The post-fracture tensile (PFT) technique is well established in the studies of wake toughened ceramic systems. Through this experimental procedure, regions responsible for crack closure stresses are isolated and characterized, providing the constitutive stress-displacement relationship unique to the microstructure. This…
The post-fracture tensile (PFT) technique is well established in the studies of wake toughened ceramic systems. Through this experimental procedure, regions responsible for crack closure stresses are isolated and characterized, providing the constitutive stress-displacement relationship unique to the microstructure. This technique when applied to cementitious materials will offer a unique perspective to assess the effectiveness of sand grain morphology and size distribution. A mortar consisting of rounded sand grains ranging from 0.1 to 1.4 mm in diameter and cement provides baseline data for wake toughening properties in a cementitious material study. Using grain-size distribution and experimental stress-displacement results, we estimate that this rounded sand morphology effectively supports loads over a crack opening displacement (COD) of 1/15th the grain size. 1853 Recent attention in fracture mechanics of cementitious and ceramic materials addresses the wake process zone responsible for the toughening characteristics evidenced by a rising R-curve behavior. New design philosophies incorporating principles of flaw tolerance require not only the quantitative evaluation of this process zone but an understanding of the mechanisms affecting the distribution and magnitude of cohesive stresses transferred, as well. Several indirect methods have been advanced based on theoretical modelling studies to characterize the relationship between the bridging stresses and the crack opening displacement (COD) in the fracture process zone. Hillerborg et al. (1976), suggested a model for the analysis of initiation and propagation of cracks in concrete structures on similar lines of the Barenblatt (1962) and Dugdale (1960) model. In contrast to the single valued cohesive stress of a perfectly plastic metal, Hillerborg et al.