磷酸盐无机胶粘贴碳纤维布加固混凝土结构的工作性能研究

Fiber reinforced polymers (FRP) have been widely used for retrofitting and strengthening concrete structures. However, the epoxy or other organic adhesive commonly used in the current FRP system has some adverse effects such as low softening points under high temperature, emission of toxic fumes, and ease to failure in hydrothermal environment, etc., which greatly limit the scope of FRP applications. This project proposes to use phosphate cement as an alternative adhesive in FRP system. The setting time control of the phosphate cement, excitation mechanism against the fly ash and the optimum mixture ratio will be studied. The appropriate method of surface treatment is explored to improve the wettability between phosphate cement and carbon fiber, and then the microstructure in interfacial zone is investigated. The failure mechanism of the debonding of carbon fiber sheet and pasted concrete incorporated with phosphate cement as the bonding agent under shear are compared with organic adhesive. Based on analysis of the affecting factors of shear capacity, the strength of the strengthened joint is predicted. Furthermore, the performance of this phosphate cement under high temperature is tested. This study will not only develop a safe, reliable and high temperature resistant inorganic phosphate material, but also provide a guidance for the construction process, which enlarges the scope of the application of FRP in the aggressive working environments.

纤维增强型塑料(FRP)在混凝土结构补强加固中得到了广泛的应用。然而目前粘贴碳纤维布所普遍使用的有机胶受热易软化，有毒性，在湿热环境中易失效等问题，限制了FRP技术的应用范围。本项目采用磷酸盐水泥胶凝材料代替有机胶，研究控制磷酸盐水泥凝结时间的方法，明确磷酸盐水泥对粉煤灰的激发机理，确定磷酸盐无机胶的最优配合比；探索改进磷酸盐水泥与碳纤维布浸润性的表面处理方法，分析界面过渡区的显微结构差异，对比无机胶和有机胶在混凝土表面粘贴碳纤维布的剪切失效模式，分析影响承载力的因素，提出粘结强度的估算方法，并掌握磷酸盐无机胶的抗高温性能。本研究将不仅研发一种安全，可靠，耐高温性能好的磷酸盐无机胶凝材料，并为其施工工艺提供指导，扩大碳纤维加固技术的使用范围，使其能够应用于恶劣的工作环境。

本项目通过对磷酸盐胶凝材料作为无机胶加固混凝土结构的性能试验，发现常温下磷酸盐水泥用于加固胶其快干、早强的特性并不能充分的发挥，且性能相对不稳定。随后，将胶凝材料聚焦于硅酸盐水泥，通过试验调整配合比，粉煤灰的掺量，对其与碳纤维布进行表面处理，进行加固混凝土试块稳态和瞬态升温单剪试验。温度范围从20℃到700℃，获得了高温下的破坏模式和最终承载力。从试验结果表明，当温度升至150℃，环氧树脂为代表的有机胶加固节点出现显著的强度下降。然而，用硅酸盐水泥作为无机胶的加固性能在温度到达600℃前并没有明显的减少。证明本项目所采用的以硅酸盐无机胶凝材料，试验配比，施工工艺达到了本项目预期的效果，可以用于高温工作环境。