Toughening in cement based composites .1. Cement, mortar, and concrete

This paper reviews the mechanisms of toughening in unreinforced cementitious materials, including cement paste, mortal; and concrete. The paper emphasizes the microstructural aspects of the different fracture processes that can potentially take place in these materials, and point out any possible interactions between these processes. Reference is made to three types of fracture process - frontal, crack tip and wake processes, and estimates of contributions to composite toughness of the individual mechanisms are included. It is shown that the fracture mode of a cementitious material closely relates to the types of fracture process that occur in that material. Based on the understanding of the conditions under which certain toughening mechanisms can take place in a given material, it may be possible to control the material fracture mode by tailoring the material microstructure. (C) 1996 Elsevier Science Limited.