Epoxy injection is a reliable and effective method for repairing cracked or delaminated concrete. This technique is used to seal cracks in concrete to prevent water leakage and can be used in both vertical and horizontal applications. Epoxy resins are formulated with specific fillers to allow the penetration of small cracks and a low exotherm for larger cracks. This method is not applicable if the crack is active, cracks are large in number or when water leakage cannot be controlled.
Epoxy injection is an easy way to repair cracks in a structure and works great for horizontal, vertical and overhead applications. This method can be used when special sealing devices are available that cover the unsealed part of the crack and allow the injection of the adhesive directly into the crack without leakage. In vertical applications, start injection at the lowest port and advance upwards. In a horizontal application, start at one end of the crack and work your way to the other end.
Inject epoxy into the first port until it no longer flows into the crack. The method involves drilling a hole in the crack, approximately 20 mm in diameter and 13 to 25 mm below the apex of the V-groove section, where a fitting such as a pipe nipple or a tire valve stem is normally bonded with an epoxy adhesive. If the cause of the cracking has not been corrected, it will reoccur near the original crack. Great care must be taken when injecting cracks that are not visible on all surfaces. Epoxy and other resins lose strength when exposed to fire or sustained elevated temperatures and flame retardant protection is required for such structural repairs.
There are some methods that inspectors can use to verify that the epoxy injection process has been effective and is sufficient to repair structural damage. For the repair of cracks in concrete floors, there are certain epoxy and polyurea materials, suitable for such tile repairs. Epoxy resins that are labeled as water insensitive during curing can develop milky white bond lines if injected into wet or damp cracks. It is difficult or impossible to inject resin into cracks less than 0.005 inches wide, while it is very difficult to retain injected epoxy resin in cracks larger than 0.25 inches wide, although high viscosity epoxies have been used with some success. Epoxy injection offers many benefits for concrete repair, including its ability to seal out water, its low exotherm for larger cracks, its ability to penetrate small cracks, its flame retardant protection, and its ability to be used in both vertical and horizontal applications.