P B LOURENÇO1, J C ALMEIDA2, J A BARROS1
1 University of Minho, Department of Civil Engineering, P-4800-058 Guimaraes, Portugal
2 Instituto Piaget, ISEIT/VISEU, Estrada do Alto do Gaio, P-3510-651 Viseu, Portugal
Softening is a gradual decrease of mechanical resistance resulting from a continuous increase of deformation imposed on a material specimen or structure. It is a salient feature of quasi-brittle materials like clay brick, mortar, ceramics, stone or concrete which fail due to a process of progressive internal crack growth. Such mechanical behaviour is commonly attributed to the heterogeneity of the material, due to the presence of different phases and material defects, such as flaws and voids. For tensile failure this phenomenon has been well identified for concrete but very few results exists for clay brick. In the present paper, the results of an extensive set of tests carried out at University of Minho and including three different types of brick under uniaxial tension will be presented. Both tensile strength and fracture energy are quantified, with recommendations for the adoption of practical values.