ABSTRACT
Introduction Composite materials, such as the glassfibre-reinforced materials glassfibre-reinforced polyester (GRP), glassfibre-reinforced concrete (GRC) and glassfibrereinforced gypsum (GRG), rely for their utility on the advantageous combination of the disparate physical properties associated with the individual component materials. This is possible when a strong bond between the glass fibres and the matrix material ensures that the two materials within the composite act in unison. Thus polyester, which alone has a very low modulus of elasticity, when reinforced with glass fibres produces a material which is rigid enough for use as a cladding material. Concrete, which alone would be brittle, when reinforced with glass fibres, may be manufactured into thin, impact-resistant sheets. Similarly, glassfibre reinforcement in gypsum considerably increases its
Glass fibres The glass fibres for GRP and GRG are manufactured from standard E-glass as shown in Figure 11.1. Molten glass runs from the furnace at 1200°C into a forehearth, and through a spinneret of fine holes from which it is drawn at high speed down to approximately 9 μm in thickness. The glass fibres are coated in size and bundled before winding up on a collet. Subsequently, the glassfibre ‘cake’ is either used as continuous rovings or cut to 20-50 mm loose chopped strand. Glassfibre rovings may be manufactured into woven mats; chopped strand mats are formed with organic binder.
