Epoxy injection is one of the best ways of repairing a cracked concrete surface. Generally, it entails establishing entry and then injecting epoxy under high pressure. But it's not that simple, you need to do the job comprehensively for the epoxy to remain effective. Before rolling up your sleeves, it's also worth noting that epoxy injection doesn't work on all kinds of cracks. Actively leaking cracks for instance, would really decrease the epoxy's effectiveness. Additionally, this technique doesn't work for large cracks. So if you've got a narrow crack you want to fix, or you simply wish to learn about this process, then here are the steps involved.
Clean the Cracks
The main reason for doing this is to prevent any contaminants from reducing the adhesive properties of the epoxy. Flush the crack with water or vacuum it to get rid of tiny concrete particles or contaminants such as oil and grease.
Seal the Surfaces
Sealing is a technique used to ensure the epoxy doesn't leak out once it's injected into the crack. It's important particularly when the epoxy is going to be injected at high pressures. Materials such as polyester and epoxy can be used to seal the crack. Applying the sealant is simple: all you need to do is smear the paste over the crack and give it a couple of minutes before injection. It'll eventually harden and become impermeable.
Install Entry and Venting Points
During sealing, you could also install your entry ports. This is the point through which you'll inject your epoxy. You could choose to interrupt the sealing to leave small gaps that would allow direct injection of the epoxy. You can use this technique if you've got a gasket that covers up this unsealed part during the injection process. For V-shaped cracks, you can drill a hole that intercepts the crack at the apex and use the hole to inject the proxy.
Mixing the Epoxy
Here's the part where you go back to your manufacturer's manual. You need to ensure that you mix the epoxy right because different products have different specifications. A mechanical mixer would be a good help to ensure the resulting mix is properly made.
Inject the Epoxy
You can go for hydraulic pumps, air-actuated guns or even paint pressure pots to assist in the injection. Remember, increasing the pressure doesn't necessarily mean an accelerated injection rate. Select the pressure carefully, it should be just enough to reach into the unseen parts of the crack. Start pumping the pressurised epoxy from one end of the crack till it slowly flows to the other. You need to ensure that there is no leakage outside the crack. Once the epoxy cures, you can remove the surface seal.
For more information on concrete repairs, talk to a professional.