In general the coefficients of thermal expansion for unfilled (lower modulus) and filled (higher modulus) products are ~40-100 and 20-40 10^-6 C^-1 respec- tively. This compares with ~10 x 10^-6 C’^-1 for typical substrate materials and can lead to the development of significant thermal stresses. Thus for high modulus systems which undergo little stress relaxation, temperature changes ~30ëC can lead to stresses which, over time, can lead to shear failure in a concrete surface, loss of adhesive bonding from a steel substrate or cracking of the resin.
Closer matching can be obtained by careful attention to filler type and loading, and obtaining the best balance between thermal expansion coefficient, modulus and stress relaxation.
The fire performance of these resin-based materials is inferior to steel or concrete and must be taken into account when considering potential applica- tions. Whilst this factor would preclude their use in a few situations, there are many where it is of little consequence.
