Effect of GGBFS and lime binders on the engineering properties of clay

Abstract

Although lime is one of the most suitable binders in soil improvement projects, the associated environmental impact and some accompanying mechanical deficiencies should not be ignored. Partial substitution of lime with other binders is one of the ways of reducing the associated harm and improving the engineering properties of lime. This study investigated the effect of the partial substitution of lime with ground granulated blast furnace slag (GGBFS) on the strength and mechanical properties of lime stabilised clay by performing a total of 246 volumetric shrinkage strain (VSS), unconfined compressive strength (UCS) and ring shear (RS) tests. The VSS results demonstrated that the addition of GGBFS to lime is very effective in reducing the volumetric shrinkage of lime stabilised clay, and that the reduction in volumetric shrinkage behaviour is linearly related to curing period. The UCS results revealed that the partial replacement of lime with GGBFS led to significantly higher compressive strength for all ageing periods. The ring shear results also demonstrated that the partial replacement of lime with GGBFS led to a greater shear strength. Moreover, microstructural studies were performed to better understand the reactions of the mixtures. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) carried on selected specimens revealed that the addition of GGBFS in a lime stabilised clay results in production of the cementitious products in a faster rate. X-ray powder diffraction (XRD) test results revealed that the main hydration products are cementitious products such as calcium silicate hydrates (CSH), calcium aluminates (CAH).