CC test. To grind or not to grind?

Flooring Forum - DIY & Professional

Help Support Flooring Forum - DIY & Professional:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

highup

Will work for food
Supporting Member
Pro
Joined
Mar 6, 2011
Messages
18,109
Location
,
Taylor kit has no mention of grinding the concrete surface prior to testing.......... so should I?
A testing company did a CC test on a slab and reported the results at 7.4
I went to the job location yesterday and noticed they did some light grinding over about a 2' square area. The dome was obviously set in the middle of that area. I have no idea what brand of testing kit they used. There was a dome residue outline left on the concrete like the square dome the Taylor kit provides. I assume different kits are all about the same.

I recall reading somewhere that you do the grinding one day, then set the test the following day to allow the concrete to "equalize" or stabilize in the area that has been ground.
I know for fact the testing company that did the test on this slab, set the dome immediately after the grinding was done. I know this because at 11am I told my contact at this job site that they must do this test......... Three hours later, I was told the tester had been contacted, he had arrived, and the test was started....... so no way was there any waiting time after grinding.

I bring this up, because I was planning to do a test myself. If my test shows nearly the same as their test, it might give me a bit more confidence if I were asked to do one.

.....so, should I grind, or not grind? Taylor makes no mention to do so......... their instructions pretty much say "set it and forget it" (for 72hrs)

The area to be tested has no sealer or curing compounds on it. The surface is not shiny nor smooth and was never troweled, because the area to receive flooring is a 13 foot by 16 foot depression created with a 2X6 and plywood form.
This slab was water cured, for probably for over a month. The slab is about 2 years old now and has been enclosed for a year or so.

Questions are:

Grind, or not to grind?

If I grind........... should I wait a day to place the test kit? That is not a problem time wise as the location is right in town. Test kit was free, and so am I, so money and time is not an issue.
 
grind it and let it set. But that is 208 sq. ft. I think you still need a minimum of 3 tests. They say 3 tests for the first 1000 and one for each 1000 after that.
72 hours isn't actually 72 hours. Its more like 60 something. But who am I, it's been a long time since I done one and things could have changed.

Daris
 
grind it and let it set. But that is 208 sq. ft. I think you still need a minimum of 3 tests. They say 3 tests for the first 1000 and one for each 1000 after that.
72 hours isn't actually 72 hours. Its more like 60 something. But who am I, it's been a long time since I done one and things could have changed.

Daris
60 to 72 hrs and then a little math quiz. Yes, 208 sq feet............ the other 10,000 sq feet is sealed polished concrete.
I don't know why Taylor doesn't mention grinding....... either on the box or on their site. I do recall seeing it tho. Thanks.
 
One would think that since the concrete has been down for that length of time the concrete would be dry?
Am I missing something?
One would expect it to be OK, but I don't know when the doors and windows were installed and when it was 100% enclosed.
This museum if I had to make a guess, sets less than 10 feet above high tide level, and less than 50 feet away from the actual bay. There is a vapor barrier under the entire building.......but still, I wonder. :eek:
I do not know at what point the large slab around this small area was polished and sealed. If it was sealed a long time ago, maybe the sealing hampered the drying process.

I might approach the museum about the insitu test. This is definitely a job that needs to have all the T's dotted and all the eyes crossed. :eek:
They are really pushing tho. Once the wood floor is in place, there is a very detailed map that will be routed into the floor.............. and that will take a long time to accomplish. They plan to open it in a couple of months, and this map-in-the-floor will be a major showpiece.
 
Last edited:
Wonder if there was a moisture problem wouldn't the area which was polished sealed have problems like the sealer coming off. I would imagine the concrete slab would have to have a low moisture content before the sealer was installed
What about doing the old quick test by laying a piece of vinyl on the slab for a day or so to see if there is a wet mark under the vinyl later
 
Last edited:
Had a 30 odd year basement in a house the other day where the existing vinyl had gone purple over a crack in the concrete
When I laid my paper pattern onto the concrete it took about 10 minutes for it to go wobbly
Another quick easy way to check concrete for moisture Not very scientific these ways but would make me to do a real check to work out the next procedure to prevent a flooring failure later

001.jpg
 
I might approach the museum about the insitu test. This is definitely a job that needs to have all the T's dotted and all the eyes crossed. :eek:
They are really pushing tho. Once the wood floor is in place, there is a very detailed map that will be routed into the floor.............. and that will take a long time to accomplish. They plan to open it in a couple of months, and this map-in-the-floor will be a major showpiece.

I feel the insitu testing is much more reliable. I really like the Wagner Rapid RH.

http://www.wagnermeters.com/flooring-moisture-meters/concrete-moisture/
 
Had a 30 odd year basement in a house the other day where the existing vinyl had gone purple over a crack in the concrete
When I laid my paper pattern onto the concrete it took about 10 minutes for it to go wobbly
Another quick easy way to check concrete for moisture Not very scientific these ways but would make me to do a real check to work out the next procedure to prevent a flooring failure later

Our black Scribe Rite black felt doesn't readily react to moisture or temperature. I have seen it wobble out a little like that though when left overnight or for a few days.

http://www.fortifiber.com/scribe_rite_black.html

What did you wind up doing with this moisture issue? How did they not anticipate the moisture with the old vinyl bleeding PURPLE?

Calcium Chloride in our neck of the woods is being relegated to the same dust bin of history as the "mat test". Nothing wrong with using it as a preliminary or supplemental survey but the real tests are done now with the Wagner RH System http://flooringsupport.wagnermeters...he-Rapid-RH-System-even-if-the-HVAC-isn-t-on-
 
Wonder if there was a moisture problem wouldn't the area which was polished sealed have problems like the sealer coming off. I would imagine the concrete slab would have to have a low moisture content before the sealer was installed
What about doing the old quick test by laying a piece of vinyl on the slab for a day or so to see if there is a wet mark under the vinyl later

This is the museum project that I mentioned earlier. I decided it best to begin a different conversation on the moisture emissions issues.

A slab has to be really wet for that mat test to happen. This slab is just ever so slightly 'moist'
We need to be sure of what will happen once the wood floor is installed and sealed on top. And believe me, this floor will be really, really sealed. If any moisture migrates slowly into the wood over time, the project will be ruined. This wood floor will be sealed on the top with 1/4 inch of clear epoxy, so any moisture at all, emitting from below will get trapped in the wood with no way out.
To eliminate moisture/expansion issues as much as possible, an engineered product has been chosen.

We're talking 22 bags of self leveling concrete, $800? ....plus the epoxy vapor retarder, plus the primer.
Then there's the wood. It's an expensive 13 ply 3/4 inch with a 6mm wear thickness........ say another $2000?
Adhesive another $200
The clearcoat of epoxy resin another $1500 to $2.000?
I am hoping the people involved in routing a map into this will be volunteer labor. I'm sure it will take a couple of weeks to do that part of the project once the wood is installed. Gonna be quite interesting to see how this all comes together.
 
OK, you use a Moisture meter and get a number. Will that number in any way relate to a CC test?

Can the reading be in anyway be compared to the CC test, or the insitu reading? ........or are all there methods so different that they cannot be compared?
 
Last edited:
Meter readings are not normally an accepted testing method by manufacturer's instructions. Meters can be a good indicator of where to place a test. Especially if there is a suspected trouble area.
 
ASTM F 1869-11 is the newest and I do believe you grind then set 24 hours later.
Even though I like the Rapid Rh test and do them alot for people I still like to know whats coming out the top. I even do CaCl over sealers. Bostik still reccommends CaCl over there's.
 
Meter readings are not normally an accepted testing method by manufacturer's instructions. Meters can be a good indicator of where to place a test. Especially if there is a suspected trouble area.

Thanks, that makes sense and helps a lot. Kind of an instant test to know when something needs further testing.
I guess it would be good to carry around a rubber mat, a concrete moisture meter, CC test kit and Rapid RH............. not necessarily in that order. :D
How about forgetting all them tests and just laying down some shower pan liner and calling it good. ;)

ASTM F 1869-11 is the newest and I do believe you grind then set 24 hours later.
Even though I like the Rapid Rh test and do them alot for people I still like to know whats coming out the top. I even do CaCl over sealers. Bostik still reccommends CaCl over there's.

Didn't know you could test after using a sealer.

How about after the self leveler is installed? I suppose in a week or two it's plenty dry to install the wood? SL will be 3/4" deep. Self leveler is gonna get installed by a UZIN company rep, with some assistants (me)........... I scored big time on arranging that one. :D
 
Last edited:
Well, it's getting interesting. I emailed the tech rep from UZIN about performing an insitu test. He said not to bother with the test. He said two coats of their epoxy emission coating can even be successfully applied to a 3 day old concrete slab. Wow.
He was quite confident in the products performance and voiced absolutely no concern about moisture migration.

He's driving 150 miles down here to oversee the project from applying the epoxy coating to pouring the self leveler. No charge for his labor. He's a company tech/rep and the company pays him to participate in this kind of stuff. Wow........ a weight has been lifted off my shoulders.


This museum sets right along side the bay. I'm taking a wild guess that the slab is 10 or so feet above high tide level. Most of our down down and water front is on fill. This area where the museum sets was a former mill, and dock area back in the 'early days'............ right up till the late 70s.

I contacted the company that mixed the concrete pour and was kind of freaked out at the vapor barrier. Sounds like it's nearly bullet proof. My biggest surprise is that the barrier is located over 3 feet below the bottom of the slab. :eek: Above the vapor barrier is compacted rocks and gravel, which sat for a year or more before they broke ground on the project.

The slab itself is over 8" thick at it's thinnest point. The heating system has been on since November.............. with those two factors alone, I bet the slab would probably have to dry for a couple of years to get to a more happy moisture level. Oh well, we got epoxy that's supposed to fix that.

The entire building is set on wide steel piling which were sunk down to bedrock. There were dozens and dozens of them placed. There are concrete "floor joists" 3 feet tall, and 2 or 3 feet wide which were poured on top of those piling. That might have been done in a single homogenous concrete pour........which might explain a one or two month water cure period.

Foundation and bladder end on.jpg
 
Last edited:
The vapor barrier should be directly below the slab, not the aggregate because of water intrusion into the aggregate it can become a doughboy swimming pool.
 

Latest posts

Back
Top