粉煤灰对水泥浆体的电阻率与化学收缩的影响

Effect of Fly Ash on Electrical Resistivity and Chemical Shrinkage of Cement Pastes

研究了粉煤灰掺量分别为0、20%和40%,水胶比为0.4的水泥浆体的抗压强度、电阻率、化学收缩以及水化产物的变化规律。电阻率采用无电极电阻率法进行测试,化学收缩采用ASTM C1608-12规定的膨胀测定法进行测试。结果表明,在250 d龄期时,粉煤灰掺量为20%的硬化水泥浆体抗压强度仅比空白组低5%;当粉煤灰掺量增大时,水泥浆体在3 d龄期时的强度、电阻率和化学收缩均减小,抗压强度与电阻率之间具有很好的线性关系。XRD及热重分析表明,随着粉煤灰掺量增加,水化硅酸钙含量减少,在3 d龄期时水化产物中出现了钙矾石。

The evolution of compressive strength, electrical resistivity, chemical shrinkage and hydration products of the cement pastes with fly ash were investigated. The water to binder ratio of the cement pastes were 0.4, and the content of fly ash was 0% , 20% and 40% in mass, respectively. The electrical resistivity was measured by a non-electrode resistivity apparatus. The chemical shrinkage was tested according to ASTM C1608-12. The results show that the compressive strength of the sample with 20% fly ash is just less than that of the control by 5% at the age of 250 d. The compressive strength, electrical resistivity and chemical shrinkage are all decreased at the age of 3 d with the increase of fly ash. The relationship between compressive strength and electrical resistivity at 3 d appears to linear. Among the hydration products, the amount of C-S-H gel is reduced with the incorporation of fly ash. But ettringite could be detected by the XRD and TG analyses at the age of 3 d.