Self-Healing Potential and Phase Evolution Characterization of Ternary Cement Blends

The autogenous self-healing of cementitious material micro-cracks might lead to the service-life extension of structures. However, most of its aspects are still unknown. This paper investigates the self-healing capacity of ternary cement blends including metakaolin (MK), ground granulated blast-furnace slag (BFS), limestone (LS), and siliceous filler (F). Morphology and healing precipitation patterns were studied through the optical microscopy of artificial micro-cracks, global healing product mass monitoring, and XRD and TGA used to identify and quantify mineral formation. The self-healing potential index is introduced based on the mass measurements. It was found that the formulation containing 10% MK presented the highest healing potential at an early age (<28 days), while the formulations containing 20% BFS with 10% LS/F showed a higher healing potential at an older age (cracked after 28 days of curing). Calcite, C-S-H, and portlandite were found to be the main healing products alongside specific formulation-dependent compounds, and it was observed that the calcite's relative quantity generally increased with time. Finally, the evolution of the self-healing product phases was accurately monitored through XRD and TGA measurements.