Stabilization of Clayey Soil Using Lime and Lime with Prosopis Juliflora Fibers in Jimma Town

Abstract

The properties of clayey soils can be problematic due to the damage it can bring to civil engineering structures such as roads, buildings and others infrastructures. This is because the clayey soil swell when contact water and shrink when it dry out. This type of soil occurs in many countries in the world, Ethiopia is one of those countries. The problematic nature of these soils can be improved by chemical stabilization techniques using cement, lime and fly ash. However, these chemicals are too expensive to develop countries such as Ethiopia. Therefore, it is important to discover low cost and available materials to utilize as soil stabilizer. The general objective of this research was to investigate the effects of lime alone and mixture of lime with Prosopis Juliflora fibers on stabilization of clayey soils in Jimma town .In this study, was conducted by using experimental method. Two clayey soil samples were taken from the study area by observation and free swell index tests at a depth of 1.50 m to remove organic matter. Prosopis Juliflora fibers was extracted from the inner barks of the prosopis juliflora trees. In addition, hydrated Lime was obtained from Senkele Lime Factory. Laboratory tests were carried out for moisture content, sieve analysis, specific gravity, atterberg limits, linear shrinkage, compaction tests, CBR and CBR swell tests. The laboratory test results, was compared with ERA, AASHTO and ASTM, specifications. The laboratory test results, indicated that the natural sub-grade soil of the selected area has a low load bearing capacity and unsuitable for use as sub-grade material. Hence, to improve the engineering properties of the soil a stabilization techniques was used by adding different percentages of lime 4%, 6% and 8% alone and mixture of 5% lime with different percentages of Prosopis juliflora fibers 0.5%, 1%, 1.5% and 2%. From the laboratory test results, it was inferred that the optimum content of lime and lime with prosopis juliflora fibers required to achieve superior geotechnical properties in clayey soil was found to be 6% lime alone and mixture of 5% lime with 1.5% fibers. At this optimum combination, the CBR of sample-1 increased from 1.21% to 8.93% and 1.21% to 8.28% and the CBR of sample-2 increased from 1.96% to 9.93% and 1.96% to9.26% with the addition of 6% lime alone and 5% lime with 1.5% fibers, respectively. Furthermore, the result shows that the improvement of 6% of lime alone and 5% lime with 1.5% fibers are more likely same improvement. Therefore, 1% lime can be partially replaced by 1.5% fibers to reduce the cost of the lime. The results was compared with standard specifications by compared the value obtained from the laboratory tests with the required value on the standard specifications .Hence, the obtained value from the test results fulfilled the required value on the standard specifications. Therefore, it is recommended to use 6% lime alone or mixture of 5% lime with 1.5% prosopis juliflora fiber