养护方式对碱激发矿渣/粉煤灰胶凝材料抗压强度影响研究

Effect of Curing Methods on Compressive Strength of Alkali-activated Slag/Fly AshComposite Cementitious Materials

本工作主要研究了不同粉煤灰掺量的碱激发矿渣/粉煤灰复合胶凝材料(AASF)分别在标准养护、烘箱养护及微波养护下强度发展规律,并通过水化产物和微结构的演化就强度发展进行机理分析。采用X射线衍射(XRD)、热重-差示扫描热分析(TG-DSC)、扫描电子显微镜(SEM)等技术手段对水化产物微观结构进行了系统研究。结果表明:热养护能显著提高胶凝材料的前期水化反应,促进C(N)-S(A)-H凝胶的生成。对比标准养护1 d强度,经烘箱养护和微波养护后的AASF试样强度分别提升了144%~531%、184.4%~385.5%。相较于烘箱养护,绝大多数情况下微波养护具有更大的优势。随着粉煤灰掺量提高,标养试样各龄期强度均持续降低。而20%、40%的粉煤灰掺量分别对微波养护及烘箱养护试样抗压强度发展有积极的影响。

Compressive strength of alkali activated slag/fly ash composite cementitious materials with different fly ash replacements was studied in this paper,where standard curing,oven curing and microwave curing were applied to cure the paste specimens,respectively.Evolution of hydration products and microstructure of the specimens was also analyzed to deeply understand the strength development.It was found that thermal curing(oven curing and microwave curing)has dramatically improved compressive strength of the composite system at an early age as a result of an effective activation of fly ash under heating.This is in particular for the specimens cured by microwave.However,due to uneven heating induced cracking,a strength decline in a long term has occurred on the specimens cured in oven.Thermal curing has greatly increased the replacement of fly ash in the composite system.Due to the synergy between slag and fly ash,when the replacement of fly ash varied within 60%,strength of the specimens could generally keep constant in the case of oven curing and could be even higher than the pure slag ones in the case of microwave curing.