Strength and compressibility characteristics of cement treated laterite soil under saturated and unsaturated conditions

Abstract

Laterite soil is known as firm soil and is commonly used as a potential subgrade material for pavements. However, due to dry and rainy seasons caused by climate change, road infrastructure in Malaysia is affected massively, which weakens their natural bond. Hence, it is important to comprehensively emphasise the soil shear strength and compressibility to design a longer lifespan for the pavement subgrade. Therefore, soil stabilisation is a method for enhancing on-site materials to create a competent and stable subgrade. From previous researchers, cement is widely used as a stabiliser for building construction. Thus, the main objective of this research is to investigate the capability of cement as a stabiliser in laterite soil stabilisation. Therefore, several laboratory analyses had been carried out according to the mixture formulation between different cement percentages with laterite soil. The cement type used in this research was Ordinary Portland Cement (OPC) CEM I 42.5N. From the unconfined compression test (UCT) results, it is indicated that 6% cement-treated laterite soil at 7 days of curing is capable of achieving the stabilised soil required strength (800 kPa) of low-volume road by the Public Work Department of Malaysia for 1.0 million ESAL (Equivalent Single Axle Load). Moreover, the UCT results also implied that the cement addition improved the soil strength, which is also evidenced by the soil microstructure images from the microstructural analysis. The compressibility tests proved that laterite soil experienced high compressibility in fully saturated condition, while the compressibility was significantly reduced in partially saturated condition. Hence, the unsaturated oedometer tests showed a significant reduction in soil compressibility at a higher suction level (drying condition) compared to that of lower suction (wetting condition). In conclusion, this research output provides fundamental knowledge by proving the capability of cement to be applied as a stabiliser for the subgrade material in the design guidelines of road construction in Malaysia.