Durability of fiber reinforced polymer composites under tropical climate

Abstract

A lack of in-depth knowledge of the long-term durability of fiber reinforced polymer (FRP) composite in real service condition restricts its extensive use in structural rehabilitation works. The organic nature of the matrix of the FRP composites, and the reinforcing fibers, make them susceptible to attacks of various tropical weathering factors, namely, ultraviolet (UV) ray from sunlight, moisture and heat, when used externally. Therefore, in the first part of this study, the tropical climate was characterized and reproduced in an in-house designed weathering chamber to induce accelerated weathering effects on FRP composites and FRP-strengthened structural elements. In the second part, the observed glass fibers reinforced polymer (GFRP) mechanical properties variations in the accelerated weathering tests were incorporated in a proposed analytical model to predict the time-dependent behavior of FRP-strengthened beams under the weathering effects of tropical climate.Comparison with weathering test results showed that the effects of tropical climate weather were reproduced well in the proposed accelerated weathering test scheme. The tensile strength of the GFRP dropped over time when subjected to outdoor tropical climate, and the reduction of tensile strength of GFRP laminates is matrix dependent.In addition to the tensile coupons, 48 beam specimens were fabricated, exposed to 3 exposure conditions and tested to validate the applicability of the proposed model. The failure modes and ultimate loads of small-scale GFRP-strengthened beams changed with weathering time, and can be well predicted using the proposed model incorporating the material properties after weathering.