A laboratory study of climate change and subgrade strength of a lateritic soil in a tropical environment

In the tropical environment, most of the road network is founded on lateritic subgrade soils. Climate change in certain parts of the tropics is projected to lead to increasing temperatures and a reduction in annual rainfall leading to a decrease in the water content of the subgrade. This paper seeks to mimic part of the water content changes projected to occur in a subgrade in order to help understand the subgrade response in terms of the CBR. A lateritic soil of subgrade quality was collected and prepared for laboratory testing. After characterization, a number of samples were compacted at the optimum water content to various levels of compaction. One set was subjected to different degrees of drying while the second set was subjected to different degrees of wetting, thus creating samples with water content ratios ranging from as low as 0.2 to a maximum of about 1.2 of the optimum water content. After the moisture conditioning, each sample was subjected to the CBR test and the matric suction was determined. The results of the CBR changes are discussed and interpreted to mimic the water content changes in a subgrade in a tropical environment for climate situations varying from extreme dryness to excessive rainfall.