RELATIONSHIP BETWEEN FRACTURE SURFACE-ROUGHNESS AND FRACTURE-BEHAVIOR OF CEMENT PASTE AND MORTAR

Fracture surfaces of cement and mortar specimens were characterized using a confocal microscope to create three-dimensional computer-based topographic maps. The texture of the fracture surfaces was quantified using image analysis techniques to compute a roughness parameter and fractal dimension. Total porosity, pore-size distribution, compressive strength, and fracture properties of the specimens were determined and compared with the roughness parameter. Fracture properties were determined by notched-beam tests and the results were analyzed both by using conventional linear elastic fracture mechanics as well as a compliance-based approach that incorporated R-curve type of behavior. A positive correlation between fracture surface roughness and fracture toughness was demonstrated.