Durability related design of GFRP bar reinforced concrete structures

Under harsh environmental conditions, a GFRP bar will undergo physical and chemical changes, which will lead to the degradation of the GFRP materials. The long-term properties of GFRP bars in concrete have been incorporated in the various international guidelines by adopting strength reductions or stress limiting factors assumed for GFRP reinforcement as a single environmental reduction factor. In this paper, the concrete pore structures (pore size, pore volume and pore connectivity), water content in concrete, the changing pH of concrete pore solution due to the carbonation and external environments were investigated. Based on the results of this research, new durability-related strength reductions factors, stress limiting factors for GFRP reinforcement under different exposure conditions, as well as concrete cover and water/cement ratio for different applications are proposed, which should lead to more accurate and cost-effective design of GFRP bar reinforced concrete structures.