Study On Hygrothermal Ageing And Elevated Temperature Performances Of Basalt Fiber Reinforced Epoxy Composites

Fiber reinforced plastic(FRP)composites are considered to be an effective way to solve the problem of steel corrosion, due to it's excellent mechanical properties and corrosion resistance behavior. FRP have been attracting more and more attention in the world. However, due to the durability of macromolecule composite materials has not been studied as systematical as metallic materials, Besides, the high temperature performance of the resin matrix is poor,and the FRP corrosion theory and database of high-temperature performances are not well developed, Wide application of FRP in civil engineering is blocked.In this paper, acceleration test is used to study the long-term durability of unidirectional basalt fiber reinforced epoxy (BFRP) wet lay-ups soaked in distilled water and alkaline solution. The variations of tensile strength, tensile modulus, elongation, microstructure, glass transition temperature as well as microhardness of BFRP with soaking time were investigated. The results show that, the water diffusion processes in BFRP wet layups soaked in distilled water and alkaline solution for 1.5 years, follow the two-stage model and Langmuir model. The maximum water absorption increased with the soaking temperature and immersion time. The degradation of the resin matrix, fiber/resin interface debonding, fiber etched destruction are responsible for the decrease of the tensile strength.Because the resin matrix is flammable, soften and thermal degradation at elevated temperatures, the safety design of FRP and strengthened structures under high temperature is critical when applied in civil engineering. In view of this, unidirectional basalt fiber fabric reinforced epoxy wet lay-ups were studied on the tensile strength and glass transition temperature at high temperatures and after various period treatment at high temperatures. As found, when the temperature exceeds the glass transition temperature of FRP, the tensile strength decreased dramatically, and then leveling off as the temperature increased by 350°C, The final strength tendsed to its half values. Besides, the relative tensile modulus decreased with increasing temperature linearly. After high temperature treatment for various temperatures (up to 72 hours), the mechanical properties at room temperature of BFRP wet layups have been restored mostly. A linear relationship of the tensile strength and the weight loss was observed.