Evaluation Of The Suitability Of Laterite Soil As Road Construction Material: A Case Study In Jimma Town.

Abstract

In tropical areas, where chemical weathering is often intense, the availability of suitable rock as a source of crushed aggregate may be limited. Considerable savings can be achieved by using local materials such as laterite soils, even though these may appear to be of marginal quality when judged by certain specification using conventional testing procedures.For this Independent project study samples were collected from one of the heaps of laterite brought from the stock at Jimma town around 4+900 Km on Foristale (Seto Semero Kebele) The samples were subjected to the following laboratory tests; Particle (grain) size analysis, Atterberg limit test, Compaction test, California bearing ratio (CBR) test and Specific gravity test. The effect of temperature and mixing time in the engineering properties of the samples were taken in to account while analyzing the laboratory results. The AASHTO system classifies the samples as A-1-b, A-2-5 and A-2-7 that are rated as subgrade material of Excellent to Good. However, the USC system categories the samples under MH group which is poor for use as construction material and having high compressible engineering property. Based on the evaluations, and comparing the results with ERA standard specification, the laterite soils of Jimma do not fulfill both the sub base and base course criterion. However, this material can be used as road embankment, subgrade capping and even as filter construction Material.