Geotechnical Characterization of Selected Soil for use as Sub base Materials for Low Volume Road Construction: A Case Study of Bilate Quarry Site, Southern Ethiopia

This article presents a laboratory investigation on a soil sample from Bilate quarry site in relation to its use as sub base materials in low volume road connecting Keranso kebele to Langano kebele of Misrak Badwacho woreda of southern Ethiopia. Engineering tests such as, sieve size analyses, atterberg limits, compaction and California Bearing Ratio were carried out on sample collected from the quarry site. All the analysis was carried out in line with the ASTM testing procedures. The results obtained showed that the soil investigated contains 8.96% fine, 43.71% sand 47.33gravel. The result of atterberg limits analysis showed that the liquid limits is 46.57%, plastic limit is 35.74% and index of plasticity is 10.83%. From modified compaction test it is found that maximum dry density/MDD/ of the soil is 1.74g/cm3 and optimum moisture content/OMC/ is 19.16%. California bearing ratio/CBR/ value at 95% MDD is found to be 25.5% and it is less than minimum standard CBR (30%) value for sub base material. Thus the soil from quarry site does not fulfill the strength criteria for sub base material in low volume roads construction.