Stabilization of Expansive Clay Soil With Sugar Cane Molasess and Cement
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Date
2015-05
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Addis Ababa University
Abstract
Soil stabilization with the application of Portland cement is one of the most popular methods of soil stabilization. Research showed that molasses can modify properties of expansive soil. Former research has proved that sugar containing molasses improves the quality of reaction between cement and aggregate. Molasses is a local material easily obtained from sugar factories and cheaper than cement. Therefore, a research must be carried on to explore the effect of molasses addition to soil stabilization with Ordinary Portland cement on geotechnical properties.
Research was done on expansive clay soil sample from Modjo-Ejere Road, with addition of molasses alone, cement alone, and combination of cement and molasses by varying content of stabilizers in steeped concentration of 0, 4, 8 and 12% each by dry weight of the soil, was used to treat the soil. Furthermore, the sample soil was treated with combination of cement and molasses by keeping 4% molasses constant and varying cement content to 4, 8 and 12% by dry weight of the soil .i.e. at 1:1, 2:1 and 3:1 cement to molasses ratio. For the analysis of the effect of the stabilizer on soil, comparison was made on geotechnical properties of the native soil and stabilized soil. The comparison includes by carrying out: pH test, compaction test, Atterberg’s limit test, linear shrinkage test, California Bearing Ration (CBR) test, Unconfined Compressive Strength (UCS) test and swelling test on both the native soil and stabilized soil.
Sample soils with molasses application had a relatively higher strength, lower PI (plasticity index) and swelling potentials than those of the native soil. The addition of cement on the sample soil gave significant improvement in strength, eliminated swelling properties and were more effective in improving properties of the natural soil than molasses. However, shrinkage cracks were observed during shrinkage tests and stress-strain curve of the UCS test showed that the soil stabilized with cement had brittle nature. Molasses application on soil-cement mixture gave higher strength, lower PI and negligible swelling potential than those of cement stabilized or molasses stabilized soils.
Molasses application improves soil-cement reaction with water and cause larger size grains than cement /molasses treated soils. Application of molasses on soil-cement mixture has been proven to increases soil strength, to eliminate shrinkage cracks and to reduce brittleness nature of cement stabilized soils. Addition of 4% molasses to 4% cement increased CBR value of 1% of the native soil to 64%, reduced 53% PI value of the native soil to 19%, and reduced 10.4% CBR swell value of the native soil to negligible values. Therefore; soil stabilized with 4% molasses and 4% cement combination satisfied all specification requirements for stabilized sub-grade soil and selected as optimum content of stabilizer for sub-grade soils.
Key Words: Cement, Expansive Clay Soil, Modjo-Ejere, Sugar Cane Molasses, Soil Modification, Soil Stabilization.
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Keywords
Cement; Expansive Clay Soil; Modjo-Ejere; Sugar Cane Molasses; Soil Modification; Soil Stabilization