电阻率法测定硅酸盐水泥水化活化能  

Activation Energy of Portland Cement Hydration by Electrical Resistivity Measurement

作　　者：魏小胜[1] 肖莲珍[2] 

机构地区：[1]华中科技大学土木工程与力学学院,武汉430074 [2]武汉工程大学材料科学与工程学院,武汉430073

出　　处：《硅酸盐学报》2011年第4期676-681,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(50778078)资助项目

摘　　要：研究了温度对水泥水化时电阻率的影响情况,建立了用于估算电阻率极大值的双曲线方程,提出根据不同温度时的电阻率可以计算孔隙液相活化能(E_(as))和水化反应的活化能(E_(ar))。试验所用水泥浆体试样的水灰比分别为0.30、0.35、0.40、0.45和0.55,养护温度分别为15、20℃和30℃,测试时间均为72h。为消除温度对孔隙液相离子迁移的影响,在15℃和30℃测得的电阻率值分别以20℃为基准进行了校正,分析了温度对水泥水化产物形成的影响。研究表明:当水灰比从0.55减小到0.30时,E_(as)从16.5kJ/mol增大到25.7kJ/mol,这是因为低水灰比水泥浆体的液相离子浓度较大。计算表明:硅酸盐水泥水化反应的活化能E_(ar)为37.2kJ/mol,这与ASTM C1074的推荐值(40kJ/mol)比较接近。在不同养护温度下得到的电阻率双曲线方程表明:在所测试的温度范围内,温度越低,电阻率的极大值越大。Temperature effect on the electrical resistivity of Portland cement pastes during first 72 h was investigated.The experiments were conducted on the cement pastes with various water cement ratios of 0.30,0.35,0.40,0.45,0.55 at different curing temperatures of 15,20 and 30℃.The hyperbolic equation for each sample was established to estimate the ultimate resistivity.The electrical resistivity at various temperatures can determinate the activation energy for the liquid solution in pores（E_（as）） and the activation energy for hydration reaction（E_（ar））.The electrical resistivities at 15 and 30℃are obtained based on the value at 20℃to eliminate the effect of temperature on the ionic mobility in the liquid solutions.The E_（as） increased with the decrease of water cement ratio due to a higher ion concentration in a lower water cement ratio paste solution,and the E_（as） ranged from 16.5 to 25.7kJ/mol.The activation energy of cement hydration determined was 37.2kJ/mol,which was similar to the value recommended by the ASTM 1074 standard method.A lower curing temperature could give a higher ultimate resistivity in the measured temperature region of the paste.

关 键 词：电阻率 水泥水化 活化能 温度 

分 类 号：TQ178[化学工程—硅酸盐工业]