Here it is. My favorite topic. Why? Because I have seen and heard some really stupid things concerning this. It is my pet peeve. It separates the technicians who care from those who are only going through the motions. And quite frankly, it can be the difference between a successful outcome and dismal failure - or at the very least an expensive call back.
When you drill holes you create concrete dust. The hammer drill bit literally chews up the concrete. Most of it comes out of the hole and falls on the floor. However, a lot of dust is left behind inside the hole. If it is not properly flushed out then it will mix with your polyurethane injection resin and make a thick paste. This thick paste can be forced into the crack and prevent the clean resin from reaching deep into the crack where it is needed. Most of the time you won’t even realize you have a problem. But there it is nonetheless. Waiting for the right conditions to allow water to seep back through the crack you thought you fixed.
How to avoid this? Simple - flush the hole out from the back using a very cheap flexible hose that attaches to your flush pump (you did bring a separate flush pump didn’t you?). Start at the highest hole and work your way down until clean water is flowing out of each hole.
Spraying water at the face of the holes may make it look clean, but it is not. There is still dust deep in the hole. Filling a water bottle up and squeezing it so that water shoots part way up the hole is not good enough. You have to have the water exit your hose at the back of the hole. This is the only way.
Exceptions? Of course there are. If you pull the drill bit out of the hole and water gushes out behind it in a steady stream you can skip this step. Otherwise, make sure you bring a flush hose with you. It has to be small enough to fit inside your drill hole. We make it easy for you. We make one and sell it for cheap (so don’t blame us if you get to your jobsite and don’t have one).
This is so basic it is silly. However, I have seen experienced technicians do the water bottle trick and try to explain that it is sufficient. I’m happy to report that those guys are working for your competitors now. Just make sure your guys don’t get lulled into laziness and skip what just might be the most important of these five basic steps:
- Drill the hole
- Flush the hole
- Install the ports
- Flush the crack
- Inject the resin
Next up, installing the ports!
Click below to read the previous articles in this series if you missed them:
5 Steps of Concrete Crack Injection - Overview
5 Steps of Concrete Crack Injection - 1. Drilling Holes
5 Steps of Concrete Crack Injection – 1. Drilling Holes (Continued)
Click below to read next articles in this series:
5 Steps of Concrete Crack Injection – 3. Installing the Ports
5 Steps of Concrete Crack Injection – 4. Flushing the Cracks
5 Steps of Concrete Crack Injection – 5. Injecting the Resin
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