Improvement of the performance of micaceous laterites and expansive soils using Geogrit for low volume traffic roads.

Abstract

Building road infrastructure is a crucial aspect of economic development providing vital connectivity and facilitating trade and transportation. However the cost of road construction and maintenance remains a significant concern for governments and project stakeholders. This research project aims at addressing this problem by investigating the application of the Geogrit system as a cost-efficient and environmentally friendly method for stabilizing micaceous laterites and expansive soils. Expansive soils are characterized by very low bearing capacity, high compressibility, low permeability and high volumetric changes due to moisture conditions. On the other hand micaceous laterites are characterized by low strength, high compressibility and low compactibility. Geogrit contains two components which are commercially available namely BP2G and BP3G. BP2G hardens the soil by stabilization and BP3G acts as a surface sealant. In this research, laboratory tests were carried out on the micaceous laterites and expansive clay soils. The expansive soil sample was classified as low plasticity clays A-6(7) with 7% group index (GI) in accordance to the AASHTO soil classification system. The micaceous laterites were classified as high plasticity clays A-7-6(4) with 4% group index (GI) in accordance to the AASHTO soil classification system. The test soils were stabilized using Geogrit (BP2G) in variations of 0, 2, 4, 6 and 8%. Laboratory tests that included Atterberg limits tests, Proctor tests and California Bearing Ratio test were carried out on the samples. Results obtained from laboratory experiments were analyzed and regression analysis was used to obtain the optimum amount of Geogrit needed for stabilization. Limiting values from the Ministry of Works and Transport Road design manual were used for the Plasticity index and California Bearing ratio. The optimum dosage for the application of the Geogrit was found to be 2% and the one for the Expansive clay soils was 4%. Test results confirm that the engineering properties of the micaceous laterites and the expansive clay soils are improved with the stabilisation using the Geogrit.