Repair concrete cracks. Repairing concrete cracks doesn’t have to be a huge projection and you don’t have to always hire a concrete crack repair company. Most of the time, concrete crack repair companies use the same solutions you would if you did it on your own.
To sum it all up, there are two types of concrete wall cracks. Concrete wall cracks that are in need of structural repair and concrete wall cracks that aren’t. If you are trying to find out what caused your concrete wall crack, view our Basement Wall Cracks article.
Repairing Concrete Wall Cracks – Cause of Crack and Solutions
- If your concrete wall is in need of structural repair, and the crack is dry (not wet or leaking), you need an epoxy. Epoxy repair solutions offer a structural repair.
- If your concrete wall crack was caused by shrinkage, settling, or movement, you need a polyurethane crack repair solution. The polyurethane will create a permanent bond to the concrete but it is flexible. If the concrete wall shrinks, settles, or moves, the polyurethane will flex with the concrete – keeping the crack sealed. If you use an epoxy to repair these types of cracks, the crack will reform once the wall shrinks, settles, or moves.
- If you concrete wall crack is leaking or gushing, you need a polyurethane crack repair solution that is reactive with water. Epoxies can’t be used on wet cracks.
- If you have a hairline crack you want a high pressure polyurethane kit. Low pressure polyurethane kits with plastic ports are absolutely incapable of filling a crack completely. While low pressure injection kits claim to fill the crack, the simply offer a slightly deeper than surface seal. High pressure kits will inject the material into the crack and won’t stop until the back of the crack is reached and the entire crack is filled.
How To Repair Concrete Cracks Using a Polyurethane Resin
Repairing a crack sounds like it could be a lot of work – but it really isn’t. Repairing a concrete crack using the Foundation Armor concrete crack repair kit actually only takes about 10 minutes for every 10FT of crack. The best part about this crack repair solution is once you repair the crack – you never have to repair it again.
Definition of Terms
Refusal – when a crack or void area will accept no more grout under the prevailing pumping conditions (for reasons other than the pumpability of the grout).
Return time -the time taken for a grout, under certain application conditions to completely penetrate a crack, void, or network of cracks.
The most commonly used hydrophobic polyurethane resin (Foundation Armor Polyurethane Resin) which is accompanied by an accelerator (Foundation Armor 15x). The applicator/contractor is able to adjust reaction times based on flow rate and application variables. This is achieved by adjusting the amount of 15x accelerator accordingly in the range of 2-20%. For gushing leaks, 20% accelerator solution will provide immediate results while most common crack leaks are repaired with a 5% solution. This is roughly 7oz. of Foundation Armor 15x per 1 gallon of Foundation Armor Polyurethane Resin. After mixing, the polyurethane is ready for injection.
Fully examine the existing site conditions to ensure that all associated work can be performed without removing or relocating existing utilities, structures or structural members.
1) Wear adequate protective gear and goggles at all times, and follow data sheet and MSDS Instructions.
2) Thoroughly clean the face of the crack or joint by wire brush, disc sander, pressure washing, or similar. It is recommended to inject into the cleanest substrate possible for optimal results.
3) Identify the drill hole spacing and depths.
- Spacing: Drill holes should be 6-12” inches apart (6” for hairline and 12” for wider cracks). Alternate positioning from left side to right side as you move along the crack where possible.
- Depth & Angle: Drill at a 45° degree angle where possible to intersect the wall/floor joint interface halfway through the thickness of the substrate (e.g. 4” deep for 8” thick slab) Drill straight into the crack for concrete thickness below 4 inches. Drilling depth should be half the thickness of the concrete member.
4) Before installing mechanical injection ports, you must confirm that the hole is accepting water. Add water into the hole. If the hole is accepting the water, the water should enter in through the drilled hole and escape into the crack. If the hole is not accepting water, you 1) may need to drill deeper, or 2) the crack is directed into the opposite side (which means you need to drill from the opposite side of the crack and water test again. (Note: Do not inject water using the pump included in this kit. The polyurethane is water activated and it will cause pump failure if there is water in the pump).
5) Once you have confirmed drill holes are accepting water, install mechanical injection ports and secure in place. These packers have a threaded shaft with a rubber base. Following insertion, tightening of the threaded shaft will compress the rubber inside the drill hole, resulting in a compression seal through which you will inject the polyurethane resin.
6) Begin injecting from the lowest packer. Under proper pumping conditions, the following signs should be observed in the order listed:
(a) Water displaced from crack/joint by the resin (if you have a dry crack, add water to the crack)
(b) Water and resin mix (foamy) appearing at the crack/joint area
(c) Pure resin from crack/joint
If the joint surface exhibits immediate free flow of resin while working the first packer, pause for a few minutes. In most cases the resin will react fast enough with the water and expand rapidly. The resulting resin product will heal the joint and provide a surface seal to contain the material to follow. The applicator/contractor is responsible for estimating what duration time is adequate for grouting the voids and is responsible to prove that the void is full by attempting to inject each port to refusal.
Once the applicator/contractor is assured that the resin has reached the next injection packer or has sufficiently stopped the water as evidenced by the grout oozing out of the joint area, he should shut off the resin flow and disconnect pump pressure line and proceed to the next packer. Follow the injection process for one to three packers, the applicator/contractor shall return to the first packer and attempt to re-inject it again. Some of the packers will take more grout, filling up more of the crack/joint area and creating a higher density void filler and water stop. The applicator/contractor shall continue this procedure until refusal.
7) Make sure the above procedure has been repeated until the entire length of the rack or joint is sealed.
8) After allowing the material to fully cure overnight if possible, packers can be removed by loosening the shaft. Some applicator/contractor leave the rubber base in the wall and then patch the drill hole while others remove the entire packer prior to patch. In some remote injection applications packers even remain in place permanently. This is applicator/contractor preference. A final cleanse of the face of the crack is necessary to remove cured product via wire brush, pressure washing, etc. The substrate is now ready for final finish to applicator’s/contractor’s intention.
9) Flush all dispensing equipment initially with a small amount of solvent such as xylene or acetone to cut the product (if permitted on the job). Do not use solvent for the final flush as it will diminish the life of your equipment drastically. Do NOT clean with water!!! Store for next use.