Fracture stability and micromechanics of Strain Hardening Cementitious Composites

Innovative cementitious composites endowed with strain hardening behavior, namely UHPFRC, have been successfully employed in several industrial applications, such as bridge engineering and nuclear waste container prototypes, where the crack impact on the durability is of main concern. However, the material ductility of such composites exhibits a complex dependence on the fiber distribution that has been an important issue in the design recommendations ( AFGC, 2002 ). In this paper, we develop an approximate energy-balance approach to link the overall damage to non-uniform fiber distribution. The thermodynamics principles and the micromechanics based secant stiffness formulation allowed us to derive the non linear constitutive stress-strain relationship of the material from the fiber distribution and properties of the composite phases. Finally, the model implication on the stability of the post-cracking behavior is discussed together with an example of industrial application for nuclear waste container.