Effects of dosage of alkali-activated solution and curing conditions on the properties and durability of alkali-activated slag concrete

Abstract

This study presents an investigation into physical and mechanical properties and durability of alkali-activated slag concrete (AASC). Sodium oxide (Na2O) concentrations of 4%, 5% and 6% of slag weight and liquid sodium silicate with modulus ratio (mass ratio of SiO2 to Na2O) of 0.8 were used as alkaline activators to activate granulated blast furnace slag (GBFS). Specimens with/without phosphoric acid (H3PO4) were cast and cured in the air, under the saturated limewater and in a curing room at relative humidity of 80% RH and temperature of 60°C, respectively. Their performance was discussed and compared with reference concretes produced using ordinary Portland cement concrete (OPC). Test results show that both the dosage of Na2O and H3PO4 of additional mixture are significant factors influencing the properties of the fresh AASC mixtures. In hardened concrete, better properties and durability, such as compressive strength, splitting tensile strength, drying shrinkage, total charge passed, high-temperature resistance and sulphate attack resistance, have been obtained in AASC than comparable OPC. The properties and durability of AASC were significantly dependent on dosage of Na2O and curing conditions. The properties and durability of AASC improved with an increase dosage of Na2O and AASC cured at relative humidity of 80% RH and temperature of 60°C has the superior performance, followed the AASC by air curing and saturated limewater curing based on the presented observations and results.