Study On The Pultrusion Process Of CFRP Plate And Its Hygrothermal Durability

Carbon fiber reinforced polymer (CFRP) composites, as a new structuralmaterial, possess excellent mechanical properties and corrosion resistance. In recentyears, FRPs have been widely used in reinforcing and upgrading of infrastructures,such as civil engineering structures, reinforced concrete bridge decks, highway, etc.This paper studied the effects of pultrusion processing parameters on the mechanicalproperties of CFRP plates. Taguchi method was used to optimize those pultrusionparameters. In the following, the long term durability of CFRP plates immersed indistilled water and strong alkaline solution were investigated.According to Taguchi method, the effects of pultrusion parameters wereestimated quantitively on the mechanical properties of CFRP plates. The resultsindicate that the epoxy type and fiber content exhibits the maximum effects on themechanical properties of the CFRP plates, which give the contribution of variationabout36.7%and40.5%, respectively. Pultrusion speed, mold temperature,post-curing temperature and the pretension force also exhibit significant effects onthe mechanical property of CFRP plates, but to a much reduced degree, and theeffects of the temperature of resin bath is ignored. The CFRP plates produced withthe optimized pultrusion parameters have the tensile strength and modulus about2.5GPa and172.8GPa.Water uptake, bending and tension properties of CFRP plates exposed to waterand alkaline solution were investigated. As found, exposed to lower temperaturemedia, water uptake curves of CFRP plates follows the classic Fick’s law, and themechanical properties are less affected exposed to low temperature media (i.e. less40℃). At higher temperature (60℃and80℃), the water uptake curves deflectsfrom the classic Fick’s law, and the mechanical properties were reducedsignificantly. Compared to distilled water, the alkaline solution shows more adverseeffects on the degradation of the CFRP plates. Hydrolysis of the resin matrix isattributed to the deteriorated durability of CFRP plates.According to Arrhenius model, the deterioration of mechanical properties ofCFRP plates exposed to water and alkaline solution at room temperature is predicted.The results show that retention tensile strength of CFRP plate exposed to water andalkaline solution at room temperature are predicted to be83.3%and79.8%after200years service, respectively.