Potential pozzolanicity of Algerian calcined bentonite used as cement replacement: optimisation of calcination temperature and effect on strength of self-compacting mortars

The effect of using calcined bentonite (CB) as a partial replacement for Ordinary Portland cement (OPC) in self-compacting mortar (SCM) is investigated. The pozzolanicity of this calcined clay is evaluated using the strength activity index and TG/ATD analysis. The cement in SCM has been replaced with CB at 0, 5, 10, 15, 20, 25 and 30% by mass of cement. The effect of CB on fresh SCM properties is examined using mini-slump flow and V-funnel flow time. The compressive strength is determined at the age of 3, 7 and 28 days, and the ultrasonic pulse velocity (UPV), hardened density and water absorption are determined at the age of 28 days. The behaviour of SCM exposed to high temperature is also studied. The results indicate that CB significantly decreased the flowability of SCM, but these results are good enough for SCM and SCC production. Incorporating 10 and 15% of CB improves the compressive strength and UPV. Water absorption tends to increase slightly with an increase in CB content and there is a decrease in density as the amount of CB increases. SCM containing CB is stronger when exposed to high temperature than those exposed to normal temperature (23 °C).