粉煤灰对纤维增强砂浆韧性及微观结构影响研究

Study on the Effect of Fly Ash on the Ductility and Microstructure of Fiber Reinforced Mortar

文中采用抗折试验、抗压试验以及四点抗弯试验研究粉煤灰掺量对纤维增强砂浆力学强度和弯曲韧性的影响规律,并通过热重分析、压汞法以及扫描电子显微镜分析粉煤灰对纤维增强砂浆水化程度、孔隙结构以及微观形貌的影响。结果表明:提高粉煤灰掺量会降低抗折强度;粉煤灰的掺入降低了早期基体强度和基体与纤维之间的粘结强度,提高弯曲韧性、提高粉煤灰掺量会减小水化产物的含量;粉煤灰的掺入导致早期砂浆孔容和有害孔体积增大,但是有利于细化后期孔结构;粉煤灰的掺入有利于减小凝胶体与纤维之间的有效接触面积,降低物理摩擦。

The flexural test,compressive test and four-point bending test were used to study the effect of FA dosing on the mechanical strength and bending toughness of fiber-reinforced mortar,andt he effect of FA on the hydration degree,pore structure and mcirostructure of fiber-reinforced mortars was analyzed by thermogravimetric anayl sis(TGA),mercury intrusion porosimetry(MIP),and scanning electron microscope(SEM).The results show that:the flexural strength decreased with increasing the dosage of FA;FA decreased the early matr ix strength,and enhanced the bond strength between matrix and fiber.Increasing the dosage of FA reduced the content of hydration products;The pore volume and harmful pore volume at early stage were inrceased by adding FA,while the pore structure was refined at ltae stage.The addition of FA caused the decrease in the contact area between the matrix and the fibers,and reduced the physical friction.