Synergistic effects of different ageing environments and sustained flexural loading on the durability of pultruded GFRP profiles

This paper presents an experimental study about the synergistic effects between different exposure environments, likely to be found in civil engineering applications, and sustained flexural loading on the durability of pultruded glass fibre reinforced polymer (GFRP) profiles. Two off-theshelf GFRP profiles, comprising E-glass fibres and vinyl ester or unsaturated polyester resins, were subjected to sustained bending at service load levels corresponding to 10% and 20% of their flexural capacity; simultaneously, the profiles were exposed to the following three ageing environments, for periods of up to two years: (i) outdoor environmental exposure in a mild Mediterranean climate; (ii) hygrothermal exposure by continuous condensation at 20 ( +/- 2) C-degrees, and (iii) indoor controlled environment at 23 ( +/- 2) C-degrees and 50 ( +/- 10)% relative humidity. The environmental exposure caused reductions in the flexural strength of unloaded specimens of 4%-15%, which were higher in case of hygrothermal exposure. The sustained service loads acting synergistically with the different ageing environments caused negligible additional degradation of the flexural strength of both types of profiles. These results, together with the data available in the literature, indicate that for the service load levels found in civil engineering applications, durability studies can be carried out without considering the synergistic effects of sustained loading, significantly reducing their complexity.