The development and the future of advanced polymer composites in the civil infrastructure

摘要

A polymer composite is a material consisting of fibres bound into a polymer matrix to maximise specific performance properties of the final product. A composite structural system is one in which two dissimilar materials are combined to form an efficient component such that, when under load, the two materials act to maximise specific performance properties. Both of these definitions relate to composite structural systems relevant to the civil infrastructure. Composites in structural/civil engineering are utilized in broadly three ways, these are: (a) as load bearing infill panels, (b) as all composite material structures, (c) as one of two or more materials which are combined to form a structural system and to act compositely under load The development of each of these systems will be discussed separately as observed from a UK perspective. Glass fibre/polymer composites (GFRP) were first introduced into the UK during the Second World War as materials suitable for housing radar and electronic equipment. GFRP composites are non-conductive, consequently, no distortion of radio waves occurs as they are transmitted through the material. Similar housings are currently used on the north east coast of England and generally consist of eight or more segments bolted to a steel base ring which is attached to concrete foundations and to a top cap moulding made in GFRP. Adjacent panels are connected by return of flanges which, when correctly sized, can form an integral frame within the radome. From the late forties to the late sixties the interest in and the use of polymer composites in the civil infrastructure was sporadic and any systems which were developed were expensive. In addition, because of the ease of manufacturing GFRP hand lay-up systems a number of unscrupulous small manufacturers produced cheap and inferior components which would generally have had no post-cure; these composites degraded very quickly and damaged the reputation of composites in the civil engineering industry.