Effect of curing regime and temperature on the compressive strength of cement-slag mortars

In this experimental work 24 mixes were prepared. Each mix was made using binder contents 380 and 500 kg/m3. All the made mixes are classified into three groups as OPC, OPC-slag and slag mortars. Each group includes eight mixes and the specimens were cured in different curing regimes after casting and demoulding, i.e. under room temperature (ac), in water without heating (wc), room temperature after heating 60 °C for duration 20 h (WH/ac) and in water after heating like as mentioned (WH/wc). The results showed that the highest strength is related to the OPC-slag mortars as 80 MPa for OSM380-wc. For all groups of mortars, there could rarely be strength loss at later ages. The results proved that WH/ac is the optimum curing regime for all groups of mortars in duration of 3–7 days, whereas the optimum curing regime is not the same in duration of 28–90 days. It was proved that higher strength could be achieved for OPC and OPC-slag mortars using lower binder content provided the specimens are cured in water without heating. This reality is reversed for slag mortars; namely for slag mortars the highest strengths could be only achieved using more slag content and water curing without heating. For SM500-wc the strengths obtained at 28 and 90 days were as 18 and 26 MPa, respectively.

► WH/ac is the optimum curing regime for all groups of mortars in duration of 3–7 days. ► The optimum curing regime is not the same for all groups of mortars in duration of 28–90 days. ► Higher strengths achieved for OPC and OPC-slag mortars using lower binder content and curing regime wc. ► The strength of OSM380-wc at 90 days was obtained as 80 MPa. ► The highest strength for slag mortars could be only achieved using more slag content and curing regime wc.