Abstract

Carbon fibre reinforced polymers (CFRPs) are promising alternatives to steel reinforcement for marine and offshore structures. CFR Ps do not corrode but, in humid environments, it is important to ensure that the long-term durability of the CFRP is not adversely affected due to moisture absorption in the epoxy-matrix material. This research project focuses on two main issues: the long-term durability of the matrix dominated properties in CFRP reinforcement in isolation and the long-term bond performance between CFRP tendons and concrete in pretensioned structures. Exposure of CFRP tendons to moisture may be detrimental to matrix dominated properties such as bond strength, creep and dowel strength. The bond failure between concrete and internal CFRP reinforcement lies mainly in the resin layer of the CFRP . To take a conservative estimate of the matrix component degradation in CFRP tendons, samples were fully immersed in distilled water. Torsion tests were carried out over exposure time and the reduction in torsional shear stiffness (matrix dominated property) was recorded. Next, the long term performance of CFRP tendons was studied in a concrete environment by carrying out pull out tests in specimens immersed in water. The exposure in water seems not to decrease significantly the bond strength in sand coated CFRP tendons embedded in high performance concrete. The quality of the sand coating layer seems to dominate the bond behaviour between CFRP sand coated tendons and concrete. The need for better quality controls and standardisation in the manufacturing process is opportune and significant to ensure consistency between design guidelines and structural applications.