Experimental and modelling investigation of stress-strain behavior of basalt fiber-reinforced coral aggregate concrete under uniaxial and triaxial compression

Abstract

The use of basalt fibre-reinforced coral aggregate concrete (BFRCAC) facilitates the sustainable utilization of coral waste and helps mitigate terrestrial sand and gravel shortages. In addition, concrete structures experience complex multiaxial stress states in service. Therefore, uniaxial and triaxial compression tests were conducted to examine the influence of the confining pressure ratio, basalt fiber (BF) content, and concrete strength grade on the mechanical performance of BFRCAC. The test results showed that the confining pressure altered the failure pattern of BFRCAC, indicating that it was the most influential factor. An increase in the confining pressure ratio significantly enhanced the characteristic parameters of the stress–strain curves of specimens with different strength grades. The increments in peak stress, peak strain, initial elastic modulus, and compressive toughness were 248.09 %, 250.72 %, 52.62 %, and 1570.44 %, respectively. The incorporation of BFs effectively reduced the degree of failure and enhanced the mechanical properties of the specimens, particularly post-peak compressive toughness, with an optimal fiber content of 0.8 %. Meanwhile, the reinforcing effect of BFs was more pronounced under low confining pressure. However, an increase in either strength grade or confining pressure ratio diminished this reinforcing effect. Finally, a damage constitutive model applicable to various confining pressure ratios, basalt fiber contents, and concrete strength grades was established, and expressions for key mechanical parameters were derived. The proposed model can accurately predict both the stress–strain development and damage evolution of BFRCAC under uniaxial and triaxial compression, providing a theoretical basis for its engineering application.