Effect of secondary porosity propagation to the engineering properties of Kubang Pasu tropical weathered sandstone

The propagation of secondary porosity as the result from weathering process created very complex properties of rock structure, both dynamic and engineering properties. In the tropical climate, which has unique weathering process has produced a complex structure of rock which includes the arrangement of pore structure, mineral compositions, grains size and others. The process of weathering involves the wetting and drying, which take place with the presence of water inside the rock microstructure, then further created the numbers of micro-pore which contributing to weakens the rock structure. This study was focused on to analyze the effect of secondary porosity variation due to the weathering of rock to the tropical weathered sandstone that was collected from Kubang Pasu formation located in northern peninsular Malaysia. The block of the rock sample was cored into cylindrical shape with size of 50 mm diameter and 100 mm length using static coring machine in the laboratory. Total 45 numbers of cylindrical samples were cored, at three different grades of weathering (WG) comprises of WG II, WG III and WG IV. The saturation & caliper method were used to determine the porosity percentage, and P-wave velocity by adopting ultrasonic pulse velocity test (UPV). Further investigation was made to evaluate the deformation characteristics of weathered sandstone under the uniaxial compressive stress as well as the crack pattern depending on its weathering grades. It can be concluded that the porosity is the main controlling factor that effecting the other properties of rock.