粉煤灰及养护龄期对湿拌砂浆性能的影响

Effect of Fly Ash and Curing Age on Performance of Wet-Mixed Mortar

以粉煤灰取代部分水泥,研究其掺量及养护龄期对保水率、收缩率、稠度、粘接强度和力学性能的影响,并利用X射线荧光光谱分析仪（XRF）和扫描电子显微镜（SEM）对粉煤灰的物理化学性质进行分析。试验结果表明：掺量在0%~40%,随着粉煤灰掺量的增加,湿拌砂浆干缩率呈减小趋势,湿拌砂浆保水率呈减小趋势。粉煤灰的掺入量与湿拌砂浆拌合物的稠度正比例关系,随着粉煤灰掺量的增加而增大。湿拌砂浆14 d粘接强度随着粉煤灰掺量的增加呈下降趋势。在试验室条件下,掺粉煤灰砂浆试块抗压强度随着养护时间的增长不断增大。因此,在湿拌砂浆中掺入低于30%的粉煤灰时,可以在满足湿拌砂浆力学性能的前提下,抑制收缩变形,提高粘接强度。

Fly ash is used as a partial replacement for cement. The authors studied the effect of the curing age and percentage of fly ash replacement on consistency, shrinkage rate, bonding strength, compressive resistance and mechanical properties of mortar. The chemicalcomposition and microscopic structure of fly ash were tested by X ray fluorescence spectrum analyzer （XRF） and scanning electron microscope （SEM）. The result shows that for the 0%-40% fly ash replacement, as more fly ash is added, Fly ash reduces the dry shrinkage of wet-mixed mortar, reduce water retention rate of wet-mixed mortar. The consistency of wet-mixed mortar is proportional mixing amount of fly ash, Increases with the increase of the amount of fly ash. The 14 d bonding strength of wet-mixed mortar with the increase of fly ash content decreased. The compressive strength of mixing fly ash mortar block increased as the growth of the curing time in the laboratory conditions. Therefore, mixed with less than 30% of fly ash in the wet mortar, the shrinkage deformation of the mortar can be prevented and the bonding strength of the mortar can be improved.