Under injection pressure, these materials can rise and cause a leak. If a coating, sealant or paint has been applied to concrete, it must be removed before laying the paste epoxy (epoxy mortar). If the surface coating covers the crack, it may be necessary to route the opening of the V-shaped crack using a grinder to overcome surface contamination. Cracks in poured foundations can be repaired by low-pressure injection of an epoxy or polyurethane foam material. For the repair of cracks in concrete floors, there are certain epoxy and polyurea materials, suitable for such tile repairs.
Resin injection is based on repairing cracked or delaminated concrete and to seal cracks in concrete to prevent water leakage. Two basic types of resins and injection techniques are used to repair concrete; epoxy resins and polyurethane resins. Epoxy resins cure to form solids with a high strength and a relatively high modulus of elasticity. Microfine cement suspensions are not flexible and are therefore rigid, polymer-modified injection materials that do not adapt to movement. If these materials are used to bounce cracked concrete that is subsequently exposed to loads exceeding the tensile or shear strength of concrete, it should be excepted that cracks will.
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. If you use a fast-curing bonding material, clean the dripping epoxy with a cotton cloth and reapply the paste to the material. Typically, an epoxy resin for injection is a low viscosity, moisture tolerant material that sets slowly and has a high modulus. The viscosity, flexibility and behaviour of the material in contact with water are especially important, which can significantly influence the effectiveness of the injection. This specification sets standards for materials and equipment, work execution, quality control in the field, applicator and worker qualifications and provides information for measurement and payment. Injection is a procedure of pumping cement, polyurethane, epoxy or acrylate-based material into damaged or cracked structures to safely seal leaks, repair compromised structures and make them airtight again in the long term.
Acrylate resin based materials seal and waterproof leaks through their hydrophilic swelling behavior on contact. For example, the injection of curtain with PU gel into the space between the structure and the floor requires lower injection pressures but higher rates of material flow. Once the capping paste is used, the ports are drilled or installed, and any loose materials and dust are removed from the cracks, epoxy injection can begin. Epoxy and other resins lose strength when exposed to fire or sustained elevated temperatures and flame retardant protection is required for such structural repairs. Epoxy resins that are labeled as water insensitive during curing can develop milky white bond lines if injected into wet or damp cracks.
