Effect of Compactive Effort and Elapse Time on the Strength of Lime-Bagasse Ash Stabilized Expansive Clay from Gombe

Ochepo, J.* and Osinubi, K. J. Department of Civil Engineering, Ahmadu Bello University, Zaria, Nigeria *Corresponding Author; e-mail: [email protected]

ABSTRACT This study was carried out to investigate the effect of compactive efforts and elapse time strength and durability of black cotton soil-lime-bagasse ash mixes. The soil obtained from Gombe, Nigeria, was treated with lime and bagasse ash in stepped concentration of 0, 2, 4, 6 and 8% by dry weight of the soil. The results obtain shows that the recommended peak values of UCS were obtained at 6 % lime/ 8 % bagasse ash treatment regardless of compactive effort used. The UCS of specimens generally increased with higher compactive efforts and curing age while a decreased in UCS was observed with elapse time for all compactive efforts, curing age and lime-bagasse ash treatment. An average of about 22 -29% decrease in strength for an elapse time of 3 hours was observed for the entire specimen tested. Durability assessment of the soil-lime-bagasse ash mix showed that the resistance to loss in strength values of tested specimens fell far short of the acceptable conventional 80 %. It was observed that sample stabilized with 6% lime/8% bagasse ash did not achieve the required UCS value of 1034.25 kN/m2 normally utilized as criterion for adequate lime stabilization after 7 days. However the UCS value at 28days curing age showed that the strength development of lime/bagasse ash is a slow process and a longer period is required to attain the specified strength.

KEYWORDS:

Delay after mixing; Durability; Moisture-Density Relationship; Unconfined Compressive Strength; Bagasse ash; Elapse time

INTRODUCTION Expansive clays are known to exhibits dual characteristics of excessive swelling and shrinkage under different moisture conditions. This swelling-shrinkage characteristic of expansive soils which depends on the stress and suction history of the soil causes deformations which are significantly greater than elastic deformations and cannot be predicted by the classical elastic or plastic theory. The movement is usually in an uneven pattern and of such magnitude as

- 219 -

Vol. 18 [2013], Bund. B

220

to cause extensive damage to the structures and pavements resting on them (Nelson and Miller, 1992). In Gombe state and other states in the Northeastern part of Nigeria where these soils are found, the characteristic features of the soil behaviors which are majorly extensive cracks are obvious on road pavements and building structures. The cost implications of these defects/failure run into many millions of naira. Many ground improvement techniques have been employed to curb or reduce the severity of the damages caused by expansive soils on civil engineering facilities; among which are lime and cement stabilization. Lime and cement are widely used for treatment of cohesive soils with expansive properties due to their effectiveness in reducing expansive properties, increase strength, decrease plasticity index, swell and shrinkage strain potential and controlling volume change. (Chen, 1988; Hausmann, 1990; Osinubi, 1995). Lime has however been considered to be more appropriate for the stabilization of clay soils having fine contents in excess of 25 % as it makes the soils more friable, less plastic and hence easier to work. The reactions of lime with soils lead to strength gain. The strength gain arises chiefly from chemical reactions between the lime, clay-grade minerals and amorphous constituent in the soil. When these are absent or present in small amounts, use has been made of lime together with a pozzolan. Pozzolanic material such as fly ash has been extensively employed in lime stabilization of soils. Osinubi (1995) reported improvement in the properties of black cotton soil stabilized with cement admixed with pulverized coal bottom ash. Similarly, Osinubi and Medubi (1998) reported improvement in the properties of soil-cement admixed with phosphatic waste. Also, Nicholson et al. (1994) reported that lime-fly ash admixture has shown tremendous potential as an economic method to update the geotechnical properties of tropical Hawaiian soil. Bagasse ash has been reported to posses pozzolanic properties (Mohammedbhai and Baguant, 1985). It was reported that bagasse ash contains a large amount of silica and other relevant oxides which enhance good pozzolanic activity (Mohammedbhai and Baguant, 1985). The ash has been used alone or as admixture with lime and cement to stabilize laterite and black cotton soils, (Osinubi and Stephen, 2005; 2006a,b,: Osinubi and Alhaji, 2005; Osinubi et al., 2008) Going by the daily increase in the prices of cement and lime in a developing country like Nigeria, the effective utilization of bagasse ash for engineering purpose is of significant economic importance. A successful employment of bagasse ash as admixture in lime stabilization, would lead to reduction in the amount of lime that may be required for a given project; hence a cut in the cost of the project. This is in addition to ridding the environment of the deleterious effect of these wastes on the environment. Soil compaction is the process by which soil is mechanically densified by pressing the soil particles together in a close state of contact, with air being expelled from the soil mass. Compaction increases the strength properties of soil, decrease permeability, settlement and increase stability of slopes. The effect of compaction is not the same for all soils as they are affected by some variables, one of which is the compactive efforts used. Higher compactive efforts results in higher energy and greater density. For soil lime bagasse ash mixture, it has been reported that higher compactive effort results in higher maximum dry density and lower optimum moisture content, (Osinubi, 1998; Osinubi et al., 2008). Elapse times between mixing and compaction have been reported to affect negatively on the final strength of soil-lime mixture (Mitchell and Hooper, 1961; Osinubi, 1998a, b; 1999b; Osinubi and Katte, 1997; 1999). It was reported that samples compacted within 1 hour after

Vol. 18 [2013], Bund. B

221

mixing had higher strength than those compacted after 24 hours. Osinubi and Nwaiwu (2006) reported a decrease in maximum dry density and California bearing ratio (CBR) when compaction was delayed after mixing. Thus for all practical purposes, delays after mixing of soil-lime mixture adversely affected the strength development of the mix. How does elapse time affects density and strength development of soil-lime-bagasse ash? This study sought to establish the effect of a maximum delay of three hours after mixing on the strength and durability properties of soil-lime-bagasse ash mixture.

MATERIALS AND METHODS Materials Soil: The clay used in this work is the expansive black cotton soil obtained from Deba in Gombe State in the North Eastern part of Nigeria. The soil was collected by method of disturbed sampling. The top soil was removed to a depth of about 0.5 m and the soil samples were taken below 0.5 m, sealed in plastic bags and put in sacks. This was done to avoid loss of moisture during transportation. In the laboratory, the soil was pulverized to obtain particles passing sieve through British Standard No. 4 sieve, (4.75 mm aperture). Bagasse ash: The bagasse ash used was obtained from local sugar manufacturing mills in Anchau, Kaduna State. The fibrous residue (after the juice has been extracted) of sugar cane was collected, dried and burnt in the open atmosphere. The ash was collected after complete burning, sealed up and transported to the laboratory. The ash was then passed through British Standard No. 200 sieve (75 µm aperture). The fraction passing sieve No. 200 was collected and mixed with soil-lime mixture in increment of 0, 2, 4, 6 and 8 % by weight of dry soil to obtain the required sample for the tests. Lime: The lime used was a hydrated lime type obtained from National Research Institute for Chemical and Leather Technology (NARICT), Zaria. The lime was added in increment of 0, 2, 4, 6 and 8% by weight of the dry soil.

Methods Index properties and oxide composition The laboratory tests to determine the index properties of the natural soil and soil-limebagasse ash mixtures were conducted in accordance with British Standards BS 1377: (1990). The oxide composition of the materials was determined at the Center for Energy Research and Training (CERT), A. B. U. Zaria, using the method of Energy Dispersive X-Ray Fluorescence (EDXRF). The results are shown in Table 1. Compaction and unconfined compressive strength tests The moisture-density relationship of the soil and the soil-lime-bagasse ash mixture was determined by compaction test in accordance with BS 1377 (1990) and BS 1924 (1990) using the British Standard light (standard Proctor), (BSL),West African standard, (WAS) and British standard heavy, (BSH) compactive efforts. The compactive effort for WAS and BSH consists of the energy derived from 4.5 kg rammer falling through 45cm onto five layers, each receiving 10 and 27 blows, while the BSL consist of energy derived from 2.5 kg rammer falling through 30cm on three layers each receiving 27 blows. The soil-lime-bagasse ash mixture were mixed thoroughly with associate amount of water and left for elapse time of 0, 1, 2, and 3 hours before

Vol. 18 [2013], Bund. B

222

compaction. A minimum of five determinations was conducted within which the maximum dry density and optimum moisture content was obtained. The unconfined compression test was carried out in accordance with BS1377: 1990 Part 7 using the energy of standard Proctor, (BSL) the British heavy (BSH) and the West African standard (WAS) compactive effort. The samples of soil and soil-lime-bagasse ash mixture were prepared by mixing the desired proportions of potable water, soil, lime and bagasse ash. The percentages of lime and bagasse ash ranged from 0 to 8 % by weight of dry soil, respectively. The soil-lime-bagasse ash mixtures were first thoroughly mixed in a tray to obtain a uniform color. The require amount of water determined from moisture-density relationships for soil-limebagasse ash mixtures was added to the dry soil-lime-bagasse ash mixture and left for elapse time of 0, 1, 2, and 3 hours before compaction. The Specimen were cured for 7, 14 and 28 days in the case of the unconfined compression where as the durability assessment of the soil-lime-bagasse ash and the admixture was done by the immersion in water tests for the measurement of resistance to loss in strength. The resistance to loss in strength was determined as the ratio of the UCS of specimen wax cured for 7 days, de-waxed top and bottom and then immersed in water for another 7 days to the UCS of specimen wax-cured for 14 days.

RESULTS AND DISCUSSION Properties of Materials The particle size distribution of the natural soil is shown in Fig. 1, while its index properties are summarized in Table 2. The soil classifies as A-7-6 using the Association of American States Highway and Transport Officials Classification System (AASHTO) and clay of high plasticity (CH) in the Unified Soil Classification System (USCS). The soil has a liquid limit of 60 %, plasticity index of 32 % and linear shrinkage of 20 % respectively. The MDD values are 1.47, 1.55 and 1.83 Mg/m3 for BSL, WAS and BSH compactive efforts respectively. The UCS value of 173, 343 and 633kN/m2 recorded at BSL, WAS and BSH compactive energy level. The values of plasticity index (PI) and linear shrinkage indicates that the soil has a high swelling potential with a critical degree of expansion when classified on the basis of plasticity index and shrinkage limit (Altmeyer, 1955; Raman, 1967). The oxide compositions of the lime and bagasse ash are summarized in Table 1.

Vol. 18 [2013], Bund. B

223

100

Percentage Passing (%)

90 80 70 60 50 40 30 20 10 0 0.001

0.01

0.1

1

Particle Size (mm)

Figure 1: particle size distribution of Natural Black Cotton Soil

Table 1: Oxide Composition of Lime and Bagasse Ash Concentration, % Oxide CaO SiO2 Al2O3 Fe2O3 Mn2O3 K2O TiO2

Lime

Bagasse ash

43.93 37.71 11.67 0.17 0.11 0.18 0.93

2.25 63.47 16..55 1.57 0.26 3.00 1.27

Table 2: Index Properties of Natural Soil Property

Quantity

Natural moisture content % Liquid Limit, % Plastic Limit, % Plasticity Index, % Linear Shrinkage, % AASHTO classification USCS classification Specific Gravity Maximum Dry Density, (Mg/m3) British Standard Light West Africa Standard British Standard Heavy

5.1 60 22 38 20 A-7-6 CH 2.35 1.47 1.55 1.83

10

Vol. 18 [2013], Bund. B Optimum Moisture Content, (%) British Standard Light West Africa Standard British Standard Heavy Unconfined Compressive Strength, (kN/m2) British Standard Light West Africa Standard British Standard Heavy

224

21.5 18.7 13.9 173 343 633

Effect of compactive efforts and elapse time on unconfined compressive strength The results of the unconfined compressive strength of soil - lime mixture treated with bagasse ash content compacted at the energy levels of BSL, WAS and BSH and cured for 7, 14 and 28 days are shows that for soil treated with 6% lime and 8% bagasse ash, strength increased from about 410, 680 and 1060 kN/m2 at 7 days to 540, 850 and 1330 kN/m2 at 28 days curing for BSL WAS and BSH compactive energy respectively. The results obtained indicates that UCS values increased with increase compactive energy, with BSH giving the peak value of UCS for all lime and bagasse ash treatment, curing periods and elapse time. The effect of delay between mixing and compaction (elapse time) is shown in Figures 2 (a)(c); 3 (a)-(c) and 4 (a)-(c) for BSL, WAS and BSH compactive efforts for 7, 14 and 28 day curing periods. The UCS generally decreased with elapse time. This was expected and is consistent with other reports on lime stabilization (Mitchell and Hooper, 1961). There was a decrease in UCS from a value of 426, 510 and 585 kN/m2 at 6% lime and 8% bagasse ash and BSL compactive effort to 370, 375 and 408 kN/m2 after 3 hours elapse time for 7 days curing period. At the energy level of West Africa standard, the UCS values decreased from a peak value of 680, 750 and 850 kN/m2 at 6% lime-8% bagasse ash content at 7, 14 and 28 days to a value of 490, 600 and 610 kN/m2 after three hours elapse time. At British heavy energy level, maximum UCS value were 1060, 1210 and 1330 kN/m2 at 6% lime-8% bagasse ash at 7, 14 and 28 days. These however decrease with elapse time to 780 kN/m2, 960 kN/m2 and 930 kN/m2 after three hours elapse time. There was an average of about 22 -29% decrease in strength for an elapse time of 3 hours. The reduction in strength may be attributed to the destruction of the cementation bond formed during the soil-lime-bagasse ash reaction over the period of time between mixing and compaction. The destruction of this matrix during compaction results in reduction of the soil density and consequently, reduction in strength of the compacted soil.

Vol. V 18 [2013], Bund.. B

225 00%BA,0%L 00%BA,2%L 00%BA,4%L 00%BA,6%L 00%BA,8%L 22%BA,0%L 22%BA,2%L 22%BA,4%L 22%BA,6%L 22%BA,8%L 44%BA,0%L 44%BA,2%L 44%BA,4%L 44%BA,6%L 44%BA,8%L 66%BA,0%L 66%BA,2%L 66%BA,4%L 66%BA,6%L 66%BA,8%L 88%BA,0%L 88%BA,2%L 88%BA,4%L 88%BA,6%L 88%BA,8%L

2) p g , (kN/m ( Uconfined Compressive strength,

600 500 400 300 200 100 0 0

1

2

3

Ela apse Time, ((Hrs)

Figu ure 2(a): Vaariation of UCS U with Elaapse time at 7 days curinng (BSL Com mpaction)

Uconfined Compressive strength, (kN/m (kN/ 2)

700 600 500 400 300 200 100 0 0

1

2

Elap pse Time, (H Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L

Figu ure 2(b): Variation of UC CS with Elap pse time at 114 days curinng (BSL om mpaction)

Vol. V 18 [2013], Bund.. B

226

Uconfined Compressive strength, (kN/m2)

700 0 600 0 500 0 400 0 300 0 200 0 100 0 0 0

1

2

3

E Elapse Timee, (Hrs)

0% %BA,0%L 0% %BA,2%L 0% %BA,4%L 0% %BA,6%L 0% %BA,8%L 2% %BA,0%L 2% %BA,2%L 2% %BA,4%L 2% %BA,6%L 2% %BA,8%L 4% %BA,0%L 4% %BA,2%L 4% %BA,4%L 4% %BA,6%L 4% %BA,8%L 6% %BA,0%L 6% %BA,2%L 6% %BA,4%L 6% %BA,6%L 6% %BA,8%L 8% %BA,0%L 8% %BA,2%L 8% %BA,4%L 8% %BA,6%L

Unconfined Compressive Strength (kN/m2)

Fig gure 2(c): Variation of UCS U with Elaapse time at 28 days curring (BSL coompaction)

700 600 500 400 300 200 100 0 0

1

2 Elapse Time T (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L 8%BA,6%L 8%BA,8%L

Fig gure 3(a): Vaariation of UCS U with Elaapse time at 7 days curinng (WAS Coompaction)

Unconfined Compressive Strength (kN/m2)

Vol. 18 [2013], Bund. B

227

800 700 600 500 400 300 200 100 0 0

1

2

3

Elapse Time (Hrs)

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L 8%BA,6%L 8%BA,8%L

Figure 3(b): Variation of UCS with Elapse time at 14 days curing (WAS Compaction)

Unconfined Compressive Strength (kN/m2)

900 800 700 600 500 400 300 200 100 0 0

1

2 Elapse Time (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L

Figure 3(c): Variation of UCS with Elapse time at 28 days curing (WAS ompaction)

Vol. 18 [2013], Bund. B

228

Unconfined Compressive Strength (kN/m2)

1600 1400 1200 1000 800 600 400 200 0 0

1 2 Elapse Time (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L

Unconfined Compressive Strenght (kN/m2)

Figure 4(a): Variation of UCS with Elapse time at 7 days curing (BSH Compaction)

1400 1200 1000 800 600 400 200 0 0

1

2

Elapse Time (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L 8%BA,6%L 8%BA,8%L

Figure 4(b): Variation of UCS with Elapse time at 14 days curing (BSH ompaction)

Unconfined Compressive Strength (kN/m2)

Vol. 18 [2013], Bund. B

229

1400 1200 1000 800 600 400 200 0 0

1

2

Elapse Time (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L 8%BA,6%L 8%BA,8%L

Figure 4(c): Variation of UCS with Elapse time at 28 days curing (BSH ompaction)

Durability (Resistance to loss in strength) A stabilized soil is usually accepted on the basis of meeting strength and durability requirements. The durability assessment is based on the ratio of the UCS of specimen wax cured for seven days de-waxed top and bottom and immerse in water for another seven days and specimen waxed cure for 14 days. Conventionally, an allowable 20% loss in strength is recommended for a specimen cured for seven days and immersed in water for four days (Ola, 1974; Osinubi, 1998a; 1999a). Durability assessment of the soil-lime-bagasse ash mix showed a decline in the resistance to loss in strength of the mixes with elapse time for all compactive efforts as shown in Figures 5 (a)-(c). At zero elapse time, the resistance to loss in strength is 14.89, 23.12 and 33.90 % respectively for BSL, WAS and BSH compactive efforts. These further reduced with elapse time to 4.95, 11.87 and 20.08 % after 3 hours elapse time. These values translate to about 96 to 98 % loss in strength. The resistance to loss in strength values of tested specimens fell far short of the acceptable conventional 80 % accepted as minimum by Ola (1974).

Vol. 18 [2013], Bund. B

230

35 30 25 20 15 10 5 0 0

1

2

3

Elapse Timen (Hrs)

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L 8%BA,6%L

Figure 5(a): Variation of RSL with Elapse time (BSL Compaction)

30 Resistance to Loss in Strength (kN/m2)

Resistance to Loss in Strength (kN/m2)

40

25 20 15 10 5 0 0

1

2 Elapse Timen (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L

Figure 5(b): Variation of RSL with Elapse time (WAS Compaction)

Vol. 18 [2013], Bund. B

231

Resistance to Loss in Strength (kN/m2)

40 35 30 25 20 15 10 5 0 0

1

2 Elapse Timen (Hrs)

3

0%BA,0%L 0%BA,2%L 0%BA,4%L 0%BA,6%L 0%BA,8%L 2%BA,0%L 2%BA,2%L 2%BA,4%L 2%BA,6%L 2%BA,8%L 4%BA,0%L 4%BA,2%L 4%BA,4%L 4%BA,6%L 4%BA,8%L 6%BA,0%L 6%BA,2%L 6%BA,4%L 6%BA,6%L 6%BA,8%L 8%BA,0%L 8%BA,2%L 8%BA,4%L 8%BA,6%L 8%BA,8%L

Figure 5(c): Variation of RSL with Elapse time (BSH Compaction)

CONCLUSIONS This research was conducted to investigate the effect of compactive efforts and elapse time on the strength and durability of black cotton soil-lime-bagasse ash mixes. The soil was treated with lime and bagasse ash in stepped concentration of 0, 2, 4, 6 and 8% by dry weight of the soil. The results obtain that:  The recommended peak values of UCS were obtained at 6 % lime/ 8 % bagasse ash treatment regardless of compactive effort used.  UCS of specimens generally increased at higher compactive efforts and curing.  UCS of specimens generally decreased with elapse time for all compactive efforts, curing age and lime-bagasse ash treatment.  There was an average of about 22 -29 % decrease in strength for an elapse time of 3 hours for the entire specimen tested.  Although, there is no established strength criterion for soil-lime/bagasse ash mix, but using the 7 day UCS value of 1034.25kN/m2 normally utilized as criterion for adequate lime stabilization, it is observed that sample stabilized with 6% lime/8%bagasse ash did not achieve the required strength. The strength at 28days however showed that the strength development of lime/bagasse ash is a slow process and a longer period is required to attain the specified strength.

Vol. 18 [2013], Bund. B

232

 Durability assessment of the soil-lime-bagasse ash mix showed a decline in the resistance to loss in strength of the mixes with elapse time for all compactive efforts. The resistance to loss in strength values of tested specimens fell far short of the acceptable conventional 80 %, as reported by Ola (1974).

REFERENCES 1. Altmeyer, W. T. (1955) “Discussion of Engineering Properties of Expansive Clays. Proc. of Am. Soc. of Civil Eng. Vol. 81 (separate No. 658), pp. 17-19. 2. Chen, F. H. (1988) Foundation on expansive soils. 2nd ed., Elsevier, New York. 3. Hausmann, M. N. (1990) Engineering principles of ground modification. McGraw- Hill, New York. 4. Mitchell, K. J. and Hooper, D. R. (1961) “Influence of time between mixing and Compaction of a lime stabilized expansive clay.” Highway Research Board Bulletin, 304 Washington D.C. pp.14-31. 5. Mohammedbhai, G. T. G and Baguant, B. K. (1985) “Possibility of using Bagasse ash and other Furnance Residue as Partial Substitute for Cement in Mauritius.” Revue Agricole et Sucrlere de l’jje Maurice. 64 (3) 6. Nelson, D. J. and Miller, J. D. (1992) Expansive soils: Problems and practice in foundation and pavement engineering, Wiley, New York. 7. Nicholson, P. G., Kashyap, V. and Fuji, C. F. (1994) “Lime and fly ash admixture improve- ment of tropical Hawaiian soil.” Transport Research Record. No. 1440. National Academy press, Washington, D.C. 8. Ola, S.A. (1974) “Need for estimated cement requirements for stabilizing lateritic soil.” Journal of Transportation Engineering, ASCE, Vol. 17, No. 8. pp. 379-388. 9. Osinubi, K. J. (1995) “Lime modification of black cotton soil.” Spectrum Journal Vol. 2 Nos. 1 and 2, pp.112-122. 10. Osinubi, K. J. and Katte, V.Y. (1997) “Effect of elapse time after mixing on grain size and plasticity characteristic. I: Soil-lime mixes.” The Nigerian Society of Engineers Technical Transactions, Vol. 32, No. 4, pp. 65 - 77. 11. Osinubi, K. J. (1998a) “Influence of compactive efforts and compaction delays on limetreated soil.” Journal of Transportation Engineering, ASCE, Vol. 124, No. 2, pp. 149 155. 12. Osinubi, K. J. (1998b) “Influence of compaction delay on the properties of cementstabilised lateritic soil.” Journal of Engineering Research, Vol. JER-6, No. 1, pp.13 - 26. 13. Osinubi, K. J. and Medubi, A. (1998) “Evaluation of cement and phosphatic waste admixture on tropical black clay road foundation.” Proc. Of the 4th Int. Conf. on Sructural Engineering Analysis and Modelling (SEAM 4) Accra, Vol. 2, pp. 297-307. 14. Osinubi, K. J. (1999a) “Evaluation of admixture stabilization of Nigerian black cotton soil.” The Nigerian Society of Engineers Technical Transactions, Vol. 34, No. 3, pp. 88 - 96.

Vol. 18 [2013], Bund. B

233

15. Osinubi, K. J. (1999b) “Influence of compaction delay on the properties of limestabilised lateritic soil.” Journal of Engineering Research, Vol. JER-7, Nos. 1 &2, pp. 129 – 142. 16. Osinubi, K.J. and Katte, V.Y. (1999) “Effect of elapsed time after mixing on grain size and plasticity characteristic. II: Soil-cement mixes.” The Nigerian Society of Engineers Technical Transactions, Vol. 34, No. 3, pp.38 - 46. 17. Osinubi, K. J. and Alhaji. M. M. (2005) “Potentials of bagasse ash as a pozzolana.” Proceedings of the 4th Nigerian Materials Congress “NIMACON 2005”, Zaria, Nigeria, 17 – 19 November, pp. 41 -45. 18. Osinubi, K. J. and Stephen, T. A. (2005) “Economic utilization of an agro-industrail waste-bagasse ash.” Proc. of The Nigerian Material Congress 2005 (NIMACON 2005) 17-19 Nov., Zaria, Nigeria, pp. 36-40. 19. Osinubi, K. J. and Stephen, T. A. (2006a) “Effect of bagasse ash content on particle size distribution and plasticity characteristics of black cotton soil.” Proceedings of the 5th Nigerian Materials Congress “NIMACON 2006”, Abuja, Nigeria, 17-19 November. pp. 214 - 220. 20. Osinubi, K. J. and Stephen, A. T. (2006b) “Effect of curing period on bagasse ash stabilized black cotton soil.” Proc. of Bi-monthly Meetings/Workshopsorganized by the Zaria Chapter of Materials Society of Nigeria, pp. 1 - 9. 21. Osinubi, K. J. and Nwaiwu, C. M. O. (2006) “Compaction delay effects on properties of lime treated soil” Journal of material in civil engineering, Vol 18, No. 12. Pp 150-158. 22. Osinubi, K.J., Ijimdiya, T. S. and Nmadu, I. (2008) “Lime stabilization of black cotton soil using bagasse ash as admixture.” Book of Abstracts of the 2nd International Conference on Engineering Research & Development: Innovations (ICER&D 2008), Benin City, Nigeria, 15-17 April. Technical Session 9B – Construction and Structures, Paper ICERD08058, pp. 217 23. Raman V. (1967) “Identification of Expansive Soils from the Plasticity Index and Shrinkage Index Data, Indian Eng., Calcutta Vol 11, No. 1. pp. 17-22.

© 2013, EJGE