On estimates of durability of FRP based on accelerated tests

Structures externally rehabilitated with fiber reinforced plastics (FRP) are often exposed to aggressive environmental conditions that dictate deterioration mechanisms and shorten their structural life-cycle. That degradation and ensuing failure may be due to a combination of factors and the environmental conditions leading to such failures include cyclic temperature variation, sorption of saline moisture due to salt fogging or dry-wet cycles and immersion in water. This study seeks to contribute to better knowledge of the phenomena involved, by studying degradation of GFRP laminates through tests of mechanical strength after accelerated aging designed to estimate long term natural degradation. The measured degradation is extrapolated to other environmental situations likely to occur for longer periods using Arrhenius type of analysis. The validity of the generalizations based on parameters derived from diffusion studies or from the tensile strength tests is examined. It is preliminarily concluded that Arrhenius equations based on experiments made after salt fogging at 30. °C, 45. °C and 55. °C are not applicable. The extrapolations based on diffusion laws were found unsuccessful. However it was possible to extend the results after accelerated aging to prototype conditions in the case of immersion in salt water by application of Arrhenius methods.