ABSTRACT
Fiber reinforced cement composites have made striking advances in recent years, due, on one hand, to several technological developments (involving the matrix, the fiber, the interface, and the composite production process) and, on the other hand, to a better understanding of the fundamental mechanisms controlling their particular behavior. The attribute "high performance" implies an optimized combination of properties such as quasi strain hardening behavior, multiple cracking, strength, toughness, energy absorption, stiffness, durability, and corrosion resistance. However, so far only the combination of strength and toughness have been of interest in most applications. A review of the conditions leading to quasi strain hardening and multiple cracking behavior and its modeling using either the mechanics of composite materials or fracture mechanics is provided in this Chapter. Three approaches are described. The solutions generally identify a number of controlling parameters such as the fiber reinforcing parameters and the bond at the fiber matrix interface. They also leads to defining a critical volume fraction of fibers above which quasi strain hardening and multiple cracking can be guaranteed. An analysis of the various solutions is undertaken and differences between them are pointed out. It is noted that, in spite of showing similar trends for some ranges of parameters, these solutions can lead to significantly different results, implying that fundamental differences exist in the underlying principles leading to their development. A discussion related to toughness indices and fracture energy is also included. It is observed that toughness indices also can be used to describe quasi strain hardening and multiple cracking, however, they cannot be used to rationally differentiate between two composites. The fracture energy of the composite in tension is also needed. Finally, some future research needs and needs for additional characterization of HPFRCC are pointed out.
