Experimental study on the compressive mechanical behavior and constitutive model of basalt fiber reinforced coral concrete

Coral concrete characterized by the high porosity and brittleness of its aggregates, exhibits suboptimal mechanical properties. This study investigates the mechanical behavior of basalt fiber-reinforced coral concrete (BFRCC) under uniaxial compression. Ten groups of specimens, incorporating different fiber lengths and volume fractions, were subjected to compressive testing. A comparative analysis was conducted on the mechanical properties including compressive failure pattern, peak stress, peak strain, ultimate strain, and elastic modulus. The deformation and crack propagation processes of specimens were investigated using Digital Image Correlation (DIC) technology. Based on experimental findings, a modified constitutive equation was proposed. Furthermore, the microstructure of BFRCC was characterized through Scanning Electron Microscopy (SEM), providing insights into the reinforcing mechanism of basalt fibers. The results show that basalt fiber incorporation modifies the failure characteristics of coral concrete while substantially improving its mechanical performance. Through physical filling effects and interfacial bonding mechanisms, basalt fibers optimize the matrix pore structure, thereby delaying strain localization and enhancing both ductility and crack resistance. The developed constitutive model demonstrates reliable predictive accuracy for the stress-strain behavior of BFRCC. This study provides crucial theoretical foundations and practical guidelines for mechanical characterization and performance enhancement in fiber-reinforced coral concrete systems.