Effect of Electric Arc Furnace Slag Fine Aggregate on Compressive Strength of High-Strength Mortar

The depletion of natural high-quality aggregates has hindered the sustainable and stable supply of high-strength concrete recently. This study investigates the effect of electric arc furnace slag fine aggregate (ES) on the strength of high-strength mortar, the fundamental matrix of high-strength concrete (water binder ratio of 0.20 and 0.30) to make effective use of resources. The compressive strength and elastic modulus of mortar using the ES were improved compared to those using normal fine aggregate. Three critical aspects, interfacial properties of aggregate, surface characteristics of aggregate, and intrinsic strength of aggregate, were investigated to elucidate the strengthening mechanism of ES. These results indicated that the critical feature is that ES has higher strength and elastic modulus than normal fine aggregate. Considering mortar as a two-phase material consisting of fine aggregate phase and cement paste phase, it can be concluded that the improvement in the strength of high-strength mortar using ES is achieved by the positive effect of distributing the stress induced on cement paste phase in mortar to rigid ES phase. These findings highlight that ES not only contributes to sustainable resource circulation but also has the potential to realize the cementitious materials with superior mechanical performance.