水胶比对RPC高温抗爆裂及残余力学性能的影响研究

通过制备不同水胶比的RPC120级活性粉末混凝土,研究了不同水胶比的RPC试件在200~1000℃内抗高温爆裂性能及强度和质量损失率随温度的变化规律。对高温后试件进行了断面结构观察,并结合热重分析(TG)及差示扫描量热分析(DSC),研究了RPC高温作用后的性能变化机理。结果表明,水胶比在0.18~0.21范围内,0.18组的RPC抗高温爆裂能力及力学性能是最优的;不同水胶比的RPC强度随着受热温度的升高,都呈现出先增大再减小的趋势,抗压强度的临界温度为300℃,抗折强度的临界温度为200℃。在20~300℃,RPC高温性能的变化是由水化产物中自由水和结合水的失去所致,300~1000℃是水化产物的分解和钢纤维的氧化造成的。

Study on the Effect of Water-binder Ratio on the High Temperature Burst Resistance and Mechanical Properties of RPC

The reactive powder concrete(RPC120)with different water binder ratio was prepared.The high temperature burst resistance,strength and mass loss rate of RPC specimens with different water binder ratio in the heating range of 200~1000℃were studied.The cross section structure of the specimens after high temperature was observed.The mechanism of RPC performance change after high temperature was studied by TG and DSC.The results show that when the water-binder ratio is in the range of 0.18~0.21.The high temperature burst resistance and mechanical properties of RPC with water-binder ratio of 0.18 are the best.The compressive strength of RPC with different water-binder ratio increases first and then decreases.The critical temperature of strength is 300℃and the critical temperature of flexural strength is 200℃.At 20~300℃,the change of RPC′s high temperature performance is caused by the loss of free water and binding water in the hydration products,and the change at 300~1000℃is resulted from the decomposition of the hydration products and the oxidation of steel fibers.