Triaxial compressive behavior and failure criterion of PVA fiber-reinforced rubberized concrete

Fiber-reinforced rubberized concrete has been widely investigated and applied due to its excellent toughness. However, it is often subjected to multiaxial compression in service, and its triaxial mechanical response and failure criterion have rarely been reported. Triaxial compression tests were performed to evaluate how fiber dosage influences the mechanical response and failure criterion of rubber-powder concrete under different levels of confining pressure. Failure patterns, stress-strain responses, peak stress, elastic modulus, and peak strain were evaluated. The results show that, with rubber powder incorporation, increasing fiber content markedly reduces crack opening and makes crack propagation paths more tortuous, driving an overall transition from brittle cracking to a more ductile and energy-dissipative failure mode. Fibers mainly modify the post-peak response by producing a smoother stress decay and improved residual load-carrying capacity. These benefits are more evident at confining pressures of 4 and 8 MPa, whereas at 12 MPa the response is increasingly governed by triaxial constraint and the differences among fiber dosages diminish. Increasing confining pressure significantly enhances the peak stress and alters the failure mechanism. Rubber powder reduces the peak stress, but its adverse effect is progressively mitigated as confinement increases. Based on the peak-strength data, a power-law failure criterion incorporating the fiber-dosage effect was established. The proposed criterion can predict the ultimate strength of rubberized concrete under multiaxial compression with good accuracy.