About a year ago I was on a project where we had to retrofit a large number of hold-downs by epoxying threaded rod into holes drilled in an existing concrete foundation. An inspector was there when we installed the rod to verify that the holes were clean, we used enough epoxy, and that we used the kind of epoxy specified by the engineer. He said he routinely visits sites where the holes aren’t clean enough—then he showed me a tool that makes it easier to do the job right. It’s called the Vortabrush, an extension for a compressed air gun with a brush around the end of it. It allows you to brush and blow the hole clean in a single operation (video below).
I bought a Vortabrush and using it is faster and easier than cleaning holes the traditional way—which according to Simpson means blowing the hole with compressed air (minimum 80 psi) for at least four seconds, running a brush up and down it at least four times, and then blowing it for at least four seconds more. If the hole isn’t clean enough the epoxy connection between rod and concrete will not meet the design strength. With the Vortabrush we can brush and blow a hole clean in about five seconds.
So in about half the time you get a cleaner hole. This might not sound like a big deal and really it isn’t if you only have a couple of holes to clean. But on some commercial sites you might have to do hundreds.
The Vortabrush is available in diameters from 5/8 to 1 1/2 inches and should be sized to fit the hole. We bought one from the company’s website for $40 and put it on a standard blow gun. When I get a chance I’m going to buy a pistol grip blow gun and put the brush on that because it gives a better angle and you don’t have to bend your air hose as sharply.
Since buying the Vortabrush we’ve started blowing the debris out of holes drilled for wedge anchors. An inspector told me that this is starting to be required in certain jurisdictions. It only takes a few seconds, so why not?
In the video below Kyle Davis uses the Vortabrush to clean holes prior to the installation of expansion anchors. The process would be similar for epoxy anchors—except that an inspector would be present to observe and Kyle would spend a little more time blowing them out.