Study on mechanical properties and damage characteristics of rubber concrete under equal amplitude high stress repeated loading

The reuse of waste rubber in concrete is beneficial for sustainable development of ecological environment. Rubber concrete is often under repeated loading during its service. In this paper, the deterioration characteristics of rubber concrete under equal amplitude high stress repeated loading were analyzed and discussed. Three rubber particle sizes (0.85 mm, 1–3 mm, and 3–6 mm) and a content of 10% of rubber concrete, and ordinary concrete were prepared, which expressed as RC-A, RC-B, RC-C, and OC. The apparent phenomenon, mechanical properties, and stress–strain curve of concrete during repeated loading were tested. The results showed that with the increase in rubber particle size, the peak strain and residual stress increased, and compressive strength and elastic modulus decreased. The damage degree of concrete under repeated loading was calculated by energy dissipation method. Rubber concrete has great damage after the first cycle of loading, and the damage degree increases slowly with the increase of loading cycle number. However, OC has no obvious damage after the first cycle of loading, and the damage degree increase with the increase of loading cycle number, which indicates that rubber concrete has larger deformation and elasticity than those of OC, showing better stability. By the apparent and microscopic analysis, the process of concrete damage by repeated loading is micro-crack generation and growth under loading compression, and the micro-crack closure under unloading, until the macro-damage appears in concrete. The mechanical properties of each group of concrete are evaluated by the analysis of efficiency coefficient, the scoring order is RC-A > RC-B > OC > RC-C. The results show that the best rubber particle size is 0.85 mm.