A Case Study of the Residual and Saprolitic Soils of Mauritius

A few studies on residual and saprolitic soils of volcanic origin similar to those encountered in Mauritius have been conducted so far. Past research projects on these soils have shown a divergence in the bonding characteristics where very weak bonding was present in a sampled saprolitic soil and no bonding was seen in a sampled residual soil. In order to establish a framework for these soils, it is important to conduct in-depth testing for soils from other regions of Mauritius. Two sites were identified around Cote D’Or region (around 5 kms apart) where rapid construction development is ongoing. Block samples from depths of 1 m to 4 m were retrieved and analysed under scanning electron microscope to determine the micro-grains patterns and impact on the physical properties. Consolidated undrained tests were also carried out on soil samples in both undisturbed and remoulded states. It has been observed that these two sites have more pronounced bonding characteristics even at high confining pressures, compared to previous research carried out on other soils in Mauritius where no bonding and very weak bonding were reported. The remoulded soils are found to behave as normally consolidated soils, and cohesion in undisturbed materials is found to decrease with depth. This research adds knowledge to the bonding characteristics of residual and saprolitic soils where materials can vary from unbonded to highly bonded.