A critical review on structural behavior of alkali-activated concrete beams

The increasing demand for sustainable development in engineering practice has triggered researchers to explore solutions to reduce the CO2 footprint caused by ordinary Portland cement (OPC) production. Alkali-activated concrete (AAC), made of by-products using alkali activation, is of great potential as a promising alternative to conventional concrete (CC). Despite vast studies on its material properties, there is still insufficient scientific research on the structural performance of AAC, which impedes its widespread application. In this paper, an overview of the fundamental behavior of AAC beams under different loading conditions is presented. The experimental investigations on mechanical performance of AAC beams are reviewed in terms of ultimate capacity, ductility and cracking behavior. Moreover, numerical methods to predict AAC structural response as well as the applicability of existing CC design codes are summarized. It is concluded that AAC beams show comparable short-term behavior with CC counterparts. Besides, the design codes for CC turn out to be applicable but conservative for most steel-reinforced AAC beams. Though short-term flexural behavior has been widely investigated for AAC beams, the challenge remains to clarify shear behavior and long-term behavior. Furthermore, reliable guidelines are needed to be developed, providing recommendations for future structural design.