Autogenous Healing of High Performance Concrete Using Metakaolin

Concrete incorporates a natural self-healing capability that is primarily created by hydration and carbonation to repair small cracks. This ability is limited and is only activated when direct contact with water takes place. The study mainly dealt with crack repair and sustainability. For the repair of cracks, autogenous healing mechanism is adopted. Autogenous healing can be accelerated by the addition of mineral additives. The mineral additive used for autogenous healing is metakaolin. The use of metakaolin in high performance concrete can improve both the strength and durability properties of concrete. The ability of autogenous self-healing will increase with higher cement content. The experiment was conducted on high performance concrete of M70 grade. 10% replacement of cement with metakaolin is considered for the study. Specimens with addition of metakaolin and without metakaolin were subjected to 0 day, 3 days and 7 days curing. This study mainly focused on the strength retained, type of crack formed, propagation of cracks and amount of crack healed. The compressive strength and flexural strength at 7 day, 28 day and 180 days were carried out. Flexural strength test carried on beam specimens of size 700 × 150 × 150 mm was subjected to two-point loading. It has been observed that the specimens with metakaolin gives increased compressive and flexural strength than those specimens without adding metakaolin. The early age cracks in concrete structure will get reduced due to the addition of metakaolin. Also the addition of metakaolin promoted autogenous self-healing.