RESULTS AND DISCUSSION
A typical set of results is presented in Table 2. Three Grades of normal density concrete, a lightweight aggregate (Lytag) concrete and a polymer concrete have been studied. The three normal density concretes represent typical low, medium and high strength concretes. The lightweight aggregate concrete was designed to have the same strength as the low strength concrete and was studied, in particular, in terms of the fracture planes developed. The polymer concrete mix is typical of that which has been studied extensively in the same laboratory in terms of its mechanical and physical properties.