Geotechnical Properties of Tropical (Lateritic) Soils and Their Implications for Road Construction: A Case Study from Bahir-Dar, Ethiopia

Abstract

The research demonstrates the geotechnical properties of tropical soils and their implications for road construction. A series of standardized geotechnical and geochemical laboratory tests on lateritic soils of Bahir-Dar (Ethiopia) were conducted. Soil samples at depths of 0.6m and 1.5m were collected from five sites. The silica to sesquioxide ratio indicated that soils are lateritic. The findings show invariable particle-size distribution and Natural Moisture Content range between 4.53 to 12.2%. Average Maximum Dry Density and Optimum Moisture Content were 1.563 and 20.58 respectively. The specific gravity ranges from 1.95 to 3.09. The LL, PL, and PI range from 42 to 86.3%, 28.38 to 38.4%, and 13.12 to 49.7% respectively. The unsoaked CBR and corresponding soaked CBR values range from 4.86 to 14.36% and 1.22 to 3.88% respectively at 65 blows of the modified proctor. The results evaluated suitability of soils according to the Ethiopian Roads Authority standards and implicated that partially Test Pits-C, D & E soils satisfy to be a sub-grade or embankment material.