Treatment Plant Project: A Closer Look at Injection Resin

The process of Injection Resin was used to repair cracks in the bunded area of the treatment plant, where water was percolating through construction joints. On this occasion a hydrophobic polyurethane foam was used which is very fast acting on contact with water and can halt the flow of water quickly and prevent future leaks.

“With any refurbishment programme, surface preparation is key. The concrete must be cleaned to remove contaminants. The crack itself is blown off with clean dry air so that resin can flow freely into and along the cracks. Resin is then injected under pressure either into inlet ports that have been stuck to the concrete surface over the crack or through holes drilled to intersect the crack.

Injection is undertaken using a pump to apply pressure. On larger projects the pump may incorporate measuring and mixing equipment to deliver the resin thoroughly mixed together. For smaller projects injection is undertaken using a hand pressure gun.

If the crack needs to be structurally repaired and the area needs to be as strong or stronger than the concrete around it an epoxy would be used. Epoxies for crack injection are available in a range of viscosities and have a compressive strength that usually exceeds that of concrete. Epoxies cure very slowly, generally taking hours to harden which can allow time for the epoxy to flow into the smallest of crevices.

If the crack needs to be repaired to prevent water leakage or the crack is actively leaking, a polyurethane would be used. If there is concern about material leaking out the back of a crack, polyurethane foams should be used. They begin to harden and foam on contact with water. This reduces the chances of the material flowing out of an injected crack while still in liquid form, and even if some does leak out, the foam will fill the void.”