Co-authors​ :

 José SENA-CRUZ (PORTUGAL), Claudio LEITE , Marco JORGE , Luís CORREIA , Tarikul HASAN (PORTUGAL), João R. CORREIA (PORTUGAL), Mário GARRIDO , Susana CABRAL-FONSECA (PORTUGAL) 

In 2022, the European Committee for Standardization (CEN) published the Technical Specification CEN/TS 19101: 2022 - Design of fibre-polymer composite structures (herein referred to as TS). The TS constitutes a landmark towards the widespread application of composite materials in the construction sector, and applies to buildings, bridges and other civil engineering structures, providing a general basis for the design of all-composite structures or hybrid structures, combining composite members with members made of other materials. The TS covers three main types of composite components and members, namely, (i) laminates, (ii) profiles, and (iii) sandwich panels. During the development of the TS, the Project Team identified, among other aspects, relevant knowledge limitations concerning the durability of composites, namely: (i) the general lack of data about the durability performance of composites under different environmental degradation factors, (ii) the lack of long-term results, and (iii) the lack of data for relatively thick composites, typically used in the construction sector.

To tackle these issues, a comprehensive experimental program is being carried out to investigate the durability of relatively thick glass fibre reinforced polymer (GFRP) laminates. Composites produced by two typical manufacturing processes (pultrusion and vacuum infusion) and using two of the most commonly adopted resin types (unsaturated polyester and vinyl ester) are being studied under accelerated laboratory ageing and natural (in-situ) weathering.

This work provides preliminary results regarding pultruded GFRP plates with 8 mm of thickness, exposed to (i) accelerated thermal ageing at different temperatures, namely 15 °C, 20 °C, 40 °C and 60 °C for 12 months, immersed in water at 20 °C for 12 months, and thermal cycling between 15 °C and 60 °C for 100 cycles; and (ii) natural ageing for 12 months in four different places over Portugal, mainly involving exposure to moisture, thermal and freeze-thaw cycles, and UV radiation. After exposure, the degradation in terms of the thermomechanical and mechanical properties of the aged GFRP plates was evaluated through different types of tests, namely: (i) dynamic mechanical analysis – DMA (ASTM D7028), (ii, iii) tension at 0 and 90 (EN ISO 527-4), (iv) compression (EN ISO 14126), (v) flexure (EN ISO 14125), (vi) in-plane shear (ASTM D5379), and (vii) interlaminar shear (EN ISO 14130). Furthermore, the effects of the type of ageing (natural and accelerated ageing) and resin (unsaturated polyester and vinyl ester) on the overall durability are also provided, as well as comparisons between the obtained results and the durability design provisions given in CEN/TS 19101: 2022.