不同温度下水泥基材料水化行为的电阻率监测及热力学模型研究

The electrical resistivity method based on a non-contact electrical resistivity measurement apparatus can be employed to investigate the hydration behavior of cement-based materials and become progressively popular. The evolution of electrical resistivity can be used to monitor the macroscopic properties of cement-based materials and determine the microstructure development and the transformation of hydration products. The thermodynamic modelling of the hydration of cement-based materials can also be used for predicting the influence of environment on the hydrate assemblage and thus the evolution of properties..The electrical resistivity measurement was performed with heat release, chemical shrinkage, hydration product, pore solution and pore structure analyses in this study. The electrical resistivity method was proposed to monitor the hydration behavior of cement-based materials at different temperatures. The electrical resistivity of the cement-based materials can be measured accurately by improving the sample mould of the non-contact electrical resistivity measurement apparatus. The activation energy of the hydration of cement-based materials can be calculated by the electrical resistivity and chemical shrinkage at different temperatures. Therefore, the strength of cement-based materials can be estimated by the maturity method. Finally, the thermodynamic modelling of the hydration of cement-based materials at different temperatures can be established by using the CEMDATA database and the GEM software. The evolution of microstructure and properties as well as the service behavior and performance adjustment of cement-based materials can be predicted according to the thermodynamic modelling.

基于无电极电阻率测定仪的电阻率法可用于研究水泥的水化机理，判断微结构的变化和水化产物的转变以及宏观性能的发展过程，目前已在水泥基材料研究中逐渐推广。水泥基材料水化过程的热力学模型则能预测不同环境作用下水化产物组成与材料性能的演变规律。.本项目综合采用电阻率法、量热法和化学收缩测试，并结合水化产物、孔溶液和孔结构分析结果，通过改进现有的样品模具，更准确地测试不同温度下水泥基材料的电阻率，建立不同温度下基于电阻率法的水泥基材料水化行为的监测机制。根据不同温度下的电阻率与化学收缩计算水泥基材料水化反应的活化能，基于成熟度法预测水泥基材料的强度。最后采用CEMDATA数据库和GEM软件建立不同温度下水泥基材料水化过程的热力学模型，根据热力学模型判断水泥基材料的微结构及其性能演变规律，进而预测水泥基材料在不同温度下的服役性能及其调控机制。

基于无电极电阻率测定仪的电阻率法可用于研究水泥的水化机理，判断微结构的变化、水化产物的转变以及宏观性能的发展过程，目前已在水泥基材料研究中逐渐推广。本项目研制了一种适用于无电极电阻率测定仪的控温装置，能够准确测试不同温度下水泥基材料的电阻率。完成了不同温度下粉煤灰与硅酸盐水泥复合体系的电阻率测试，分析了孔溶液离子浓度和孔结构对电阻率的影响机理。建立了铝酸盐水泥水化行为的电阻率监测机制，采用电阻率法研究了硅灰对铝酸盐水泥水化行为的影响机理。完成了不同温度下硫铝酸盐水泥水化时的水化热、化学收缩测试，计算出了硫铝酸盐水泥水化反应的表观活化能，分析了不同矿物掺合料对硫铝酸盐水泥水化行为的影响机理。研究表明，在水化初期和72 h时，由于孔溶液离子浓度和孔结构的综合作用，粉煤灰对硅酸盐水泥浆体电阻率的影响规律相反。铝酸盐水泥水化时的电阻率变化曲线能够反映其晶相转变过程，掺入硅灰有助于抑制水化产物的晶相转变，进而有助于解决强度倒缩问题。硫铝酸盐水泥水化反应的表观活化能计算结果与水化参数和计算方法相关。在适当掺量下，掺入粉煤灰、硅灰、矿渣粉和钢渣粉有助于改善硫铝酸盐水泥的微结构和性能。本项目扩展了电阻率法在水泥基材料研究中的应用范畴，提供了监测水泥基材料水化行为及性能演变的新思路。