Correlation of Mineralogical and Geotechnical Properties of Laterite Soils of Coastal Karnataka, India

Abstract

Laterites are the main underlying soil structure in coastal Karnataka, and its detailed study of mineralogy and engineering properties is of utmost importance since any engineering structure like buildings, pavements, railways, dams, etc. need to be stable and durable through all the seasons. Civil engineering gains importance here, as there is huge scope for constructional activities. There is a requisite for understanding the laterites in a much more detailed manner so that the constructed entities remain intact, durable, and also easily maintained. Even the existing structures like roadways are damaged due to the water-absorbing properties of underlying lateritic soil. In this study, the coastal region of Karnataka consists of 3 districts-Uttara Kannada, Udupi, and Dakshina Kannada. The disturbed soil samples have been collected from a depth of 2.5 m from the ground level of the soil stratum for X-Ray Diffraction analysis. It has been sieved through 75 microns sieve size before the sample was given for X-Ray Diffraction testing. These testing results were analyzed in Origin software. Corundum, Anatase, Magnetite, Quartz, and Hematite were the major minerals. Later the quantity of mineral contents obtained from the analysis was correlated with the geotechnical properties like specific gravity, Atterberg limits, etc. using Microsoft Excel, and graphs were plotted. It’s observed that specific gravity increases with all the mineral contents. Soaked California Bearing Ratio values decrease with all the mineral contents, and Unsoaked California Bearing Ratio values increase with all the minerals except Corundum. This result shows that the laterite soil possesses lesser fine grains, which implies its higher frictional angle and lesser cohesion values. Shear parameters appear to be generally higher for undisturbed fine-grained laterite soils and are found to depend to a large extent on the type of parent rock, degree of saturation, and degree of weathering. Hence, this research will help in understanding the laterites more comprehensively and suggesting solutions will be possible from the obtained results.