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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。
The influence of temperature on the resistivity of cement hydration was studied, and the hyperbolic equation for estimating the maximum of resistivity was established. It was proposed that the activation energy of pore fluid (E_ (as)) can be calculated according to the resistivity at different temperatures. And activation energy (E_ (ar)) of hydration reaction. The cement-water samples used in the test had water-cement ratios of 0.30, 0.35, 0.40, 0.45 and 0.55, respectively. The curing temperatures were 15, 20 and 30 ℃, respectively, and the test time was 72h. In order to eliminate the influence of temperature on ion migration of pore liquid phase, the resistivity values measured at 15 ℃ and 30 ℃ were respectively calibrated at 20 ℃. The influence of temperature on the hydration of cement was analyzed. The results show that the E_ (as) increases from 16.5 kJ / mol to 25.7 kJ / mol when the water-cement ratio decreases from 0.55 to 0.30, because the liquid-phase ion concentration of the cement with low water-cement ratio is larger. The calculation shows that the activation energy E_ (ar) of Portland cement hydration reaction is 37.2 kJ / mol, which is close to the recommended value of ASTM C1074 (40 kJ / mol). The hyperbolic equations of resistivity obtained at different curing temperatures show that the lower the temperature, the greater the maximum value of the resistivity over the temperature range tested.