This study explores the role of subsequent hydration in healing cracks in cement-based materials, focusing on a water-cement ratio of 0.20 and aging up to 1260 days. A novel bond strength testing method and backscattered electron imaging (BSE) analyzed the relationship between bond strength and unhydrated cement. Techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) helped investigate crystal phase content and microstructural changes. Key findings reveal that subsequent hydration primarily produces calcium hydroxide (CH), calcium carbonate (CaCO3), and C–S–H gel. Bond strength notably increased to 36.08 % at 394 days, with a significant reduction in C3S and C2S phases and increases in CH and CaCO3. The calcium-silicon ratio varied across hydration products, with external products containing the highest ratio. The study demonstrates the transformation of C–S–H gel from low to high density and highlights the cohesive structure formation of CH and C–S–H gel, crucial for crack healing. Porosity showed an initial decrease followed by an increase, peaking at 54.14 % above the initial value. These findings underscore the importance of controlling unhydrated cement content for optimizing self-healing in cement-based materials.