水泥浆体的显微图像和质量随时间变化的测量与分析

The Microscopic Image of Cement Paste and Quality Measurement and Analysis of Change with Time

用光学显微镜和电子天平相结合的方法,在室温(约290K)、1个大气压、相对湿度约45%的条件下,对水泥浆体的显微图像和质量进行了实时的测量.结果表明,水泥的水化反应可以划分为4个过程:1)0至1t(=8.3min)的I过程,水泥浆体的约化亮度Is随t近似线性增加,同时约化质量m随t线性减小;2)1t至2t(=27.9min)的II过程,Is随t快速近似线性增加,同时m随t线性减小;3)2t至3t(=46.3min)的III过程,随时间t的增加,m先快速、然后缓慢下降到稳定值,Is几乎不变;4)3t以后的VI过程,m和Is不随t变化.水泥浆体质量减少是因为其中水的挥发,其颜色变淡是因为其中CH的形成.1t之前CH的形成率较低,而1t至2t是CH形成率较快的时期,2t之后已经基本没有CH形成.因此,1t、2t分别表征的是诱导期、加速期的结束.从2t至3t时期,浆体中水仍有少量挥发,但已经不再有CH的生成.3t以后,浆体水分挥发得极少,也不再有CH的生成.

Integrating light microscope with electronic balance, the microscopic image and mass of the cement paste were measured in real-time under one bar pressure and 45%RH （relative humidity） at room temperature （about 290K）. The result shows that hydration reactions of the cement can be divided into four processes： 1） process-I appears from 0 to t 1 （=8.3min） where the reduced luminance （I） of the cement pastes increases, while the reduced mass （m） decreases with time;2） process-II starts from t1 to t2 （=8.3min）, and during which I goes up rapidly meanwhile m declines with time; 3） process-III emerges between t2 to t3 （=27.9min） where m drops first rapidly and then slowly to a steady value, but I almost keeps constant with time;4） process-IV arises after t3, and both I and m do not vary with time. Combining the knowledge about hydration reaction of cement with the author’s some new ideas, it was proposed that I originates from evaporation of the water, while the fading color results in the form of Ca（OH） 2 （CH）. In the process-I, the formation of CH is at low rate, but the formation rate comes faster during the process-II, and there is no formation of CH after the process-II. So, t1 and t2 expresses, respectively, the end of the initial period and acceleration period. From t2 to t3, a little water of cement still volatilizes, but no CH generates. There is little water to volatilize and CH also does not form after t3.