A numerical model for the self-healing capacity of cementitious Composites

The self-healing capacity of cementitious composites, i.e. their capacity to completely or partially re-seal cracks, is studied in this paper. This phenomenon is investigated with reference to a previous experimental campaign dealing with a normal strength concrete which is kept in water after cracking (Ferrara and Krelani 2013, Ferrara et al. 2013). With reference to 3-point bending tests performed up to controlled crack opening and up to failure, respectively before and after exposure/conditioning, the recovery of stiffness and stress bearing capacity has been evaluated to assess the self-healing capacity. The SMM model (Di Luzio and Cusatis 2013) for concrete, which makes use of a modified microplane model M4 and the solidification-microprestress theory, is able to reproduce, as demonstrated, all the major effects of concrete behavior, such as creep, shrinkage, thermal deformation, aging, and cracking starting from the initial stages of its maturing up to the age of several years. The moisture and heat fields, as well as, the hydration degree are obtained from the solution of the hygro-thermal-chemical problem (Di Luzio and Cusatis 2009a, Di Luzio and Cusatis 2009b). This model is extended to incorporate the self-healing effects, in particular, the delayed cement hydration, which is the main cause of the self-healing for young concrete, as well as the effects of cracking on the diffusivity and the opposite repairing effect of the self-healing on the microplane model constitutive laws. A numerical example is presented to validate the computational model developed and to show its robustness.