Influence of aggressive exposure conditions on the behaviour of adhesive bonded concrete–GFRP joints

• Published in: Construction & building materials 1998-12, Vol.12 (8), p.427-446
• Main Authors: Mukhopadhyaya, P, Swamy, R.N, Lynsdale, C.J
• Format: Article
• Language: English
• Subjects: Concrete–GFRP joints; Durability; Plate-bonding
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/S0950-0618(98)00030-0

This paper presents the interim results of an on-going study on the influence of aggressive exposure conditions on the behaviour of epoxy adhesive bonded concrete–glass fibre reinforced polymers (GFRP) joints. The type of specimen used in this study is a push-off double lap shear specimen. Twenty-four of these push-off specimens consisting of concrete prisms, 100×100×300-mm, bonded with 470-mm long, 90-mm wide, and 3.5-mm thick GFRP plates on two opposite faces were tested. The bond length of the plate over the concrete surface was 200 mm. Two different concrete strengths were used, and they were suitably air entrained. The specimens were subjected to three accelerated ageing regimes in the laboratory for approximately 9 months. The accelerated tests consisted of exposing the specimens to alternate wet–dry cycling in 5% sodium chloride solution, cyclic freeze–thaw in air with a temperature of 20°C and −17.8°C, and a combination of chloride immersion and freeze–thaw cycles. The specimens were comprehensively instrumented, and tested to failure after the exposure regime. The structural performance of the exposed specimens is then compared with that of similar control specimens kept in laboratory environment in terms of load carrying capacity, longitudinal force distribution, shear stress development in the plate, plate end slip, and differential movements between the plate and the concrete substrate. There was clear indication that all the exposure regimes increased the bond transfer length, the magnitude of the shear stress distribution and the plate slip. The combined chloride immersion/freeze–thaw cycles produced the largest differential movements between the plate and the concrete substrate. The duration of exposure, however, was not long enough to affect the strength of the joints. Overall, the results were very consistent, and showed that accelerated tests could inflict deterioration in the adhesive bonded concrete–GFRP joints.