Experimental Study On Improvement Of Mechanical And Durability Of GFRP Bars Introduced By Nano Material

Rencently, Fiber Reinforced Plastics(FRP) reinforcement is gaining more popularity in construction in bridges, roads and tunnels. Due to their superior properties, such as high mechanical properties, light-weight, cossorion resistance, FRP bar become one of new alternative materials as a replacement for traditional steel bars. GFRP reinforcement attracted research interest worldwide because of their superior properties and low cost. The lack of data on durability of FRP reinforcements is a major obstacle to their acceptacen on a broader scale in civil engineering. The durability of GFRP reinforcement, especially under sever environmental conditions, is now recognized as the most critical topic of research.It is proved that GFRP bars were subjected to hygrothermal effect and alkaline attack, so we introduced organoclay into polymer matrx to fabricate Nano-GFRP bars aiming at improvement of the durability. The detail works listed as follows:(1) In-situ polymerization method was employed to fabricate unsaturated polyester/organo-montmorillonite(UP/OMMT) nanocomposite. Results showed that introduced OMMT delayed the gelatin and curing. According to characterization of XRD and TEM, the intercalated structure was obtained. At the same time, the thermal stability, strength and ductility performance of nanocomposite were also improved;(2) Compared to neat UP, the barrier performance of 3wt% nanocomposite was improved. Results indicated that in water immersion and absorption tests, the diffusion coefficient was lower than neat UP, and both diffusion process deviated from the Fickian diffusion. In the vapor stable diffusion test, both diffusion coefficient and weight-gain were reduced by 74%.(3) Common GFRP bars and 3wt% GFRP bars were fabricated in the factory condition. The tensile tests results showed that the preparation would lead to more organoclay aggregations and micro-cracks, which lowered tensile strength of Nano-GFRP bars. According to accelerated aging method, both water immersioin and dry/wet cycles tests were employed. The results indicated that the degradation speed of Nano-GFRP bars was reduced, and because of further curing inside, the strength and modulus of Nano-GFRP bars would fluctuated during aging periods.