Experimental Study and Failure Criterion Analysis of Rubber Fibre Reinforced Concrete under Biaxial Compression-Compression

Abstract

In order to examine the biaxial compression-compression properties of rubber fibre reinforced concrete (RFRC), an experimental study on RFRC under different lateral compressive stresses was carried out by considering different rubber replacement rates and polypropylene fibre contents. The failure modes and mechanical property parameters of different RFRC working conditions were obtained from the experiment to explore the effects of rubber replacement rate and polypropylene fibre content on the biaxial compression-compression properties of RFRC. The following conclusions were drawn. Under the influence of lateral compressive stress, the biaxial compression-compression failure mode gradually developed from a columnar pattern to a flaky pattern, suggesting that the incorporation of rubber and polypropylene fibres into the concrete resulted in a significant change in the development of cracks. For different rubber replacement rates and polypropylene fibre contents, the vertical compressive stress exhibited the same developing trend under the influence of lateral compressive stress. Specifically, the lateral compressive stress imposed the minimum effect on the vertical compressive stress when the rubber replacement rate and polypropylene fibre content were 20% and 0.4%, respectively, and imposed the maximum effect when the rubber replacement rate and polypropylene fibre content were 20% and 0%, respectively. With the increase of rubber replacement rate, the vertical peak stress was significantly reduced, which implies that an appropriate amount of polypropylene fibres can increase the vertical peak stress to a certain extent. Then, the biaxial compression-compression mechanism of RFRC was analysed from the microscopic level by using scanning electron microscope (SEM). Meanwhile, based on Kupfer’s biaxial compression-compression failure criterion and the octahedral stress space, a biaxial compression-compression failure criterion for RFRC was proposed, which was proven to have good applicability. The research results of this study provide important theoretical basis for the engineering application and development of RFRC.