Mesoscale analysis of rubber particle effect on flexural strength of crumb rubber concrete

Flexural strength is an indirect indicator for measuring the concrete's resistance to tensile stress caused by bending, shrinkage and temperature changes. This study aims to study the flexural strength of crumb rubber concrete (CRC) through mesoscale simulation and experimental testing. The internal structure of CRC was regarded as a five-phase material consisting of rubber, coarse aggregate, mortar, coarse aggregate-mortar interfacial transition zone (A-M ITZ), and rubber-mortar interfacial transition zone (R-M ITZ). The flexural strength of CRC specimens containing rubber particles of different contents, shapes, and sizes was calculated and compared. Mesoscale simulation showed that the addition of rubber reduces the flexural strength of concrete, and the reduction rate is mainly controlled by the content rather than the size, shape, and distribution of rubber particles. The thickness of R-M ITZ is around 0.05 mm, and its effect on the flexural strength of CRC is as low as 1.15% which can be ignored. The incorporation of rubber particles increases the heterogeneity of the internal structure of concrete, which increases the discreteness of the concrete's flexural strength. Numerical simulation also verified that treating the rubber particles as pores did not change the damage pattern of the CRC specimens and resulted in negligible differences in flexural strength. Rubber particles can be simulated through pores when analyze their effect on the flexural strength of concrete.