升温条件下偏高岭土基地质聚合物粘结剂的粘结性能研究

结构加固中应用的环氧树脂等有机粘结剂的耐高温性不足,升温条件下易丧失力学性能导致结构失效。本文以偏高岭土基地聚物作为无机粘结剂,通过不同温度下的钢-钢拉伸剪切试验和表层嵌贴CFRP-混凝土拔出试验,考察地聚物粘结剂在升温条件下的粘结性能变化规律。试验结果表明:在常温环境下,树脂粘结剂的粘结性能优于地质聚合物粘结剂的粘结性能;但在本文试验设置的升温条件下,树脂粘结剂试件的粘结承载力明显下降,而地质聚合物粘结剂试件的粘结承载力则基本不受温度变化的影响。对粘结界面的粘结滑移本构关系的分析表明,随着温度升高,树脂粘结剂的最大粘结应力逐渐降低,其对应的滑移量也有所增大;与之相比,地聚物粘结剂的最大粘结应力及滑移均未随温度升高发生显著变化,证明了地聚物粘结剂的粘结性能对本文试验温度不敏感。这表明地质聚合物具有较好的耐高温性能,有发展无机粘结剂的潜力。

On the Bonding Performance of Metakaolin-based Geopolymer Adhesive under Heating Condition

Epoxy resin and other organic adhesives used in structural reinforcement have not enough high temperature resistance and are easy to lose mechanical properties under heating condition resulting in structural failure. In this paper, metakaolin-based goepolymer was used as inorganic adhesive, the tensile shear experiment for steel-steel structure and the pull-out experiment for steel with carbon fiber reinforced polymer (CFRP) mounted on surface-concrete structure were carried out respectively, to study the bonding performance variation of metakaolin-based goepolymer adhesive under heating condition. Experimental results show that in room temperature environment, the bonding capacity of epoxy resin is better than that of geopolymer adhesive; however under heating condition, the bonding capacity of epoxy resin decreases significantly, while the bonding capacity of specimen bonded with geopolymer adhesive is not affected by temperature variation. Moreover, the analysis of bonded interface bond-slip constitutive relation indicates that the maximum bonding stress of epoxy resin decreases gradually and corresponding slip volume increases with the temperature increase. In contrast, the maximum bonding stress and slip volume of geopolymer adhesive change not so obviously. This confirms that the metakaolin-based goepolymer has a better high temperature resistance, and is potential to be used as adhesive in structures strengthening.