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分别采用水胶比为0.3、0.4和0.5的净浆和砂浆,结合文献模型对水泥基材料中水蒸气的等温吸附(脱附)平衡和动力学过程进行了拟合和参数分析。结果表明:多层吸附的Guggenheim-Andersen-de Boer(GAB)模型能够更好地描述水泥基材料中水蒸气的吸附(脱附)平衡以及吸附-脱附滞回,吸附过程的第1层吸附能常数大于脱附过程的,但单层吸附量小于脱附过程的,吸附-脱附滞回在相对湿度为65%~70%时最大;二阶模型最能够描述水泥基材料中水蒸气的吸附(脱附)动力学过程,二阶模型中的初始吸附速率要明显低于初始脱附速率,两者均随相对湿度的增大而显著增加;速率常数在吸附过程中随相对湿度减小而增大,在脱附过程中则随相对湿度减小而减小。
The pure water and mortar with water / cement ratio of 0.3, 0.4 and 0.5 were respectively used to simulate the isothermal adsorption (desorption) equilibrium and kinetic process of water vapor in cement-based materials. The results show that the multi-layer adsorption Guggenheim-Andersen-de Boer (GAB) model can better describe the adsorption-desorption equilibrium of water vapor in cement-based materials and the adsorption-desorption hysteresis. The adsorption of the first layer The energy of adsorption is greater than that of desorption but the adsorption capacity of monolayer is less than that of desorption. The adsorption-desorption hysteresis is the largest when the relative humidity is 65% -70%. The second-order model can describe the water vapor of cement- Adsorption (desorption) kinetics process, the initial adsorption rate of the second-order model was significantly lower than the initial desorption rate, both with a significant increase in relative humidity; the rate constant decreases with the relative humidity in the adsorption process But increases with decreasing relative humidity during desorption.