Self-healing assessment of fibre reinforced cementitious mortars developed for 3D concrete printing: recovery of mechanical performance and self-sealing capability

This study investigated the self-healing capability of two fibre reinforced cementitious mortars, with and without crystalline admixture, which were specifically developed for 3D concrete printing. Four-point bending tests were carried out to assess the recovery of mechanical properties, focusing on resistance and stiffness recovery indexes. Two residual crack opening displacements of 50 μm and 500 μm were imposed on the different series of the specimens to compare their influence on the self-healing capability. Crack self-sealing efficiency was investigated by capturing crack images using a digital microscope. In addition to the assessment of the self-healing efficiency over time, the relationship between mechanical recovery indexes and average crack widths, as well as the relationship between different recovery indexes were also studied. The results showed a higher recovery performance for mixtures with crystalline admixture in the case of stiffness recovery and self-sealing capabilities. Moreover, the results showed a decreased on the healing efficiency with the increase of the crack widths.