Experimental investigations on the structural performance and calculation analysis of reinforced alkali-activated materials (AAMs) beams

Alkali activated materials (AAMs) concrete incorporating GGBFS and FA as precursors is an alternative to the conventional OPC-based concrete. In order to take fully use of industrial wastes, river sand was partially replaced by water quenched slag (WQS) as fine aggregates fabricating AAMs concrete. It is essential to investigate the performance of reinforced AAMs concrete members based on the material properties as well as the constitutive models. Although some existing concrete structure codes have been used to design conventional reinforced concrete structures authoritatively, there would be a deviation caused by the codes being used to estimate the properties of AAMs concrete structures. In this study, the structural properties of reinforced AAMs concrete beams were initially investigated by conducting four-point bending tests. Specially, six beams with different reinforcement ratios were fabricated and tested in static loads. It was found that the failure modes, crack patterns and deflections of the six AAMs concrete beams were similar to those of conventional RC beams. Compared to the experimental results, structural properties including cracking moment and moment capacity were estimated according the methods recommended by three existing concrete structure codes ACI-318, AS 3600-2018 and GB 50010-2010, respectively. As a result, the calculated cracking moment and the moment capacity of the six AAMs concrete beams were underestimated by 40% and more than 10%, respectively. Based on the constitutive models of the AAMs concrete, nonlinear stress–strain distributions in the cracking state and ultimate state were proposed to establish calculation methods for the structural performance evaluations. The cracking moment and the moment capacity calculated via the proposed methods matched the experimental results well, by the average deviation of 1.2% and 4.2% respectively.