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Structural bonding is achieved by means of low viscosity and high viscosity epoxy injection resins. Thanks to its high adhesive tensile strength, epoxy resin provides permanent adhesion even to the smallest cracks and gaps in concrete and masonry. EP injection resins are compatible with masonry mortar, concrete, steel, foil and cable insulation. Epoxy injection resin is also very resistant to salts, alkaline solutions and acids that can damage the building structure.
Epoxy Injection Preparation
Structural analysis before injection Structural condition Hydrodynamic and hydrostatic conditions Voids Things to consider when repairing cracks;
General crack condition
Importance of cracks for the building structure Crack characteristics (crack type, crack propagation, crack width, crack width modification, etc.) provide us with information on these issues;
When using epoxy resin in masonry, all loose plaster/plaster layers at the injection level must first be removed and all porous joints and defective wall areas must be bonded with fast drying cement. Cracks to be filled must be free of dirt, oil, grease and other segregating agents. Crack edges should also be cleaned. When surface packers are used for epoxy injection, EP putty is used to repair cracks and install surface packers. The surfaces of the structural elements to be patched must be prepared to ensure adequate adhesion of the patch (>1.5 N/mm²).
Epoxy Injection Resin Application
The pressure during injection depends on the nature and condition of the building structure. Injection is started by first filling the lowest crack areas with epoxy resin. In horizontal cracks, the injection is applied from one direction to prevent air ingress. When injecting the last puck, the air vent (orifice) for the exiting resin is checked. A second injection should be done during the gelling phase of the material (approximately 30 minutes after the end of the curing time). Conditions to be considered when applying epoxy resins are the reaction rate, the temperature of the material and the structural element. High temperatures accelerate the reaction rate and low temperatures slow it down. Only pure epoxy injection resin, free from cleaning agents or other impurities, should be injected.
Application Stages with Injection Molding Machine
Transfer the mixed material into the hopper of the pump. It is mixed for a short time. Due to the natural heat of the injection pump, the service life of the material is reduced. As soon as the material in the pump chamber becomes hot, it must be used immediately or removed from the pump. After the epoxy resin has dried, the pacers are removed when the application is finished. Drill holes are sealed with suitable building materials and the surface is re-plastered. Epoxy is recommended for structural crack repairs;
Unlike polyurethane foams, epoxies will not expand. With epoxy, they turn into an incredibly hard solid that bonds solidly to concrete, making them ideal for structural repairs. Epoxy injection resins create a stronger structural bond than concrete.
Injection is typically used in horizontal, vertical and overhead cracks where traditional repair methods cannot penetrate or are too cost prohibitive. Before proceeding with a crack repair with epoxy injection, the cause of the crack and the need for a structural repair must be determined. If the crack does not compromise the structural integrity of the structure, injection with polyurethane grout or other non-structural materials may be a more viable option for filling the crack (e.g. leaking, stretching, etc.). When a structural repair is required, the conditions causing the crack must be corrected before proceeding with epoxy injection. If the structural crack is damp and cannot dry, a moisture resistant resin should be considered. Epoxies for crack injection are available in a range of viscosities from ultra-thin to paste-like to accommodate cracks of various widths. The main advantage of epoxies over other repair products is their high compressive strength. This makes epoxies ideal for cracks requiring structural repair.
