How are you drilling out those cores CC?
I was working near a bathroom when the plumbers (new construction) started jack hammering the slab that had post tension cables in it. I left early that day. lol
We drill with dry diamond thin wall core bits.
Ya know CC, I've always wondered about those core samples. Was it for a psi test or what?
We must do core tests for a variety of reasons. Usually we look for deleterious constituents in the concrete which would adversely affect the bond of our mitigation system. In other words, if there's stuff in the mix or surface applied that may cause an adhesive or epoxy to not bond as expected.
We also look for evidence of ASR (Alkali silica reaction) which would preclude or at least severely change our course of concrete remediation.
After a full battery of tests, we can be reasonably assured we are taking the proper course of action to repair the concrete so the end user never has a failure.
But one of the most useful and overlooked tests anyone can do is to place a drop of water on the slab and watch it. It should be completely absorbed in a minute. If it beads up and sits there a red flag should go off!
02-03-2011, 12:27 PM
(This post was last modified: 02-03-2011, 12:32 PM by Floorguy.)
My Tramex Concrete Moisture Encounter, is excellent at finding internal plumbing leaks "Hot Spots". I'll put it up against almost anything.
From the core you can also see how big the capillaries are, to see if the cement man, messed up.
While a drop of water being absorbed is a pretty decent field test, it is not qualitative and I sure wouldn't bet my reputation on it.... please don't take this as an all inclusive test for contaminants!
Unless an owner or GC can certify (or is willing to certify) the slab as contaminant free I will pull cores and conduct Ion Chromatography, Infrared Spectroscopy and often X-Ray Diffraction analysis on the samples.
Even then, lack of contaminants on those small 12 square inch core areas does not guarantee that the entire slab is contaminant free. It is a good start though, and with careful review of the slab and proper preparation, we can be reasonably assured of correct diagnosis and remedial action.