Taking the heart out of a concrete column... with a spoon

posted Jan 26, 2016, 12:12 PM by Amy Stone
Today's post is more informative than the usual juicy tale of Engineering Exploits.  I'm often asked fairly esoteric information, such as 'how long does it take to drill a core in concrete'.  Well, believe it or not, I typically do not witness this sort of thing.  I request the test, and read the result, but I don't go out there and witness it.  So, here I got the chance to witness the process.  I carefully recorded the following answers to your burning questions about drilling cores.

How long does it take? From the driller parking the truck to driving away: it took 2 hours to drill 4 cores, each 6 inches deep

structural observation
How big is the apparatus?  See above picture... It's that big.  
How loud is it?  You need earplugs if you are going to be within 20 feet, but it's not nearly so loud as a jackhammer.
What does the core look like?  Well, kind of like a beer can made out of concrete.  Until the lab cuts off the bottom, it's rough as shown in the picture.  The driller actually drills the sides and then snaps off the bottom.  

empty hole
Finally, will the hole be patched?  No, actually.  The company that drills doesn't patch.  If it needs to be patched for aesthetic reasons, then you need to call a concrete contractor.  
Is it as smooth as it looks?  Yes.  The inside of the hole, and the outside of the core are smoother than wood grain.
And those, Ladies and Gentlemen, are the most common questions I get about cutting into the very heart of concrete structures.
I look forward to hearing from you!