This literature review has examined the use of FRP composite materials as a potential retrofitting technique for civil structures. Importantly, the various material properties, bond mechanisms, durability issues and fatigue resistance have been discussed. Studies exploring the performance of CFRP repaired steel have strongly indicated its potential as a rehabilitation material. These systems offer many improvements over the current bulky and less chemically resistant methods of bolting or welding steel plate patches. This review has established and highlighted the factors that affect CFRP/steel bond durability, namely surface preparation, curing, corrosion, fatigue loading, temperature and moisture ingress through studies that focus on their effect. These studies, however, often focus on a single influencing factor or design criteria. Only limited studies have investigated multiple parameters applied simultaneously, even though they commonly occur together in industrial practice. This review aimed to summarise the numerous influencing parameters to give a clearer understanding of the relevance of CFRP repaired steel structures.

This article presents an investigation on the durability of different glass-fibre-reinforced polymer composites when subjected to harsh outdoor conditions, including freeze/thaw cycles, ultraviolet radiation and moisture, as well as when used with seawater sea-sand concrete for construction applications. To achieve this, the effects of a number of parameters, including the environment of exposure, exposure time, profile cross-sectional configuration and orientation of fibres, on the mechanical properties of different glass-fibre-reinforced polymer composites were studied. To investigate the degradation of the mechanical properties, three-point bending, compression and tension tests were conducted on both reference and conditioned samples. Moreover, scanning electron microscopy analyses were performed to examine the contribution of microstructural deterioration to the damage mechanisms of the conditioned composites. Finally, the test results were used to develop empirical regression models to predict the level of retention of mechanical properties of different composites under different environmental conditions. The findings showed the maximum flexural, compressive and tensile strength reductions to be 35%, 48% and 37%, respectively, with regards to the pultruded profiles exposed for 3000 h to freeze/thaw cycles followed by 90 days of seawater sea-sand concrete immersion, while the flexural strength reductions recorded for the vacuum-infused samples subjected to 2000 h of freeze/thaw cycles followed by 90 days of seawater sea-sand concrete immersion were 28%, 72% and 56% for the unidirectional, woven and chopped strand mat laminates, respectively.