The New Tramex

[CC Solutions]

Ha ha... I did follow one 'expert consultant' who drilled completely through the slab on grade and then set his sleeves at the proper depth.

And did I ever mention the independent tester who drilled through the 12" thick suspended slabs so he could push his Wagner's through and catch them from below and then re-use them? I couldn't figure how my readings were higher using the same probes until I figured out his holes went through to the lower level and had dry air blowing through them.

[Ernesto]

I hit a water line nailing tackstrip once.

Ever worry about hitting a post tension cable?

[CC Solutions]

When taking core samples I have hit them... That and rebar. Last job had rebar on 6" centers, so only 5 3/8" between bars and we were pulling 4" cores.

[Ernesto]

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

[CC Solutions]

We drill with dry diamond thin wall core bits.

[Ernesto]

Ya know CC, I've always wondered about those core samples. Was it for a psi test or what?

[CC Solutions]

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!

[Floorguy]

My Tramex Concrete Moisture Encounter, is excellent at finding internal plumbing leaks "Hot Spots". I'll put it up against almost anything.

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From the core you can also see how big the capillaries are, to see if the cement man, messed up.

[eaadams]

(01-12-2011 10:12 AM)CC Solutions Wrote:  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!

This is the only way I know of to check for the presence of curing compounds per ASTM F710. Can't trust what the GC says, cant trust original specs, can't even trust MSDS on site.

[CC Solutions]

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.