Crack injection is a method used to repair cracks in concrete structures, such as walls and foundations. This process involves injecting a specialized material, often a polyurethane or epoxy resin, into the crack. The injected material expands and fills the void, effectively sealing the crack and preventing water infiltration. This technique is commonly employed in construction and civil engineering to enhance the durability and longevity of structures. It is particularly useful for addressing issues caused by water damage or settlement, ensuring that the integrity of the concrete is maintained and reducing the risk of further damage.