Review on the Mechanical Properties and Modification Techniques of Coral Concrete

Coral aggregate concrete (CAC) serves as a critical material for sustainable development in marine engineering, effectively addressing the shortage of aggregate resources in the construction of offshore islands and reefs. In this paper, the aggregate characteristics, static and dynamic mechanical properties and modification technology of CAC are systematically reviewed. Research indicates that the coral aggregates (CAs), due to its high porosity (approximately 50%), low bulk density (900-1100 kg/m³), and rough, porous surface, results in relatively low static compressive strength (20-40 MPa), insufficient elastic modulus, and significant brittleness in CAC. However, its dynamic performance shows the opposite advantage. Under impact loads, the energy absorption capacity is enhanced by 32.6-140.3%, compared to ordinary concrete (OC) due to the energy dissipation mechanism of pore platic deformation. Through the modification techniques, such as aggregate pre-treatment (acid washing/coating), incorporation of auxiliary cementitious materials (silica fume increases strength by 16.4%), fibre reinforcement (carbon fibres enhance flexural strength by 33.3%), and replacement with novel cementitious materials (magnesium sulphate cement improves chloride ion binding capacity by 90.7%), the mechanical properties and durability of CAC can be significantly optimised. This paper highlights gaps in current research regarding the high strain rate (>200 s^-1) dynamic response, multi-factor coupled durability in marine environments, and the engineering application of alkali-activated materials, providing theoretical basis for future research directions.