粉煤灰掺量对硬化水泥净浆长期溶蚀性能的影响

Effect of Fly Ash Content on Long-term Leaching Performance of Hardened Cement Paste

为了分析长期处于软水环境下粉煤灰对水泥基材料溶蚀特性及其溶蚀过程的影响,以单掺粉煤灰的复合水泥浆体薄片试件为研究对象,开展不同粉煤灰掺量的水泥复合浆体浸泡在去离子水长达两年的溶蚀实验,并通过饱水-干燥称重、SEM/EDS、XRD等测试,分析溶蚀过程中复合水泥浆体薄片试件的孔隙率、微观结构、钙硅比及物相组成等参数的变化规律,揭示粉煤灰对水泥浆体溶蚀特性的影响及其抗溶蚀性能的改善机理。结果表明,在水泥浆体中合理掺加粉煤灰可有效地改善其微观结构及物相组成,减缓水泥浆体的微观结构劣化和溶蚀进程,提高其在去离子水中的抗溶蚀性能,掺入40%粉煤灰的复合水泥浆体在去离子水中具有最佳的抗溶蚀性能。

In order to analyze the effect of fly ash on the leaching characteristics and leaching process of cement-based materials in a long-term soft water environment,the cement paste sheet specimens with fly ash singly were used as the research objects,and the two-year routine leaching experiments of binary cement pastes with different content of fly ash were carried out.By using saturation-drying weighing,scanning electron microscopy(SEM/EDS)and X-ray diffraction analysis(XRD)tests,the change of porosity,microstructure,calcium-silicon ratio(Ca/Si)and phase composition were investigated to analyze the effect of fly ash on leaching characteristics of cement paste and its improvement mechanism on leaching resistance.Results show that,the addition of fly ash with appropriate content in cement paste improves its microstructure and phase composition,slows down its microstructural deterioration and leaching process,and effectively improves its leaching resistance in deionized water.The cement paste with 40%fly ash has an optimum leaching resistance exposed in deionized water.