Epoxy injection is an economical method of repairing non-moving cracks in concrete walls, slabs, columns and piers and is capable of restoring the concrete to its pre-cracked strength. Prior to doing any injection it is necessary to determine the cause of the crack. If the source of cracking has not been determined and remedied, the concrete may crack again.

Injection of epoxies under pressure may be used to bond the cracks having greater than or equal to 0.05mm opening. This method is not applicable if the crack is active, the cracks are large in number, or when the water leakage can not be controlled. If the cause of the cracking has not been corrected, it will reoccur near the original crack. Extreme caution must be exercised when injecting cracks that are not visible on all surfaces.

Epoxy injection is commonly used to restore the pre-cracking condition of the member without increasing its strength. The epoxy tensile bond to the concrete substrate is stronger than the concrete’s tensile strength. Future cracking may occur at the same load as that of the original uncracked member but at different locations. Strengthening is provided by installing additional reinforcement across the failure plane in combination with the resin injection. Frequently, internal or external reinforcement is installed in combination with the epoxy injection for strengthening and restoration. Crack injection can be successfully performed on cracks as narrow as 0.013 mm in width with general epoxy injection resins. Cracks with less width can be injected with epoxy or other polymer systems having a low viscosity of 200 cps.

Poured foundation cracks may be repaired by using low-pressure injection of an epoxy or polyurethane foam material. For the repair of concrete floor cracks, certain epoxies and polyurea materials exists, suitable for such slab repairs.

One of the most versatile, problem solving products available in epoxy systems today is Epoxy Injection Resin. Structural restoration of concrete by epoxy injection is very often the only alternative to complete replacement. It therefore results in large cost savings. Injection protects the rebar and stops water leakage.

Epoxy injection of concrete cracks has been used for decades. When properly installed it is still working as well as it did right after it was installed.

Epoxy Injection Resin is a system for welding cracks back together. This welding restores the original strength and loading originally designed into the concrete. Epoxy injection restores the structural qualities the concrete design intended. In other words under most conditions it makes the concrete as good as new. It creates an impervious seal to air, water, chemicals, debris, and other contamination.

Other waterproofing injection systems like urethane resin will seal the crack from water but will not repair the the member structurally.  Not repairing a member structurally makes the member vulnerable to additional structural decay. This structural advantage that an epoxy injection repair gives, makes it the best choice for most situations.

A crack, obviously, is a sign of failure caused by stresses, inadequate design, improper curing, etc. One of the dangers of a structural crack is the effect that it has on the reinforcing bar. The reinforcing represents one of the main structural values of the concrete.

Cracks left unprepared allow moisture, road salts and other contaminants to penetrate and attack the rebar. The rebar deteriorates, losing the structural value. Loosing the entire structure is often the result. You can see this demonstrated in hundreds of neglected bridges across the U.S.

Epoxy injection resin has two purposes. First, it effectively seals the crack to prevent the damaging moisture entry. Secondly, it monolithically welds the structure together. Most people assume that this welding of the structure is the most important result of the repair. Actually what is most important is the sealing the rebar and preventing it from deteriorating.

The sealing properties of the injection prevents premature deterioration of the reinforcing. This can be of equal, or in some cases greater importance than the structural welding. It would theoretically always be desirable to get this welding effect.

Because the bond strength of epoxy to concrete is greater than the tensile strength of concrete, epoxy injection can restore the structural integrity of the concrete when applied to cracks 0.002 in. (0.05 mm) in width or greater. It is important to note that if the cause of cracking is corrosion of the reinforcing steel or if movement of the concrete is anticipated after repairs, epoxy injection may not be the best solution to the problem (3).

Shallow concrete cracks on horizontal surfaces such as bridge decks or the tops of pier caps can be repaired by gravity feed using epoxies or high-molecular weight methacrylate (HMWM). Both materials have very low viscosities (less than 100 cps) and low surface tensions; therefore, they can penetrate cracks with widths as narrow as 0.002 in. (0.05 mm) without the resin being pressurized (4).

Epoxy crack injection resins that are used for structural crack repairs conform to the requirements of ASTM C881,5 Type IV, and have appropriate viscosities for the crack widths and degree of confinement of the resin.6 Wider cracks that cannot be sealed on all sides require a higher viscosity (paste) injection material, whereas most cracks that can be sufficiently sealed are injected with epoxies at viscosities of 300 to 600 cps at room temperature. For applications at temperatures less than 60°F (15°C) and for fine cracks less than 0.01 in. (0.25 mm) in width, the viscosity of the epoxy needs to be lower, in the 150 to 225 cps range.

Crack injection concrete repair can be completed using air guns, hand-actuated delivery systems, spring- or balloon-actuated capsules, or single- or dual-component injection electric or air-driven pumps.

For consistent performance on large or critical projects, use of a dual-component pump with positive displacement and metering capabilities is recommended. After calibration, the epoxy materials are metered by the pump and mixed to the proper ratio in a static mixer just before entering the crack.

Epoxy grout is made from epoxy resins and an aggregate. This mixture gives the substance its excellent durability, hardness, and water-resistant properties. The rapid strength development, bond strength and chemical resistance supplied by epoxy resin and filler material makes it ideal for situations where vibrations, water, chemicals, and heat are regularly present. ANSI (ANSI A118.3) qualification is an important hallmark of great quality to look out for when evaluating epoxy grout options.

Epoxy grout is renowned for high strength and chemical resistance, making it a versatile solution for a wide range of specialist applications. Unlike other grouts where regular cleaning is necessary, the non-porous nature of epoxy resin does not allow dirt, grime or moisture to penetrate grout joints. 

Grouting materials are selected based on the type of load they will support. Dynamic loads are associated with reciprocating equipment, motors, generators, turbines etc. Static loads are associated with columns or non-moving equipment. Epoxy grouts offer unique performance advantages in many applications. They achieve strength quickly, allowing fast return to service or commissioning of equipment. Greater bond to the underside of a prepped baseplate, density and lower modulus of elasticity help to absorb impact and vibration. Low shrinkage and high tensile and flexural strengths optimize load transfer ensuring stable, secure alignment and protecting equipment from unnecessary wear and tear. Chemical resistance properties ensure they are durable even in harsh industrial environments. With more than 100 years of experience in precision equipment grouting, BASF Master Builders Solutions is an early developer and pioneer in both cementitious and epoxy grouts. We understand not only the in-service performance demands that our grouts must meet, but also the inter-relationship between various physical properties and application criteria that must be carefully considered. BASF has applied advanced chemistry to balance the physical properties of compressive strength, bearing area, chemical and high temperature resistance, shrinkage and creep with the sometimes difficult yet also very important application enablers of flow and working time, to provide uncompromised and durable support, protecting the equipment investment by improving reliability, operating efficiency and life cycle of machinery.

RECOMMENDED USES
•    Suitable for use on damp substrates
•    Grouting heavy duty supports beneath crane and transporter rails
•    Anchoring bolts, bars and fixings
•    Bonding new to old concrete
•    Adhesive promoter
•    Filling in holes, cavities
•    Repairing cracks in horizontal surfaces
•    Grouting off column bases
•    As a high strength repair mortar when mixed with Patchfix Filler
•    As a protective coating for concrete and steel structures
•    Reinforcement bar primer
•    Corrosion protection on steel reinforcement prior to application of concrete repair mortar
•    Grouting from 5mm to 120mm in a single application

FEATURES AND BENEFITS 
•    High flow properties
•    Bonds to damp substrates
•    Rapid hardening and strength gain
•    High chemical resistance
•    Pre-measured kits make for ease of use
•    High tensile and compressive strength
•    100% solid epoxy
•    Excellent adhesion to most substrates
•    Cures at temperatures down to 5oC
•    Negligible shrinkage
•    High mechanical strength
•    Solvent free
•    High early strength

Chemical anchoring is a technique for fastening to concrete and similar substrates that provides more flexibility than mechanical anchoring.

A mechanical anchor, such as a sleeve anchor, Dynabolt®, wedge anchor or drop-in anchor, is inserted in the concrete and expands upon tightening. This expansion causes the anchor to grip the wall of the hole and provide an extremely strong hold. Whilst being a very popular and economical option, there are, however, some limitations.

So, what is a chemical anchor’s advantage? With chemical anchoring, a resin is injected into the hole prior to insertion of the stud. With this, the chemical naturally fills in all irregularities and therefore makes the hole airtight and water proof, with 100% adhesion.
And with mechanical anchors, each predetermined size—length (embedment) and diameter—has its own load capacity limits. Chemical anchors have virtually unlimited embedment depth, so you can embed any length of rod into the hole to increase the load capacity. And if you choose to use a larger-diameter hole with a thicker rod, you increase load capacity again.

Chemical anchoring (or commonly called "chemical anchor") is based on the idea of ​​fixing a threaded rod or metal rebar to cracked or uncracked concrete (concrete older than 30 days) or to rocks. Furthermore, it is possible to apply to brick walls (wall) instead of mechanically by friction or by interlocking, using a rigid resin (glue).

This material is injected into the perforation that is previously cleaned with electric or manual blowers for a better adherence to the roughness of the perforation, ideally, in addition to the blower, use metal brushes to clean the remains of the perforation in the best possible way. In concrete and walls, it is carried out with drill bits for concrete. In rocks, diamond holes are drilled, not bits, and special chemical anchors are used capable of achieving adhesion in the smooth drilling and perfect diamond drilling results. Pure Epoxy in most cases.

The benefits of this material are the mechanical resistance and the hardening speed, which in many cases is 45 minutes. For this purpose, it is necessary to use two-component resins, a resin plus the catalyst or hardener, which are characterized by a chemical reaction that cures or dries after minutes.