Compressive Performance and Damage Analysis of Coral Seawater Sea Sand Concrete After High Temperature

Although concrete is non-combustible, it experiences a decline in mechanical properties when exposed to high temperatures. This study investigates the impact of varying temperatures (T) and constant exposure durations (H) on the mechanical performance degradation of coral aggregate concrete. Coral seawater sea sand concrete (CSSC) was produced using equal proportions of coral aggregates, seawater, sea sand, and P•O 42.5 cement. The compressive failure characteristics of CSSC were analyzed under different T and H conditions. To characterize the mechanical properties, compressive tests were conducted on 30 sets of 150 × 150 × 150 mm cubic specimens. The resulting stress–strain curves were used to determine the influence of T and H. The results indicate that the compressive strength (f _cu ^T ) and elastic modulus (E ₀) of CSSC decrease with increasing temperature. At T = 800°C, the f _cu ^T of CSSC is reduced to 27.8% of its original value at 25°C, while the E ₀ decreases to 9.7%. Additionally, the mass loss rate (I _w ) and volume expansion rate (R _s ) increase with rising temperature. At T = 800°C, the I _w reaches 12%, and the R _s reaches 7.1%. Finally, the stress–strain constitutive model of concrete after high temperature was fitted to the experimental data.