轻烧氧化镁膨胀剂膨胀性能的温度敏感性及其机理分析

Temperature sensitivity of light calcined magnesia expansion agent and its mechanism analysis

为了考察温度对轻烧氧化镁膨胀剂膨胀性能的影响,选取了2种典型煅烧活性的轻烧氧化镁,研究了氧化镁水化速率及掺加氧化镁浆体变形性能的温度敏感性,并从氧化镁水化动力学角度对其机理进行分析.试验结果表明:低活性轻烧氧化镁的水化及膨胀速率显著依赖反应温度,表现出较强的温度敏感性;轻烧氧化镁的水化过程同样可以划分为和硅酸盐水泥相近的5个阶段,试验所采用的2种氧化镁在水化反应诱导期及加速期的活化能(分别为75.9和149.8 kJ/mol)差异最为显著.氧化镁膨胀剂自身膨胀效能及水化反应动力学参数的差异是造成温度敏感性差异的主要原因.

To evaluate the effect of temperature on expansion of light calcined magnesia expansion agent（MEA）,two typical MEA were chosen,and temperature sensitivity of hydration rate of MEA and expansive process of cement paste containing MEA were analyzed.Furthermore,the mechanism of temperature was also discussed based on hydration kinetics of MEA.The results indicate that the hydration and expansion of MEA calcined at higher temperature show stronger temperature sensitivity compared to that calcined at lower temperature.Similar to Portland cement,the hydration process of MEA can also be divided into five stages,and the activation energy difference in induction and acceleration period of hydration reaction is remarkable（75.9 and 149.8 kJ/mol,for two MEA respectively）.The differences of expansive effectiveness and kinetic parameters are the main cause of the difference of temperature sensitivity.