Role of Crystalline Admixtures and Silica Fume on the Self-Healing Effectiveness of Lime-Based TRM Systems

This study investigates the self-healing effectiveness of TRM composites consisting of glass textiles embedded in lime-based mortars. Four mortar mix designs were examined, incorporating crystalline admixtures and/or silica fume. Capillary absorption and three-point bending tests, complemented by detailed microscopic analyses, were carried out to experimentally assess the self-healing ability after one month of healing, and compare it against the performance of a reference composite system (i.e. without any inclusions in the mortar). The results highlight the favourable action of silica fume in enhancing the self-healing performance of TRM composites on the basis suitably defined indices, i.e. sorptivity, crack closure and stiffness recovery. The pozzolanic reaction was evidenced to be the dominant healing mechanism, but can potentially limit the action of crystalline admixtures. The results pave the way towards the functionalisation of TRM systems, tailored to meet the specific performance criteria of heritage structures.