Effects of loading rate on the fracture of cementitious materials

Cement paste, mortar, and concrete were studied to examine the influence of loading rate on operative toughening mechanisms. The fracture toughness of cement paste was found to be independent of crack length, while mortar and concrete exhibited strongly rising resistance curves. In the case of cemen t paste and mortar, the peak fracture toughness was found to be independent of the loading rate. Ln concrete, the peak toughness was found to decrease with increasing loading rate. Surface roughness measurements were performe d to understand the effect of loading rate on the fracture mechanisms. The roughness analysis coupled with fractography were found to correlate with t he toughness measurements. (C) 1999 Elsevier Science Ltd. All rights reserv ed.