Li Ping, Liu Ji, Duan Shiwei, Huang Ruiyuan
School of Mechanical Engineering, Anhui University of Technology, Maanshan 243032, China.
College of Civil Engineering, Fuzhou University, Fuzhou 350116, China.
Materials (Basel). 2023 Feb 13;16(4):1548. doi: 10.3390/ma16041548.
The compressive strength of concrete is not the same in high temperature humid environments and normal temperature dry environments. In this study, quasi-static uniaxial compression experiments of concrete with different temperatures and water contents were carried out to investigate the variation pattern of the compressive strength of concrete under combined heat and moisture conditions. The results showed that the temperature softening effect and water softening effect of the compressive strength of concrete were coupled with each other. The compressive strength exhibited a variation trend from increase to decrease with the increase in both temperature and water content, and the relations among the heat-moisture coupling factor, temperature, and relative saturation ratio were obtained. The water absorption of concrete after immersion had a more significant effect on the compressive strength than the free water content stored inside the specimen before immersion. The "pseudo-temperature strengthening effect" distinguished the thermodynamic response of immersed concrete from that of dry concrete, and the functional relationships among the heat-moisture coupling factor, temperature, and relative water absorption ratio were established. The evolutionary mechanism of the competition between the microcrack expansion and healing of concrete under combined heat and moisture conditions was revealed.
混凝土的抗压强度在高温潮湿环境和常温干燥环境中并不相同。在本研究中，对不同温度和含水量的混凝土进行了准静态单轴压缩试验，以研究湿热耦合条件下混凝土抗压强度的变化规律。结果表明，混凝土抗压强度的温度软化效应和水软化效应相互耦合。抗压强度随温度和含水量的增加呈现出先增大后减小的变化趋势，并得到了湿热耦合因子、温度和相对饱和度之间的关系。浸泡后混凝土的吸水率对抗压强度的影响比浸泡前试件内部储存的自由水含量更为显著。“假温度强化效应”区分了浸泡混凝土和干燥混凝土的热力学响应，并建立了湿热耦合因子、温度和相对吸水率之间的函数关系。揭示了湿热耦合条件下混凝土微裂纹扩展与愈合竞争的演化机制。
