Engineering properties of common subgrade soils below pavement structures in Kenya

Abstract

This paper reports findings of laboratory testing of common sub-grade soils in pavement structures in Kenya. The materials were collected from different parts of the country. The results are intended to form a database for use by practicing engineers and researchers in the field of pavement engineering. The investigated materials include the expansive black soils, silty clayey soils, sandy loamy clayey soils and lateritic gravels. In addition the properties of lime improved gravels are reported. For the fine-grained soils the plasticity index was found to be linearly proportional to the liquid limit. In all the investigated soils the optimum moisture content was found to be inversely proportional to the maximum dry density. The increase in the strength of lime improved materials was found to increase with lime content at a diminishing effect