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TIL a contractor taught me the 3 tap rule for concrete testing
I was pouring a driveway off South Lamar last spring and an old-timer walked up, tapped my test cylinder with a hammer three times, and said 'if it rings clean you're good, if it thuds you got voids.' Now I tap every batch before I let the truck leave. Anyone else have a weird field test that saves them time?
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gracec1616d ago
That's a pretty common field test actually, the three tap thing has been around for decades. One thing though, the ringing doesn't mean the concrete is good by itself. It just means the cylinder has good density and no big air pockets near the surface. The real test is the compression break at 7 and 28 days. The tap is just a quick check to catch obvious problems before the truck leaves. I've had cylinders ring perfect but still come back below spec because of water ratio issues or bad curing. So use it as a helper, not a guarantee.
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daniel14016d ago
No way, he just walked up and did that? That's wild... I'd be standing there with my mouth hanging open watching some random guy tap on my concrete like he owned the place.
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parker_palmer4415d ago
The thing nobody mentions is the acoustic part. If you tap a cylinder with a hairline crack that you can't see, it'll still ring clean because the sound travels through the solid parts just fine. I've had it happen on a pour where the form got bumped and we didn't catch the crack until we stripped it. The tap test is good for voids but it won't save you from structural weirdness.
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