Mechanical Test and Meso-Model Numerical Study of Composite Rubber Concrete under Salt-Freezing Cycle

Abstract

A composite rubber concrete (CRC) was designed by combining waste tire rubber particles with particle sizes of 3~5 mm, 1~3 mm and 20 mesh. Taking the rubber content of different particle sizes as the influencing factors, the range and variance analysis of the mechanical and impermeability properties of CRC was carried out by orthogonal test. Through analysis, it is concluded that the optimal proportion of 3~5 mm, 1~3 mm, and 20 mesh particle size composite rubber is 1:2.5:5. 5 kinds of CRC and 3 kinds of ordinary single-mixed rubber concrete (RC) with a total content of 10%~20% were designed under this ratio, and the salt-freezing cycle test was carried out with a concentration of 5% Na2SO4 solution. The physical and mechanical damage laws during 120 salt-freezing cycles are obtained, and the corresponding damage prediction model is established according to the experimental data. The results show that: on the one hand, the composite rubber in CRC produces a more uniform “graded” structure, forms a retractable particle group, and reduces the loss of mechanical properties of CRC. On the other hand, colloidal particles with different particle sizes are used as air entraining agent to improve the pore structure of concrete and introduce evenly dispersed bubbles, which fundamentally improves the durability of concrete. Under the experimental conditions, the CRC performance is the best when the overall content of composite rubber is 15%.