Durability Investigation of Carbon Fiber Reinforced Concrete under Salt-Freeze Coupling Effect

Abstract

In order to study the durability behavior of CFRP (carbon fiber reinforced polymer) reinforced concrete, three category specimens (plain, partially reinforced, and fully reinforced) were selected to investigate its performance variation concerning chlorine salt and salt-freeze coupled environment, which included the microscopic examination, the distribution of chloride ion concentration, and the compressive properties. By observing the microscopic of the specimens, the surface and cross-section corrosion deterioration was examined with increasing exposure time, and the physical behavior of CFRP and core concrete were discussed. The chloride ion diffusion test exerted that the chloride ion concentration in plain specimens is at least 200 times higher than that of fully reinforced specimens. Therefore, the effectiveness of CFRP reinforcement will be proved to effectively hinder the penetration of chloride ions into the core section. The formula of the time-dependent effect of concrete diffusivity with salt-freeze coupling effect was presented and its accuracy verified. A time-varying finite element model of chloride ion distribution was established by using ABAQUS software. It can be seen from the axial compression test that the strength loss rate of three categories of specimens was varied when subjected to the corrosion environment. Therefore, it is proved that CFRP reinforcement can effectively reduce the deterioration of the specimen’s mechanical properties caused by the exposure environment. The research results can provide technical reference for applying the CFRP strengthened concrete in a severe salt-freeze environment.

Durability Investigation on CFRP Strengthened Cementitious Materials in Cold Region

“…In addition, pore water continuously repeats the process of crystallization–liquefaction–crystallization under the effect of the freeze–thaw cycle. As a result, the inner crystals continuously produce frost heaving force and finally lead to the micro-cracks constantly produced under the repeated action of frost heaving force [ 6 ]. It indicates that the damage to specimens in a salt-freeze coupling environment is more severe than that in a chloride salt immersion environment.…”

“…However, most researchers only discussed the durability of the above objects in a single chloride salt immersion environment or a single freezing-thawing environment. Therefore, limited research focus on a comprehensive study of the coupling effect of influencing factors [ 6 ].…”

Sulfate erosion investigation on FRP-confined concrete in cold region

“…The silicate in the concrete combines with the hydrogen ions in the water to form silicic acid, and the remaining OH − causes the pH of the saturated solution to increase. The pH changes are more significant in 0–25 freeze–thaw cycles, and the changes are not apparent in 25–100 freeze–thaw cycles 30 . However, it is found here that the pH continued to increase over 25–100 freeze–thaw cycles.…”