A preliminary study on an effective and simplistic self-healing concept for cement using coarse clinker particles as the healing agent

Effective, low-cost and simplistic self-healing strategies for cement-based systems are attractive. This work proposed a concept where coarse clinker particles were used to replace cement and acted as the healing agent, and the effectiveness was validated by comprehensive studies. The results showed the high potential of the clinker sizes (40–60 μm, 60–90 μm, 0.5–1 mm) and replacement ratios (20–40%) under the studied conditions. For the clinker sized 40–60 μm, the 28d tensile and compressive strength recovery rates achieved 1.12 and 0.91, and the 56d crack sealing width and area reached 300–400 μm and 83.4%–94.4%, which even exceeds conventional autonomous self-healing strategies. The microscopic analyses indicated that larger clinker particles affected reaction kinetics of hydrating particles and improved spatial distribution of the hydration products. By retaining abundant unhdyrated parts and leading to more uniform distribution of the hydration products, the coarse clinker particles significantly improved self-healing properties of the cement mixes.