Expansive Soil Stabilization by Sugare Cane Molasses
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Date
2016-04
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Addis Ababa University
Abstract
Expansive soils are active clays that pose problem to civil engineering structures. This is caused by structural and volume instability in the soil mass due to swelling and shrinkage characteristics triggered by moisture variation. These soils are found in widespread areas in the world. Several researches have been done and various methods and techniques have been proposed and developed for stabilization of expansive soils to improve engineering properties. During construction, the removal of expansive soils and replacement with suitable fill material is an appropriate method in areas where abundant suitable fill materials are available nearby. However, at places of limited suitable fill material within economical distance and if large thickness of poor sub-grade soil to be replaced occurs, the method is not suitable. The most commonly used technique is chemical stabilization with cement and lime. These chemicals are most effective when used on site with very controlled moisture of hydration and site specific techniques. Other manufactured inorganic and organic compounds are used worldwide but most of them are not economically viable. Since most of them are import commodities they are very expensive. This is especially true for developing countries like Ethiopia.
The rising cost of traditional stabilizing agents and the need for economical utilization of industrial and agricultural wastes for valuable engineering purposes has driven an investigation into the stabilizing potential of molasses (a byproduct of sugar industry) in expansive clay soils.
The necessary laboratory tests, index tests, strength testes, swelling tests are incorporated for the natural as well as the stabilized soil. Chemical and physical testes to characterize the stabilizer molasses has also been carried out.
Analyses of the results show that slight improvement on the geotechnical properties of Molasses stabilized soil. Molasses reduces plasticity index, CEC, soil PH, swelling potentials and swelling pressure and OMC and increased MDD, CBR, UCS values as molasses content is increased up to certain percentage. On the other hand if the Molasses is increased beyond certain percentage the reverse properties are observed. Curing has an insignificant effect on the geotechnical properties of molasses stabilized soil. From this research work it was found out that molasses stabilized soil does not meet the minimum requirement of ERA pavement manual specification for use as a sub-grade material in road construction.
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Geotechnical Engineering