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**EXPERT Advice Needed** - VERY Moist Slab With LOTS of Vapor! What to do?


Thank you for your kind words.

I have a call into our consultant re ASTM 309-07. As I pointed out to you silicates cannot be divorced from concrete, as concrete itself depends on silicate reactions CSH to produce the binder paste.

The issue is how they are employed and what is the end result. We all know Meta Silicates (unreacted silicate) create bonding difficulties for coatings. Why? because the upper densified layer, although harder and favoured as a warehouse floor hardener, does not control moisture transmission but can encourage it. But these have their use.

I am trying to get my mind arround your comments on VT as to why a technology that achieves in concrete, after the fact, what could and should be standard during batching is considered detremental by the adhesive manufactures. Seems they are allowing past poor silicate practice to dominate their thinking.

I have over the years tried (as flooring contractors who we solved their VT issue encouraged us to) to get this accross to their suppliers but I stopped trying. I have my clients who refuse concrete without the assistence of ICD hydration (we just had 3 days of suspended slab meetings and are now on the spec). Will not drop names.

Think of a floor concrete as a hard sponge, water or vapour can freely pass through its pore structure (thats what sponges are for) but why should this be so for concrete. Standard OPC concrete is pourous, even with low W/c and during the drying stage, the exiting excess mix water (which can be controlled by good hydration) is anything over 0.2 W/c. This will exit and carry with it not only residual Ca(HO)2 but if on grade (with or without a VB) other deleterious salts/contaminants. Yes there are all kinds or drying processes but the concrete can manage this itself if allowed.

None of our industrial slabs have VB's under them nor do we need drying assistence.

Now we havn't really changed the concrete, we have advanced the utilization of the two key ingredients, the cement and water so as to naturally enhance the hydration process. Yes we have used a silicate based solution ( Roman and modern engineers use pozzolans) to react with the cement. ICD takes the hydration reaction to a level that simply using powders cannot. I sent you SEM's of this fact.

Surface applied ICD silicate solutions are no different than the admixture ICD solutions except they have additional assistence for migration deep (not 1/8 to 1/4") into the substrate. Testing confirms that no residual meta silicates were evident after SEM evaluation. This promted the president of the testing lab to write " This is a fundamental advance in the science of concrete"

We have no harm testing and letters (unsolicited) from the Engineer who got his masters designing the concrete for the Kobe bridge in Japan and the ex QC engineer LaFarge now an independant where he summed up his dismay at how the industry has prefered inefficient admixtures over hydration technology.

Should not have said it was my last post.

Best regards.


Messages In This Thread
RE: **EXPERT Advice Needed** - VERY Moist Slab With LOTS of Vapor! What to do? - john macdonald - 11-04-2011, 02:54 PM

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