All the manufacturers use vapor pressure as the benchmark on concrete, so how do the moisture percentages of meters relate? Has anyone come up with a good correlative scale, or do we just keep comparing readings to Chloride tests till we figure it out?
I'm looking at installing cork in a room where the concrete has between 3% and 4.5% moisture. We are going to put down a sealer, but it is only good for up 6lbs pressure. Am I good to go?

I don't know what kind of sealer your going to use, but it is best to use an adhesive / sealer system from one manufacturer.

One such system I recommend is from Taylor adhesives. It is very impressive! To say the least.


http://www.wftaylor.com/newlock.php



This is their 2086 adhesive for cork, to use as a system with their 2042 X-Treme Concrete Sealer, for concrete moisture problems.

Thanks for the info on the sealer but, for warranty protection, we're going to go with Expanko's own sealer. We are on an island where getting 1 rep out to look at a problem is difficult, getting 2 over to argue who's at fault is impossible. Hopefully Expanko's is just a relabeled Taylor.

Any ideas about moisture content vs vapor pressure? You would think that someone would have graphed it out by now. I'm still hoping.

They are different types of measurements. I really doubt there is a reproducable crossover between the 2 methods.

It is a qualatative versus quantitative sort of thing.

Some manufacturers are giving acceptable values for encounter meters now. I can't name them off the top of my head,but I have read them more than once.

Your good to go if....the manufacture says "use two coats" you better use two coats.

Some topical sealers need two coats. Other sealers designed to penetrate require the floor be shotblasted and or scarified or else the sealer will sit on top of the concrete and create a bond breaker.

Drop a couple CaCl tests afterwards before installing to be sure the sealer is working. Only testing before hand is not sufficient.

You said its hard enough to get one rep never mind two, If you use a manufacturers full system ie. adhesive and sealer you only have to worry about one rep and who can they blame if you used the system correctly, personally I would go with Taylor.

Thank you gentlemen, it's all good info. I'll let you know where things end up when we get there.

You cannot use a pin/probe type wood moisture meter to measure concrete.

Tramex Concrete Moisture Encounter, is one meter.
Drilling the slab and installing a hydrometer, is another.
Calcium Chloride test is the industy standard, though.

I'm using a Tramex Concrete Moisture Encounter.
While I understand the differences between the 2 different kinds of measurement (percentage moisture vs vapor pressure), I just can't believe that someone hasn't charted the relationship between the 2 methods. I'm sure that concrete at a given percentage of moisture will exhibit roughly the same vapor pressure at a given temperature and relative humidty.
I'm just hoping not to be the one to have to try to chart it

Apparently there are people doing just that. However it is proving to be quite difficult due to all the varying circumstances.

In situ RH is the best regimen. ASTM 2071. Concrete RH is the best indicator of potential VE issues. CaCl tests are easy to screw up. Even if they are done properly,they fail to predict the likelyhood of future emissions.