Experimental study on thermo-hydro-mechanical responses of concrete plates subjected to in-plane compressive loading and one-side heating

This paper investigated experimentally the thermo-hydro-mechanical responses of pre-dried and saturated concrete plates subjected to in-plane compression and one-side heating. Three concrete plates for each of three grades were designed: one was saturated and then heated; one was saturated, loaded and then heated; the remaining one was pre-dried, loaded and then heated. During the heating and cooling process, the force, strain, temperature, pore pressure and cracking responses were measured and analyzed. Test results showed that compressive loads could increase fire spalling risks of saturated concrete by inducing principal cracks parallel to the exposed surface. However, the indispensable contributions of moistures to the formation of principal cracks indicated by crack responses were not consistent with those indicated by measured negligible pore pressures. For the same aggregate proportion, the thermal field was hardly affected by water-cement ratio or concrete grade/ strength. During the heating process, for any given initial in-plane load, thermal dilation and softening competed causing load increases or decreases, but eventually softening outweighed thermal dilation. In addition, longitudinal strain distributions evolved on average toward the less compressed direction; meanwhile, time-strain curves showed jumps toward the less compressed direction, which might be caused by the local swellings due to clogged moisture/water layers.