Influence of fiber dispersion on the performance of microfiber reinforced cement composites

High performance fiber reinforced composites are identified by their enhanced elastic behavior, pseudo-strain hardening response and toughened post-peak response. If the composite is adequately reinforced by fibers, the bridging action will transfer the load and multiple cracking will occur. This study investigates the effect of dispersion of fibers on the multiple cracking behavior of fiber reinforced composites. Electronic Speckle Pattern Interferometry technique is used to record the location of crack initiation, sequence of the multiple cracking and corresponding cracking stresses. Microstructural parameters at each crack location are statistically quantified by the theory of point processes. The size of the fiber free areas and fiber clumping are calculated at the crack cross-sections. By using Linear Elastic Fracture Mechanics, fracture toughness of the matrix is calculated. A strong relation between the cracking stress and the fiber free areas in the composite is observed. It is shown that the toughness of the composite depends on the fiber clumping at the first crack cross-section.