Epoxy Injection protects rebar and stops water leakage.

Structural restoration of concrete by epoxy injection is very often the only alternative to complete replacement. It, therefore, results in large cost savings. One of the most versatile, problem-solving products available in epoxy systems today is Epoxy Injection Resin.
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 of 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 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. Losing 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 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 sealing the rebar and preventing it from deteriorating.
The sealing properties of the injection prevent premature deterioration of the reinforcing. This can be of equal, or in some cases, greater importance than structural welding. It would theoretically always be desirable to get this welding effect.

Jim Parker’s Epoxy Injection work at 9777 Wilshire Blvd, Beverly Hills, Ca. 90212

Imperial Bank epoxy injection

Epoxy Injection repair of Cracked Structural Concrete to repair the extensive  January 1994 earthquake damage. Our repair work restored the concrete shear walls to original strength stopping any shearing moments, sealing all cracks, protecting re-bar, waterproofing. It performs perfectly in 2021

Concrete Crack Analysis

As with all repairs and rehabilitation of concrete, the initial job analysis is the most important step. Epoxy Injection Resin will weld concrete cracks but, of course, will not repair the cause of the cracking. Analyze each potential injection application to determine the exact cause or causes of the cracking. Correcting the cracking problem can be fairly simple or may be difficult involving design changes.
Consult a structural engineer when design changes are necessary. Do this before starting the injection. Repairing cracks in building walls by Injection is effective after these design changes. Prevent future cracks by fixing the original cause of the cracking whenever possible.
Parking garages are an example of a cracking problem that requires a structural engineering analysis.
Often inadequate design for expansion/contraction is the cause for parking garage structural cracking. Avoid weld injecting a crack if there are not enough expansion joints. Sometimes flexible overlays can be used to overcome this defect. However, this does not encapsulate the rebar in a way that will totally stop the premature deterioration of the steel. Oftentimes additional joints are needed. Thus the analysis of cracking problems is critical.

Epoxy Injection that stands the test of time and climate

Injection Preparation

Proper job preparation is essential to ensure maximum results. Preparation before the injection is even more important. Once the resin is in the crack, there is no turning back. The two most effective systems for setting injection ports:
  • Surface Ports for General Purpose Use
  • Drilled for Special Uses Applications

Port Setting

It is imperative that if drilling uses the drill-type ports, it be done with vacuum attached swivel drill chuck and hollow drill bits. Concrete dust can be detrimental to the injection processes in several ways.
Any dust remaining in the drill hole near a crack can combine with the very low viscosity injection resin, forming a semi-paste. This paste can slow or even block the resin flow. Drilling a very tight crack with a solid drill forces dust into the crack. This seals the crack from resin flow. Do not allow shortcuts in the drilling procedures!  However, for most applications, the surface port is the easiest and most effective method.
Determining the spacing of ports is done by a highly experience applicator. This spacing is a factor in the tightness of the crack and the depth of the concrete substrate. Spacing is normally between four (4) and eight (8) inches.

Port Setting and Sealing

Align ports directly over cracks. That allows injection resin to flow into the crack—seal surface cracks. Sealing the exterior of cracks is done with Two-Part Epoxy Paste.

Testing The System

Test cracks that are ill-defined, or if dust or debris is in the crack. This testing may be done by injecting water into the crack area.
Water left in the cracks will not effect the injection process or the curing of the Epoxy.com Injection Resin. Heavier injection resin forces the water out the cracks. Water injection helps clean the cracked areas. More important is that it helps avoid the unexpected. This process of flushing the cracks is commonly skipped by more experience contractors, who can tell if there will be a resin flow by just looking at them. However, when in doubt, water testing is a must.
If the cracks contain algae, chlorinated water containing copper sulfate is injected. After pumping, this mixture is left overnight. The next morning the crack is flushed by pumping fresh water into it. This flushes it out before resin injection begins.
Efflorescence builds up on the bottom of a crack in a horizontal slab. Water in the crack extracting soluble calcium hydroxide is the cause. The water evaporates at the surface, leaving the lime, which later reacts with the carbon dioxide in the air to form limestone. The inside of the crack is frequently free of limestone and making it suitable for injection.

Resin Injection

Epoxy resin injection with any industry-standard 2:1 injection machine.  Injection resin is the only way of assuring quality installation. Single component caulking guns, pressure pots, or similar batching equipment are not suitable for injection.
Limit pressures to 40 p.s.I for most applications. Excessive pressures can create additional stress in the crack. It can also cause hydraulic lifting, rupturing of the cracked substrate, or further elongation of the crack. Low pressures allow gradual resin flow into the crack for deeper penetration. On vertical cracks, injection is started at the lowest point and continues upward on the crack area. While injecting the lowest port, the resin will flow to and out of the next higher port.
Starting at the LOWEST point, when the pure resin flows out the next port cap, the current injection port is capped, and then the injection is moved to the next port. Then injection continues in the port showing resin flow. This procedure continues until all ports are full.
Epoxy Injection Resin Systems should be of very low viscosity for most applications. That way, it will flow in the smallest hairline cracks.  See photos of core samples below. Resin can travel several feet from the point of injection. It may take some time before reaching the next port or penetrating through pinholes on the surface. Coring samples have shown that epoxy injection effectively fills cracks, including small voids and hairline cracks.

Concrete core samples

Note the epoxy resin has penetrated 100% of the cracks in this core sample showing proof of a high-quality epoxy injection job.

Injection During Extreme Weather

A cold substrate will cause an increase in the viscosity of the injection resin. This slows down the rate of injection—a hot substrate results in premature jelling of the resin with sequential loss of penetration. During extremely hot weather, an open bridge deck may exceed temperatures as high as 140 Degrees F. Special precautions are necessary before injection work can be done in such weather.
The precaution may be shading the bridge and water cooling. Always check substrate temperature. The injection machine and its hoses require isolation from extremes of temperature.
An epoxy injection that is undertaken during cold weather also requires special precautions.
When doing injection work in freezing conditions, determining if ice is present in the crack is critical. Determining if a crack’s inner surfaces are ice-coated is equally important. When injecting under these conditions, the resin will not bond to the substrate, and no structural rebonding will result. It is usually safer to preheat the portion of the structure you are injecting.
When heating a structure, do not overheat it. This closes the crack. When removing heat, the crack may rapidly open. This will rupture the resin before it has a chance to achieve the final cure. In most cases, indirect heating is much more desirable than direct heating. Maintain heat for several hours before and after the injection application.

Aesthetics

The color of the sealer material used in resin injection is concrete gray. They are difficult to remove. If aesthetics require complete cleaning, the sealing material can be removed by grinding. This is normally done at an additional charge to the OWNER.

Injection Against A Head of Water

Injection of Epoxy Injection Resin against a head of water requires a slightly different procedure than a normal injection. If water runs from a crack, applying a hydraulic cement (fast setting) seals the cracks and sets the ports. Epoxy pastes will not set up under this type of wet condition. The hydraulic cement seals the cracks and diverts all water flow through the injection ports.
Hydraulic cement is a fast setting, but it does not have the strength needed for an Injection Sealer. Epoxy Concrete Bonder can have the strength to prevent blowouts or leaks while injecting. After the hydraulic cement cures applying Epoxy Concrete Bonder. That solves this problem.
The injection process follows the procedures described before. The Injection resin forces the water out of the crack and through the adjacent ports. The resin has an amber color and does not look like water. Pure resin flows from the higher port before capping and moving on. The head of water will require increasing the injection pressure used.

INJECTING DELAMINATIONS & HOLLOW PLANES

Delamination of concrete structures is an area where injection can also offer selective repair. A prime example is bridge decks or other self-supporting structures. The most common delamination is the shearing of the concrete. This is commonly at the upper rebar mat.
Another common situation is the hollow plane that develops when concrete bridge piers are resurfaced. Old piers are encased in new concrete. Hollow planes in this type of application are common, especially against smooth sections of the old pier. Cracking then occurs on the surface perpendicular to the hollow plane.
This delaminated area is subject to chemical penetration from the surface and moisture, attacking the reinforcing bar. If the delamination is not repaired, traffic will cause the area to pop out by pounding on the delaminated upper concrete layer. Freeze-Thaw damage will also tear the concrete apart. The greater the number of freeze-thaws, the more water in the cracks during these free-thaws, the greater, and the quicker the damage to the concrete.
Map delaminations by drag chain, hammer, or sounding device. The damaged area requires no less than four (4) ports drilled for resin flow, depending on the size and shape of the delamination. This prevents the trapping of water that may be present.
The delamination is normally hollow planes that run along the reinforcing bar. When injecting the delamination, the resin will follow these hollow planed areas and travel several feet to fill the voids.

CONCLUSION

Epoxy Injection Systems effectively repair concrete cracks, delaminations, and hollow planes when used according to manufacturers’ recommendations. Job analysis and proper preparation are critical to ensure the maximum performance of the Epoxy Products or any other concrete repair products. The right equipment is critical. Proper setup continuous mixing epoxy injection machines must always be used with no exception. Injection staff and management must have the training and experience to do the work right the first time. The epoxy injection has to be done right the first time. There is no second chance. So your injection work must be done by well-trained and equipped, experienced personnel.