Bond performance of reinforced alkali-activated composites using water-quenched slag as alternative fine aggregates

Abstract

Pull-out tests and beam-end tests were conducted to study the bond performance of reinforced alkali-activated composites (AAC). A steelmaking waste, water-quenched slag (WQS), was employed as an alternative to river sand fabricating the AAC. The pull-out tests aimed at examining the bond performance of the AAC incorporating different volumes of WQS and embedded different reinforcements. The beam-end tests simulated the stress mode of flexural member and studied the effect of some structural parameters on the bond performance, including the thickness of the concrete covering (Cc), the bond length (la) and the space between two adjacent stirrups (Sst). The results indicated that AAC brought reinforced-concrete specimens better bond performance compared to the ordinary Portland cement (OPC) concrete because of the chemical adhesion between the AAC and steel reinforcements. The involvement of WQS contributed to strong friction effect between the rebar and mortar matrix, which played a role in improvement of bond performance. The results of the beam-end tests revealed that the thickness of concrete cover was an influential factor on the bond performance, and the influence of the other structural parameters on the bond performance relied on the thickness of concrete cover. Based on the tests results, a fitting model was proposed to predict the bond strength using the splitting tensile strength of AAC.