碱粉煤灰矿渣混凝土的抗渗性能实验研究

Experimental Study on Impermeability of Alkali Activated Fly Ash-Slag Concrete

抗渗性是混凝土重要的耐久性指标之一。通过对比研究了不同固态分散相组成的碱粉煤灰矿渣混凝土的抗渗性能,并结合X-射线衍射(XRD)、傅立叶转变红外光谱(FT-IR)、扫描电子显微镜(SEM)、压汞法(MIP)对碱粉煤灰矿渣水泥石的物相组成和微观结构进行分析。结果表明:碱矿渣混凝土水化产物主要为低Ca/Si比的(I)C-SH凝胶,体系中随着粉煤灰掺量的增大,水化产物逐渐向聚合度更高的C(N)-A-S-H凝胶结构转变;当粉煤灰掺量不超过30%,粉煤灰能够优化碱粉煤灰矿渣体系孔隙结构,提高碱粉煤灰矿渣混凝土的抗渗性;当粉煤灰掺量大于30%,粉煤灰较低的活性导致水泥石水化产物数量减少,水泥石大孔数量和总孔隙量增大,相应混凝土抗渗性能呈明显下降趋势。

Impermeability is one of the important durability indexes of concrete. In this study,the impermeability of alkali activated fly ash-slag concretewith various ratios of fly ash to slag were investigated. The reaction products and microstructure of alkali activated fly ash-slagpaste（ AFS） were examined by XRD、FT-IR、SEM and MIP. The results show that the hydration products of alkali activated slag are mainly C-S-H gel with low Ca/Si ratio. With the increasement of fly ash,the C-S-H gel gradually changed to C（ N）-A-S-H gel with a higher degree of polymerization. When the dosage of fly ash is less than 30%,which can improve the compactness and impermeability of AFS; When the dosage of fly ash is more than 30%,The reaction products of AFS decreased,which attributed to the low activity of fly ash compared with the slag based specimens,and the compactness and impermeability of alkali activated fly ash-slag Concrete appeared to a declined trend.