Effect of type and dosage of alkaline activators on the mechanical properties of alkali-activated slag concrete complied with ASTM C150

Portland cement (PC) is the most widely used material in the world. Cement production is one of the leading industries that cause pollution and emission of greenhouse gases. Alkali-activated cement concrete (AACC) has received particular attention as a suitable alternative to Portland cement concrete due to its acceptable properties and environmental impact. In this research, the type and amount of alkaline activator on the mechanical properties and workability of alkali-activated slag concretes are investigated. For this purpose, two types of sodium hydroxide and powdered sodium silicate activators were used in amounts of 2, 6, 10, and 14 weight percent of slag. The flexural and compressive strength of the concretes, were measured after 3, 7, 28, and 90 days of curing in water at a temperature of 20±2°C. X-ray fluorescence (XRF) and X-ray diffraction (XRD) were used for Chemical and phase analysis of slag. The flexural and compressive strength of the samples were measured according to ISO 679 and the results were compared with ASTM C150 requirements. The results showed that the highest strength was obtained in the sample with 10% sodium hydroxide and 6% sodium silicate. The strength value in 90 days is higher in the sample activated with sodium silicate than the sample activated with sodium hydroxide. The results of comparing the mechanical properties of the samples with PC, disclosed that AASC could be a suitable alternative to Portland cement.