Laboratory Investigation of the Physico-Mechanical Properties of Coral Limestone of Vipingo Area in Kenya’s Coastal Region

Abstract

This study investigates physical and mechanical characteristics of the Pleistocene coral limestone of Kenya’s coastal plain by laboratory experiments based on ASTM standards. The experiments have done include uniaxial compression test, indirect tensile test, ultrasonic pulse velocity (UPV) test, saturation porosity for porosity and direct shear test. Engineering properties of brittleness, Schmidt’s rebound number, fracture index and drillability index are calculated from empirical equations based on the tensile strength and uniaxial compressive strength available in published literature. The various moduli are also calculated from equations based on the P-wave and Swave velocities from UPV test. The average values of the investigated physical properties include bulk density (2199kg/m 3 ), porosity (8.47%). The average investigated mechanical properties values include uniaxial compressive strength (16.41MPa), tensile strength (1.61MPa), Elastic modulus(31.62GPa), cohesion(133.33kPa) and friction angle (410). The P-wave and S-wave velocities are 4797m/s and 2288m/s respectively. The results presented in this work highlight the influence of rock porosity as an inherent structural feature that affects intact rock properties. The results are discussed with a focus on the variation of properties with porosity, with the conclusion that empirical relationships developed for porous rock should include porosity as a parameter which contributes to variations in rock properties. This paper presents the first published geomechanical data of coral limestone from the reef coral rock formation making up Kenya’s coastline.