Preliminary investigations on the environmental effects on new heavyweight fabrics for use in civil engineering

As the use of advanced polymer composites (APC) in the civil engineering profession becomes more established, there is a need to identify potential problems associated with durability issues. The experimental durability study to be discussed in this paper, is part of a wider on going Brite-Euram Project to investigate the in-service characteristics of a hybrid Tee-beam constructed from concrete situated in the compressive part and, APC situated in the tensile part of the beam. The current investigation is concerned with the durability of the APC material when it is exposed to various environments. The APC part of the beam has been developed specifically for the construction industry and is manufactured from a composite of predominately unidirectional woven carbon fibre reinforced polymer (CFRP) and +/−45° stitched glass fibre reinforced polymer (GFRP) composite; the matrix material is a low temperature cure epoxy resin suitable for civil engineering construction. The coupon samples were exposed to environments of three different temperatures (viz. 22, 45 and 60 °C), water, saturated road salt solution and ultra-violet (UV) radiation after which they were loaded to failure under a tensile stress. Results have shown that a reduction in mechanical properties (longitudinal strength and stiffness) of the three composite systems is most evident at higher temperatures and after exposure to water.