Digging out your crack

Post date: Sep 05, 2013 9:36:4 PM

Recently on a jobsite, I identified a crack in the top of a drilled shaft.  In my opinion, this crack was likely the result of limited contamination in the concrete of the drilled shaft.   Likely the crack was exposed when a workman hammerdrilled the top of the drilled shaft to increase the roughness.  The crack was crescent shaped, and did not coincide with the rebar cage, nor did it present on any surface but the top.  The crack was as wide as 1/8" and tapered to nothing along its 18" length.  That 1/8" portion was of indeterminate depth, but had loose concrete that could be removed by hand.  Unfortunately, according to the specifications on the job, any cracks require epoxy injection repair.  So my client and I briefly discussed different types of epoxy and who was qualified to do this repair.  

The next time I visited the job site, I asked when they were going to repair the crack, as I'd like to be there to observe it.  I was told that they had hammerdrilled the crack out of the top of the drilled shaft.  I asked to see it, but the grade beam formwork was already up and I couldn't get a great picture of it.  However, in my non-official opinion, they did indeed chip out all the crack, to a depth of about 4" along the length of the 18" crescent.  They will fill the new grand canyon crack when the grade beam is poured on top of it.

So, I present this as a new Outlier solution.  In the right circumstances, a crack can be chipped out.  Who'da thunk it?