The Material Of Construction : Fiberglass & Resin

GRP is a composite material wherein the glass fibers with their high mechanical strength form the structural part, whereas the resin is the chemically resistant matrix which renders the product impermeable and bonds together the various fibers, thus enabling the stresses to be distributed.The nature of the material, glass fibers and resin which is employed ever more widely for constructional purposes, is very different from that of traditional materials.

In designing structures it must be borne in mind that reinforced plastics are an anistropic material in which the reinforcement can be oriented os as to obtain maximum mechanical strength in the direction of the stress.

The nature, quantity and disposition of the reinforcement are established on the basis of all the stresses present in the design.

Thus the laminate, or lay-up, is made, without being conditioned by thicknesses, at the same time as the product itself to be constructed on the basis of all the nominal and actual working conditions required.

We must also remember that in a product made of glass fibers and resin :

	The tensile strength only falls by 30-35% after a working lif of the order of 100 years as compared to the short-term strength, and that the structures are designed with a safety factor not lower than 7.5.
	The Young's modulus tends to increase with ageing
	Failure occurs not by a violent breakdown but through gradual weakening, which is usually to be found at the limit of elasticity of the fiberglass/ polyester - matrix bond.
	Residual Stains are always negligible