Abstract
Recycling rubber aggregates from used grinded tires is a behavior of environmental protection. By performing cyclic flexural tests, this paper explores the effect of rubber aggregate content on the crack propagation of notched concrete beams containing waste rubber aggregates. The crack mouth opening displacement is tested. The acoustic emission technique is applied to detect the damage in the fracture process zone. The crack propagation is evaluated using the critical value of the mode I stress intensity factor. It was found that the crack length and stress intensity factor decrease with the increasing of rubber aggregates content. The crack length and stress intensity factor at failure under constant cyclic loading are larger than those at corresponding post-peak load level. It was observed that the damage evolution curves under cyclic envelope loading can be divided into three stages: initial-quick-stable stages. And they are S-shaped, quick-stable-accelerated curves under constant cyclic loading. Rubber aggregate reduces the acoustic emission activities in concrete specimens. Accumulations of acoustic emission hits, acoustic emission counts and acoustic emission energy are found in accordance with the damage evolution of concrete beam. The relation between damage and accumulative acoustic emission hits is quantified by fitting experimental data. The fitting curves agree well with test results.
