Material and structural properties of recycled coarse aggregate concrete made with seawater and sea-sand: A review

This paper presents a review of the research on seawater sea-sand recycled coarse aggregate concrete (SSRAC), which offers a solution to the scarcity of river sand and freshwater while also promoting the reuse of waste concrete. The study reveals that the conventional mix proportion design method underestimates the compressive strength of SSRAC at 28 days. The incorporation of seawater and sea-sand reduces the negative effects of recycled coarse aggregate (RCA) on compressive properties, compensating for the decreased mechanical properties of components made with RCA. Additionally, it enhances the bond strength between concrete and epoxy-coated bars while it has a lesser effect on that between concrete and fiber reinforced polymer (FRP) bars. Nevertheless, it appears to have adverse effects on workability and tensile properties. The primary factors influencing the stress-strain curves of SSRAC are RCA, shell content, and chloride ion concentration. The effective confinement of FRP and the stiffness of FRP bars are crucial considerations in the design of SSRAC components. Furthermore, the combination of SSRAC with other types of concrete offers an alternative design approach. Finally, this paper identifies research needs for SSRAC, with a focus on durability and time-dependent properties.