and Sons, Inc. 31. Nicholson, P. G. and Kashyap, V. (1993) “Fly-ash stabilization of tropical Hawaiian soils.” In: Fly Ash for Soil Improvement. Ed. By Kevan D. Sharp. Geot. Spec. Pub. No. 36, pp. 15 – 29. 32. Osinubi, K. J. and Amadi, A. A. (2009) “Hydraulic Performance of Compacted Lateritic Soil Bentonite Mixtures Permeated with Municipal Solid Waste Landfill Leachete.” Transportation Reseach Board (TRB) 88 Annual Meeting CD-ROM 11-15 January, Washington DC, U.S.A. Subject. Geology and Earth Materials, Session APP40-PhysicoChemical and Biological Process in Soils Committee, Paper 409-0620, pp 1-18. 33. Osinubi, K. J. and Nwaiwu, C. M. (2005) “Hydraulic conductivity of compacted lateritic soils.” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 131, No. 8, pp. 1034 – 1041. 34. Osinubi, K. J. and Eberemu, A. O. (2006) “Hydraulic conductivity of lateritic soils treated with blast furnace slag.” Electronic Journal of Geotechnical Engineering. EJGE, Vol. 11. Bundle D, pp. 1 – 21. 35. Osinubi, K. J. and Nwaiwu, C. M. (2006) “Design of compacted lateritic soil liners and covers.” Journal of Geotech and Geoenvironmental Engineering, ASCE Vol, No. 2, pp. 203 – 213.

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36. Osinubi, K. J. and Nwaiwu, C. M. O. (2009) “Desiccation-induced Shrinkage in Uncompacted Lateritic Soils.” Journal of Geotechnical and Geological Engineering, GEGE, Spriger, Netherlands, Vol. 26, pp 603-611 37. Osinubi, K. J. and Ijimdya, T. S. (2008) ‘Laboratory investigation of engineering use of bagasse ash.’ Nigerian Society of Engineers Technical Transactions, Vol. 43, No. 1, pp. 1-17. 38. Osinubi, K. J. and Eberemu, A. O. (2009a) “Compatibility and attenuative properties of laterite-blast furnace slag mixtures.” Journal of Waste Technology and Management, Vol. 35, No. 1, pp. 7 – 16. 39. Osinubi, K. J., Eberemu, A. O. (2009b) “Desiccation-induced Shrinkage of Compacted Lateritic Soil treated with bagasse ash.” The Twenty-Fourth International Conference on Solid Waste Technology and Management CD-ROM, 15-18 March, Philidelphia, PA, U.S.A. Session 5C: Bio-reactors and Innovative Landfills, pp.856-867. 40. Shackelford, C. D. (1996) “Geotechnical design consideration for tailing dams”. Proc. of the international Symposium on Seismic and Environmental Aspects of Dam Design; Earth, Concrete and Tailing Dams. Vol. I. Santiago, Chile, Oct. 14 – 18, 1996. 41. Seed, H.B., and Chan, C.K. (1959) “Structure and Strength Characteristic of Compacted Clays.” J. of Soil Mechanics and Foundation Eng’rg, vol. 85, No.SM5, ASCE. Pp. 87 – 128. 42. Stewart. D.I., Cousens, T.W., Studds, P.G., and Tay. Y.Y. (1999) “Design parameters for bentonite-enhanced sand as a landfill liner.” Proc. Inst. Civ. Eng., London. Geotech. Eng., 137. 187-195. 43. Taha, M.R., andKabir, M.H (2005) “Assessment of Physical Properties of a Granite Residual Soil as an Isolation Barrier.” Electronic Journal of Geotechnical Engineering. EJGE, vol 60, pp 263-274. 44. Warren, K.W. And Kirby, T.M. (2004) “Expansive Clay Soil A Wide Spread And Costly Geohazard”, Geostra, Geoinstitute Of The American Society Of Civil Engineers 45. Yoder, E. J. and Witczak, M. W. (1975) Principles of Pavement Design. John Wiley and Sons. Inc. New York, 300 – 321

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APPENDIX PROGRAM KNICK C C C C C C

C C C C C C

C C C

10 C C 20

THIS PROGRAM EVALUATES THE RELIABILTY OF FONDRY SAND TREATED WITH BAGASSE ASH FOR POTENTIAL USE AS LINER MATERIAL BAESED ON THE REGULATORY MAXIMUM HYDRAULIC CONDUCTIVITY IMPLICIT DOUBLE PRECISION (A-H,O-Z) THE SUBROUTINE WITH THE LIMIT STATE FUNCTION IS DECLARED EXTERNAL EXTERNAL GKNICK DIMENSION X(5), EX(5), SX(5), VP(5,5),COV(5,5),ZES(3), 2 UU(5), EIVEC(5,5), IV(2,5) CHARACTER*10 PRT THE COMPACTIVE EFFORTS INDICES E FOR THE COMPACTED SOILS ARE SET FOR THE PROGRAM AND SUBROUTINE IN THE FOLLOWINT COMMMON BLOCK COMMON/CKNICK/E THE MEAN AND STANDARD DEVIATION OF THE VARIABLE AS WELL AS PARAMETERS OF FORMS ARE GIVEN IN THIS DATA BLOCK DATA EX/1.23D-8, 1.0D0, 75.67D0, 4.0D0, 27.7D0/, 2 SX/2.1D-8, 2.26D0,13.67D0, 2.85D0, 1.71D0/, 3 N/5/, NC/5/,NE/5/,IRHO/0/ WRITE(*,*) 'ENTER VALUE FOR E' READ(*,*)E THE RESULTS ARE WRITTEN ON FILE NO.7 NAUS=7 PRINT TO SCREEN ICRT=0 OPEN(7, FILE='MOSES.RES', STATUS='OLD', ERR=10) GO TO 20 OPEN(7, FILE='MOSES.RES', STATUS='NEW')

PRESETTING VARIABLES VP AND IV IS DONE USING YINIT CALL YINIT (N,IV,VP,IRHO,COV,NC) IV(1,1)=3 IV(1,2)=3 IV(1,3)=3 DO 100 I=1,N 100 X(I)=EX(I) V1=1.D0 BETA=1.D0 C INITIAL-SOLUTION ESTIMATE (IF NOT MEAN VALUES, SEE LOOP "100") 5000 FORMAT(////, 5X, 70('*'), /, 30X, 'FORM',/, 5X, 70('*'), 2/, 5X,' EVALUATE USING "GKNICK", 5 VARIABLES:') C THE STOCHASTICAL MODEL IS PRINTED USING "KOPF" CALL YKOPF(NAUS,N,IV,EX,SX,VP,IRHO) C PRINT ALSO TO SCREEN PRT = 'COV' CALL YMAUS (NAUS,NC,N,COV,PRT) WRITE(ICRT,*) 'STOCHASTIC MODEL'

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THE MAIN SUBROUTINE IN FORM IS CALLED CALL FORM5 (N, IV, EX, SX, VP,GKNICK, IRHO, COV, NC, EIVEC, NE, 2 V1, NAUS, BETA, X, UU, ZES, IER) THE COORDINATES OF THE BETA-POINT ARE PRINTED WITH THE TITLE VECTOR UU PRT='UU' CALL YFAUS (NAUS, N, UU, PRT) THE VECTOR ZES IS PRINTED WITH THE TITLE VECTOR ZES PRT='ZES' CALL YFAUS (NAUS, 3, ZES, PRT) WRITE(ICRT,*) 'END OF FORM: IER=', IER WRITE(ICRT,*) 'RESULTS SEE FILE MOSES. RES' STOP END STATE FUNCTION PROGRAM SUBROUTINE GKNICK(N, X, FX, IER)

C

C

IMPLICIT DOUBLE PRECISION (A-H, O-Z) DIMENSION X(N) COMMON/CKNICK/E CHECK FOR ERRORS, CALCULATE FX IF (X(1).GT.0. AND.X.GT.0.AND.X.GT.0.AND.X.GT.0) THEN FX=X(1) - ALOG(-17.4-0.265*X(2)-0.0507*X(3)+0.391*X(4) 2 +0.010*X(5)-0.326*E) IER=0 ELSE FX=1.0D+20 IER=1 ENDIF RETURN END

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