Mechanical properties and constitutive model of basalt-fibre-reinforced coral aggregate seawater concrete under triaxial compression

The mechanical properties of basalt-fibre-reinforced coral aggregate seawater concrete (BFCAC) under triaxial compression were investigated, with the aim of addressing the challenges of high transportation costs and the scarcity of materials in island and reef engineering. The experimental work involved preparing cylinder specimens with varying basalt fibre (BF) volume fractions (0.25%, 0.30% and 0.35%) and subjecting them to different lateral confining pressures (0, 3, 6, 9 and 12 MPa). The results showed that the BFCAC had reduced brittleness compared with plain coral aggregate seawater concrete, with failure patterns shifting from longitudinal cracking to diagonal shear failure under triaxial loading. The peak stress of the BFCAC increased significantly with higher lateral confining pressures, with the peak stress at 12 MPa being 222.2% higher than that at zero confining pressure. The optimal BF volume fraction was found to be 0.25%, which maximised both peak stress and elastic modulus. A constitutive model for BFCAC under triaxial compression was proposed and the model demonstrated good agreement with the experimental data, providing a reliable basis for the design of BFCAC structures.