Optimising cement systems containing amorphous precipitated silica derived from olivine, limestone and gypsum

Amorphous precipitated silica (APS) derived from olivine has potential to be used as a pozzolanic supplementary cementitious material, but high specific surface area reduces mix workability, accelerates sulphate depletion and decreases early age strength. This study investigates the feasibility of blending Portland cement with APS, limestone and gypsum to address these issues. Quaternary binders containing 5 – 20 wt.% limestone and 2 wt.% gypsum were prepared at CEM I: APS mass ratio of 8:2. Results show that limestone improves workability and early hydration reactions, while gypsum stabilises sulphate availability and promotes strength development. Mortars with a binder system containing 10 wt.% limestone with 2 wt.% gypsum show comparable workability and strength to control mortars. The research demonstrates that olivine-derived APS can be combined with limestone and gypsum to form a viable low-carbon cement with reduced clinker content.