Influence of high temperatures on the bond between carbon Fibre-Reinforced polymer bars and concrete

Abstract

The effect of corrosion on reinforced concrete structures can lead to significant economic losses. Therefore, steel bars used in the concrete structures must be replaced with a different material that can withstand water contact without causing corrosion and can ensure the safe operation of the structure during its lifespan, even in adverse weather. Carbon-fibre-reinforced polymer (CFRP) bars are one of the materials that can replace steel bars and they have already been applied as a substitute previously. This study analyses the bonding of these bars with concrete at high temperatures and for longer time periods. It presents an experimental plan that involves a series of pullout trials at different ages, days, and thermal conditions in CFRP rods either treated with ribbed steel bars or that underwent sand-ribbed surface treatment. Some compression tests for each mixture were performed at the same ages and temperatures as the experimental plan in pullout to determine the influence of high temperatures on concrete. The study completed with some complementary tests on the CFRP rods using optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM), from the evaluated pullout samples. The high temperature significantly affected the ribbed CFRP bars by diminishing their bond stress and did not affect the sanded CFRP bars. This uneven behaviour and the influence of high temperature on concrete resistance at the age of 180 d is justified.