Experimental Study On UV Durability Of Fiber Reinforced Polymer Strengthened Concrete Structure

With fiber reinforced polymer (FRP) widely used in the reinforcement of concrete structural, its durability has also attracted more and more attention of domestic and foreign scholars, engineers and researchers. However, the current study for FRP is mostly about freeze-thaw resistance, resistance to the corrosive solution, carbonation etc. While as a plastic material, the resistance of the FRP to UV aging properties is very important but few studies, the existing experimental study results are difficult to play a guiding role in the actual project. In view of the previous studies, this treatise made a systematic study on the UV durability of FRP strengthened concrete structure. The main researches are as follows:Ⅰ. The UV durability of FRP sheets are carried out at the following parameters: the types of FRP (carbon fiber, glass fiber and basalt fiber), the layers of FRP, the types of the impregnating resin, and the days of the test, etc. The results showed that:1) different types of fiber materials showing different UV durability. The carbon fiber is better, and the basalt fiber is poor.2) Layers to change the UV durability of fiber reinforced composite materials can have little effect.3) The types of impregnating resin take a great impact on FRP materials. The impregnating resin which had higher early strength has not necessarily better durability.3) After UV aging, FRP strength may be increased which reasons may be that the epoxy resin curing again or the uneven distribution of surface thermal stress.Ⅱ. The study on UV durability of different strength concrete:Analyzed the structure and composition of the concrete after UV irradiation by means of SEM, XRD. The results show that:the strength of different strength grade concrete after UV irradiation showed an increase trend, which result is same as SEM and XRD. The environment in the UV aging chamber may be beneficial effects on concrete, which is hot and humid.Ⅲ. Studied the changes in the impregnating resin strength and elastic modulus after UV aging, discussed the impact of impregnated resin durability of the fiber material. The results show that:Different impregnating resins have different UV durability. Some impregnated resin begins performance dropped significantly in the early irradiated, and the others not. By the resin affect the performance of FRP sheet is also a downward trend, but the decline of the performance of the sheet is less than the impregnated resin performance decline.IV. Do tests on FRP materials and concrete bonding properties, which including different FRP types, different FRP layers, different strength grade of concrete, different bond length and different UV cycle irradiation time. The results show that: The bonding properties of carbon fibers and concrete are better and of more durable. The bonding properties of S-glass fibers and basalt fibers are secondary, while E-glass fibers are worst. The durability of basalt fibers is weakest. Increased number of layers can significantly improve the bonding properties and UV durability. Improve the strength of concrete can improve the bonding properties, but less effect on the UV durability. There are not significant differences between different bond length specimens. Considering the various factors, that the UV durability of the bonded between FRP and concrete is first decreased and then rebounded. The general decline is small.V. To propose measures to improve the UV durability of FRP strengthened concrete structures, are:1) imposed the structure by the surface protection, such as paint, mortar surface.2) Increased FRP paste layers.3) Improve the impregnating resin.4) Do surface treatment on concrete which were reinforced by FRP.