Bond performance between FRP tubes and seawater sea sand concrete after exposure to seawater condition

Abstract

In this study the durability of the bond between different fibre reinforced polymer (FRP) tubes and seawater sea sand concrete (SWSSC) under seawater condition is investigated. Concrete filled pultruded glass fibre reinforced polymer (GFRP) tubes and filament winding GFRP, carbon fibre reinforced polymer (CFRP) and basalt fibre reinforced polymer (BFRP) tubes were exposed to seawater at 25 °C and 40 °C for 1, 3 and 6 months. Push-out tests were carried out to study the bond performance of concrete filled FRP tubes (CFFT). The bond strength changes compared to the reference samples, in terms of the mechanical and chemical bonds, were calculated. The results showed that for all cases except one condition that had the same value as the reference, the maximum bond strength of the tubes increased due to the conditioning, however, the bond strength at the chemical adhesion breaking moment decreased by the conditioning. In other words, the friction coefficients of the samples increased due to conditioning, while the chemical adhesion decreased. Equations are proposed to predict the bond strength corresponding to slip initiations.