A study on polymer composite strengthening systems for concrete columns

An experimental study was conducted to investigate the effects of various composite wrapping systems with different fibres (E-glass and carbon), resins (vinyl-ester and epoxy) and architectures on the strengthening efficiency for wrapped concrete columns. Raw material costs were evaluated to identify the cost-efficiency of each individual system. The results indicated that the use of E-glass fibres with vinyl-ester resin to reinforce concrete columns externally is effective with a low cost of raw materials. The epoxy resin-based system does not show much improvement in the load carrying capacity. The small R/T ratio (thickness of wrap/radius of concrete column) may cause a low strengthening efficiency. Glass fibre mats were hybridised with carbon fibre layers to obtain better mechanical properties and an increased thickness of the composite wraps. Reinforcing efficiency is also highly dependent on the composite architecture. The fibre reinforcement in the hoop direction gives a high confining efficiency to the concrete columns. However, a certain amount of fibres in the axial direction are still needed in designing composite wraps, especially for long, slender columns.