表面改性粉煤灰对水泥浆体强度和自收缩的影响

Effects of Surface Modified Fly Ash on Strength and Autogenous Shrinkage of Cement Pastes

在生石灰激发下,采用水热-煅烧处理对粉煤灰进行表面改性,利用X射线衍射、扫描电镜和能谱分析等测试方法对表面改性粉煤灰的物相结构和化学组成进行了表征,并采用背散射扫描电镜和压汞仪研究了掺表面改性粉煤灰水泥浆体的微观结构。试验测定了掺表面改性粉煤灰的硅酸盐水泥浆体的抗压强度、自收缩和孔隙率。结果表明,表面改性粉煤灰颗粒表面生成了具有水化活性的β-C2S,其水化产生凝胶,明显改善了复合水泥浆体中粉煤灰颗粒与水泥基体的界面,降低了复合水泥浆体的孔隙率和自收缩,提高了掺表面改性粉煤灰复合水泥浆体的早期强度。

The surface of fly ash particles is modified by the hydrothermal-calcination treatment method via the addition of quick lime. The mineral phases and chemical compositions of the modified fly ash are analyzed by X-ray diffraction and scanning electron microscope equipped with energy dispersive spectroscopy, and the micvostrueture of cement pastes with the modified fly ash are studied by the backscattered electron microscope and mercury porosimeter. The effects of the modified fly ash on compressive strength, autogenous shrinkage and porosity of the composite cement pastes are investigated. The results show that 13-C2S phase is formed on the surface of the modified fly ash particles. Due to the hydration of the 13-C2S, which can obviously improve the interface between the fly ash particles and the cement basis of the composite cement pastes, the porosity and autogenous shrinkage of the composite cement pastes are decreased, and the early strength of the composite cement pastes with the modified fly ash is improved.