RELATIONSHIP BETWEEN FRACTURE SURFACE-ROUGHNESS AND FRACTURE-BEHAVIOROF CEMENT PASTE AND MORTAR

Fracture surfaces of cement and mortar specimens were characterized us ing a confocal microscope to create three-dimensional computer-based t opographic maps. The texture of the fracture surfaces was quantified u sing image analysis techniques to compute a roughness parameter and fr actal dimension. Total porosity, pore-size distribution, compressive s trength, and fracture properties of the specimens were determined and compared with the roughness parameter. Fracture properties were determ ined by notched-beam tests and the results were analyzed both by using conventional linear elastic fracture mechanics as well as a complianc e-based approach that incorporated R-curve type of behavior. A positiv e correlation between fracture surface roughness and fracture toughnes s was demonstrated.