定形相变材料的制备及对混凝土耐高温性能的影响

The Preparation of Stationary Phase Transition Materials and Its Effect on the High Temperature Resistance of Concrete

为了提高混凝土结构的耐高温性能,从混凝土自身的储热性能出发,制备了一种定形相变材料,并研究了该相变材料对混凝土导热性能和高温后力学强度的影响。结果显示:硫酸铝铵掺量越高,相变材料的相变焓越大,当其掺量超过70%时,差示扫描量热法(DSC)特征参数趋于稳定;定形相变材料具有较好的热稳定性,且高温下硫酸铝铵和SiO2并未发生化学反应;相变材料的加入能提高混凝土的储能密度,降低其导热系数,混凝土内部的温度随相变材料掺量的增多而逐渐降低;当相变材料掺量小于6.5%时,相变材料的加入能明显提高混凝土高温后的强度,而当相变材料掺量大于6.5%时,再提高其掺量对混凝土耐高温性能的改善作用有限。

In order to improve the high temperature performance of concrete structure,a stationary phase transition material based on the heat storage properties of concrete was prepared,and the influence of phase transition material on thermal properties and mechanical strength after high temperature were studied.The results show that the higher the content of NH4Al(SO4)2·12H2O,the greater the phase transition enthalpy of the phase transition material.When the amount of admixture exceeds 70%,the DSC characteristic parameters tend to be stable.The stationary phase transition material has good thermal stability,and there is no chemical reaction between NH4Al(SO4)2·12H2O and SiO2 at high temperatures.The addition of phase transition materials can increase the energy storage density of concrete,and reduce its thermal conductivity.The temperature inside of the concrete gradually decreases with the increase of the amount of phase transition materials.When the amount of phase change material is less than 6.5%,the addition of phase change material can obviously increase the strength of the concrete after high temperature.When the amount of phase change material is greater than 6.5%,the effect of the amount of phase change material on the high temperature resistance of concrete is limited.