Steel rebar corrosion in artificial reef concrete with sulphoaluminate cement, sea water and marine sand

Abstract

To reduce the surface alkalinity of artificial reef concrete (ARC) and save fresh water and natural aggregate resources, a new artificial reef concrete (NARC) made with sulphoaluminate cement (SAC), sea water and marine sand was proposed in our previous work. However, the steel corrosion as a major concern associated with NARC has not been explored. In this paper, the effects of cement type (SAC, ordinary Portland cement (OPC), mixed cement of OPC and SAC) on the chloride permeability and capillary water absorption of sea water and marine sand-based ARCs were studied. The anodic polarization and loss of steel rebar weight were used to evaluate the effects of the cement type and corrosion inhibitor on the corrosion of steel rebars in ARCs. The results of the present work show that for sea water and marine sand-based ARC, SAC significantly improves the microstructure and decreases the chloride penetration and the water absorption rate. Meanwhile, due to the high chloride binding rate of SAC, the corrosion degree of rebars in NARC is less than that of sea water and marine sand-based ARC with OPC and mix cement of OPC and SAC. Compared with ordinary ARC (ARC made OPC, fresh water and river sand), the steel rebar corrosion in NARC is more serious. Nevertheless, a 2% dosage of corrosion inhibitor (TEA) can significantly decrease the steel rebar corrosion in NARC to a similar corrosion degree of ordinary ARC. The feasibility of using marine sand and seawater in SAC-based ARC is verified.