Evaluation of compressive strength and chloride permeability of cement-based materials with high-volume compound mineral admixtures

Ground granulated blast furnace slag (GGBFS) is well known as the capable of improving the performance of cement-based materials, but few studies focus on the impact of its large dosage on concrete containing basalt powder. In this study, the compressive strength and chloride permeability of cement-based materials with compound mineral admixtures (CMAs) containing the high-volume GGBFS, basalt powder, and desulfurization gypsum were investigated. The results showed that the mortar strengths at 3, 7, and 28 days decreased with increasing GGBFS content, but that at 56 and 84 days increased with the addition of 45 wt.% GGBFS. This is because the activity of GGBFS at early stage has not been stimulated and the pozzolanic effect is exerted at later stage. Moreover, cement replacement with up to 55 wt.% GGBFS caused a significant decrease in the chloride diffusion coefficient of the mortar and concrete. Furthermore, the incorporation of GGBFS led to a remarkable refinement in pore structure of the hardened paste due to the pozzolanic and filler effects. Therefore, the partial replacement of cement with high CMA contents (≥ 70 wt.%) in concrete is desirable for ocean projects requiring low chloride permeability and significantly reduces carbon emissions.