Durability of coral aggregate concrete under coupling action of sulfate, chloride and drying-wetting cycles

This paper investigates the deterioration progress of coral aggregate concrete (CAC) under the coupling action of sulfate, chloride and drying-wetting cycles. Three strength grades (C25, C30, C40) of CAC specimens were designed for experimental analysis. In addition, ordinary aggregate concrete (OAC) specimens were prepared as the reference group. The relative dynamic elastic modulus and the relative compressive strength of CAC increases first and then decreases with increasing exposure time, while the mass loss rate shows the opposite trend. The CAC with high strength grade has strong corrosion resistance, and the corrosion resistance of CAC is obviously lower compared to OAC at same strength grade. The addition of basalt fiber into CAC can delay the cracking and maintain the integrity. With increasing exposure time, the damage depth increases exponentially. The chloride concentration can be divided into two phases: first increase and then decrease. Basalt fiber can significantly reduce the chloride diffusion coefficient of CAC. The erosion products are ettringite and gypsum for OAC and CAC; in addition, Friedel's salt is also found in CAC.