Recycling of waste oyster shell and recycled aggregate in the porous ecological concrete used for artificial reefs

Reinforced concrete is currently used as the main material to prepare the artificial reef which suffers from poor ecological performance, such as high alkalinity and poor biological attachments. Therefore, this study used the waste oyster shell (WOS) and recycled aggregate (RA) to prepare the artificial reef by using porous ecological concrete (PEC), aiming to improve the interconnected porosity, compressive strength, sulfate attack resistance, and alkalinity. The experiment results show that the addition of WOS and RA present excellent compatibility in the PEC and affect the interconnected porosity less. The compressive strength and sulfate attack resistance of PEC decreases gradually with the increasing contents of WOS and RA. In this case, the content of WOS should not exceed 20%, and the RA can totally replace natural aggregate (NA) in PEC, which meets the requirements for preparing artificial reef. Additionally, the lowest pH value of the 28d leaching solution of PEC reaches 8.52, which is closely to that of seawater, and the biological attachments of PEC are greatly improved. In conclusion, the PEC prepared by WOS and RA presents potential application in artificial reefs with enhanced ecological performance.