Evaluation on comprehensive properties and bonding performance of practical slag-fly ash blending based alkali-activated material

Abstract

Alkali-activated materials have been considered as the potential alternative repair materials to persuade concept of sustainability due to low energy consumption. Ecological benefits increased on their applications have been associated with utilization of more environmental-friendly chemical activator. The current study dealt with engineering and drying shrinkage performances of an alkali-activated blending of slag and low calcium Class F fly ash (FFA) paste (AASF) with sodium hydroxide (NaOH) and also its’ bonding performance with blended Portland cement (PCB). Effects of Na 2 O concentration varied at four values of 3, 4, 6, and 8 mass.% of total solid fraction and FFA addition partially replacing slag at three values of 10, 30, and 50 mass.% on engineering performances of the AASF pastes were initially evaluated. After optimizing analysis, selected AASF mixtures were used for assessing their bonding performances with the PCB paste at equivalent 7-day compressive strength grade. Experimental results showed that the concentration of Na 2 O in range of 4–6 mass.% of total solid was considered as the optimum value to produce the practical AASF pastes with the best 28-day compressive strengths. But, the increase in Na 2 O concentration in the optimized range negatively impacted drying shrinkage and bonding performance of the resultant AASF, which was in opposite to the effect of FFA addition partially replacing slag in range of 10–30 mass.%. • Comprehensive engineering properties and bonding performance of slag-fly ash blending based AAM based repair material were evaluated. • Concentration of Na 2 O negatively impacted drying shrinkage and bonding performance of AAM. • Fly ash addition significantly improved drying shrinkage and bonding performance of AAM.