Walgreen's Slabs

[Ernesto]

This leads to another thought. If there is an issue with the floorcovering in question as I mentioned above thread. And the slab has equilibrated as much as it's going to with said floorcovering on it, then why should one have to record rh readings at the required depth. Much of the F-2170 science is all about before the app, not after the fact.

I'm thinking that a 1 1/2 in hole for a 4 inch slab is going to tell you just as much if the slab is ten inches thick.

How about a sensor that reads in 1/2 inch increments all the way to the top?

[eaadams]

I had the same request from a customer this month. They are worried about slab equalization and reverse curl.

How does one tell when a slab has hit equilibrium?

I don't know. the engineer's recomendation was literally to 'hope for the best and pray to god' oy..

[Ernesto]

Obviously he wasn't a reverse curl slab engineer. But thats a little out of my comfort zone.

I want a sensor that tells me whats going on from top to bottom, in certain increments, even whats coming out the top. How hard can that be?

[eaadams]

Well you can do multiple tests at multiple depths and then use a hood test and the lightweight concrete hockey puck.

[Ernesto]

(10-13-2011 06:46 PM)eaadams Wrote:  Well you can do multiple tests at multiple depths and then use a hood test and the lightweight concrete hockey puck.

Yes, I figured that...but how long would that take?

If the smart sensors were to be extra super smart, they could tell us all that. I envision a sensor that can do that. I have a design in mind.

Call me old school, I still want to know whats down under, whats coming up to the top and whats coming out of the top. No slab design is the same, so therefore no MVER will be the same.

Ok so instead of 1/2 inch increments we have a sensor with just 4 increments. You should be able to set the depths before placement before insertion accordingly. The depths would be, first the standard depth, then the middle depth, then the near top depth of 1 inch or so and then the surface.

I think I need a new topic.

[CC Solutions]

Wow you guys are over thinking this....

Yes moisture equalization will occur over time. When it occurs, the RH in the slab will be equal to what it is at 40% (for a slab drying from one direction ... just always have to plug that disclaimer in there ) so theoretically, and even lab provenly, no matter where you measure the RH on an equilibrated slab, you will read the same RH.

Now, if the flooring is relatively new and has changed in recent years, or if there is a permeable floor covering (VCT does breathe a bit) the moisture in the lower regions of the slab can be higher, especially of the vapor retarder is compromised or missing altogether, or if the slab has not equilibrated yet. You still read at the 40% depth (FASDFODO) to get your RH.

You can take readings at all different depths but what will that tell you besides the slab still hasn't equilibrated? So what if it's 99% at the bottom and 60% at the top? I don't see how you will use that knowledge to change the way you follow the book.

[Ernesto]

No no no, if the floor has been on there for a good length of time the slab has equilibrated enough .....even if it's ten inches thick....to get a good enough snapshot of what the rh is at 1 1/2 inches as it would be @ 4 inches.

Especially if the adhesive is oozing out the seams in the vct as it is now. Is there documented study to back up your assertion? It would be nice to have some testing done about after the fact. Your thought process is stuck on new slabs.

There's been people there already. I saw evidence of another rh test, NOT a Rapid Rh test but those other ones I guess everyonhe had a pow wow about it but now I'm going in with the best rh test.

Course it could be one a a few other issues. I see these guys go in and flood the vct to strip it after installation, then wax it trapping water in there and they don't roll it either. Could be a ph issue as well.
Maybe the installer just threw down the vct over wet adhesive then the floor guy stripped it and so on and so on.

But there is also major road work going on out on the street, new water lines..... = higher pressure, curbs drainage, blacktop the whole bit.

[CC Solutions]

(10-14-2011 11:54 AM)Ernesto Wrote:  No no no, if the floor has been on there for a good length of time the slab has equilibrated enough .....even if it's ten inches thick....to get a good enough snapshot of what the rh is at 1 1/2 inches as it would be @ 4 inches.
If it has equilibrated. Again, a porous floor on a slab with no vapor retarder can be very wet down low. It will take time to equilibrate.

Especially if the adhesive is oozing out the seams in the vct as it is now. Is there documented study to back up your assertion? It would be nice to have some testing done about after the fact. Your thought process is stuck on new slabs.
I'm talking old slabs here. Remember my Las Vegas example that was on wet soil but dry as a bone on top. Slab was 20+ years old. They put sheet vinyl on and instantly had water problems.

There's been people there already. I saw evidence of another rh test, NOT a Rapid Rh test but those other ones I guess everyonhe had a pow wow about it but now I'm going in with the best rh test.
Don't worry about those before you. You are much smarter than they are. You will know what's wrong. Getting the owner to pay for it could be another issue.


But there is also major road work going on out on the street, new water lines..... = higher pressure, curbs drainage, blacktop the whole bit.
Here's where you and I tend to disagree. I don't care what the water table is, what the drainage is like, I don't care if the building is floating on the sea. If there is a good vapor retarder the slab will not be affected by the water. If there isn't, I don't care to even test it, just mitigate it.

At this point if you find any water anywhere you have to mitigate. The slab is old. How else can you possibly guarantee never another failure?

[Ernesto]

I'm not mitigating anything. I am hired only to do moisture tests. Obviously if it is a moisture issue the slabs moisture has equilibrated ie adhesive ooze.

Could also be a leak. New water lines.......I wonder if this issue has coincided with the new water lines.

[Ernesto]

OMG I totally forgot about it could have been a dewpoint issue at the get-go! heh heh