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Low-Pressure Injection for Residential Foundations with Polyurethane Injection

When repairing a foundation wall with an epoxy or polyurethane foam polymer, it’s best to inject the material at low pressure. To ensure that a crack injection is effective, the liquid polymer must be gradually introduced into the crack at low pressures (20 to 40 psi). This method may take longer than other filling techniques, but it allows the applicator to monitor the injection process and ensure that the crack is completely filled. Most crack repair failures result from incomplete injection of the crack.

At pressures less than 40 psi, the liquid does not have enough pressure to overcome the force of gravity and circulate. This means that the epoxy or polyurethane will only move upward in the crack when it is applied and allowed to cure completely. Therefore, low pressures ensure that cracks penetrate more thoroughly. The applicator can also monitor the progress of filling the crack by observing the filling material and watches for the liquid to begin coming out of the port above the one being injected.

At pressures above 40psi, the liquid has enough energy to overcome the force of gravity and will flow downhill. It can rise from one port to another without plugging the back end of the crack, which is typically narrower than the front end. High-pressure injection is more effective for repairing cracks in thick-walled structures or stopping a high volume of water flow, such as dam repairs.

Injecting a crack properly first requires applying all the injection ports and making sure the crack is otherwise sealed. Inject polymer at the lowest port on the wall, and then continue injecting at 20-40psi until it seeps out of the port above it. That’s the visual sign that the crack has been filled from front to back. After plugging the first port with the provided cap, move up to the next port and repeat the procedure until you have filled all of the cracks with epoxy or polyurethane.

The purpose of this process is to fill the crack completely with epoxy or polyurethane. The Jake injection tool is a spring-assisted dispensing tool that helps you control injection pressures and the polymer is injected into a mold by the force of a compressed spring. In addition, air-powered tools allow for dual-cartridge dispensing and control of injection pressure. It is important to note that using other conventional dual manual tools may result in injecting at pressures much higher than desired, which can lead to incomplete filling of the crack.

For any polyurethane injection work, contact Le Fong Building Services, the number one waterproofing company in Singapore.