Injection Crack Repair: Which Technique to Choose?
In order to repair cracks on the walls or foundations of your home, it is possible to use two injection techniques: high-pressure and low-pressure injection. These two techniques used by Groupe Fissure Expert Fondation allow for the quick and durable repair of your foundations.
High-pressure injection
The equipment used has been specially configured by a highly trained technician to infiltrate any type of crack , in order to achieve a 100% efficiency rate. The technician’s job is to regulate the flow rate as well as the pressure of the liquid in the crack in the concrete, for a lasting end result.
In the residential sector, the strength of concrete on a foundation wall or floor (flooring) is approximately 20-25 MPa or 2900-3625psi. In the event that the pressure cannot reach a minimum of 2500 psior exceed 3500psi, you will get a job of poor quality and known inefficiency.
It is important to remember that too much flow and pressure will create micro-cracks in the concrete and around the injection port through which the liquid will escape instead of seeping into the crack.
The following photo shows very well what the injection method consists of. It is characterized by the installation of mechanical metal injection ports at an angle of 45 degrees to the crack. The purpose of this technique is to introduce the injection polyurethane from the middle of the crack. This ensures that the crack will be infiltrated all the way to the end, from one side to the other.
Low-pressure injection
The low-pressure injection method involves introducing a liquid at very low pressure into a narrow crack (greater than 1/16″ or 1.5 mm).
The equipment required for this type of injection is simple: a caulking gun, a dual-cartridge gun or a handheld sprayer. However, this injection technique requires some practical experience in order to be effective.
Low-pressure injection relies more on the principle of gravity rather than the pressure principle itself, as the pressure used is around 50psi.
This technique is particularly suitable in the case of epoxy injection for non-active cracks , inherent in structures that must preserve their architectural elements: parking slabs, viaduct pillars, lamppost bases, etc.
The following photo is a good example of low-pressure injection :
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For any question or repair on the cracks in your home, contact one of our experienced technicians at Groupe Fissure Expert inc.
Limitations of Low-Pressure Injection
While this method is effective in many situations, it has some limitations:
- The method is not well suited to repairing cracks on a concrete foundation wall (foundation);
- The crack must have an opening of more than 1/16″ or 1.5 mm. Otherwise, it will be impossible to inject the sealant into the narrowest part of the crack. Generally, this is where the water seeps in;
- There must be no water infiltration at the time of the work.
The following photos show very well what the injection method consists of. It is characterized by the installation of plastic surface injection ports , placed directly on the crack.
Rubber low-pressure injection port
Plastic Surface Injection Port
Installation of Plastic Surface Injection Ports
Low-pressure injection with a single caulking gun
Low-pressure injection with a dual-cartridge gun
Low-pressure injection with handheld sprayer
Low-pressure injection completed
Failure of low-pressure injection, in less than a year
Failure of low-pressure injection after 2 years
Failure of low-pressure injection after 3 years
For example, consider having your cracked foundation inspected so that a professional can determine the type of injection to be performed. Having your building’s cracks repaired helps prevent water infiltration. Do you need an experienced technician for high- or low-pressure injection into your foundations? Contact one of our technicians in Quebec for your crack repairs!