Effect of elevated curing temperature on ceramsite concrete performance

The good overall properties of ceramsite concrete give it more potential value in the application of shotcrete lining in high geothermal environments. In this study, an orthogonal experiment was employed firstly to determine an optimum mix proportion for ceramsite concrete at a curing temperature of 20 °C, 40 °C and 60 °C, and then an accelerating agent was added to the concrete mixture. As a result, compared with the 20 °C curing condition, the long-term compressive strength of ceramsite concrete cured at 60 °C decreased significantly and declined even more on account of the accelerating agent, nevertheless the long-term compressive strength cured at 40 °C decreased only when the accelerating agent was added. The ceramsite concrete exhibited good permeability resistance and thermal insulation. And as the curing temperature raised the permeability resistance decreased, whereas the thermal insulation increased. The variation of microstructure with curing temperature was analyzed by scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP). The compressive strengths at certain curing temperatures were plotted against the curing age, and correlation functions were established.