Abstract:In order to study the difference of fracture process of concrete with different moisture contents, the dry specimen was soaked for different time to reach different moisture contents. The failure process of three-point bending beam was monitored by acoustic emission technique. Comparing the difference of acoustic emission signals, such as hit, count and energy, was applied reflect the different effects of different moisture contents on the mechanical behavior of concrete fracture process, and combined with the hit, count and energy to catch up the initial fracture load, further analysis influences of the initial fracture toughness and unstable fracture toughness on different moisture contents was carried out. The experimental results showed that the variation law of acoustic emission parameters could more intuitively analyze the influence of moisture content on the fracture process of concrete compared with the P–CMOD curve. As moisture content increased, before initiation fracture, the accumulative value of hit increases, however after initiation fracture, the values of acoustic emission parameters of peaks and accumulative values all decreasd. The threshold value of damage evolution decreased with the increase of moisture content, and the maximum was decreased by 64% at saturated content from the value in completely dry condition. The width of the fracture process zone of the saturated specimen increased by 20.8% compared with the dried specimen.