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ACI quote - Let's talk about permeabiltiy.
11-19-2012, 12:29 PM,
#1
ACI quote - Let's talk about permeabiltiy.
From ACI-“From the materials standpoint, concrete durability is closely linked to concrete micro-structure, more specifically to its impermeability.”

An interesting concept. An objective look at concrete technology seems to lend credence to this statement. Where does concrete's permeability come from? Free water...more specifically the effects of free water.

Let's take a look at admixtures. I don't believe there is a yard of concrete today from a professional ready mix plant that does not have some sort of admixture in it. When you look at that fact objectively, almost every one of those admixtures is trying to compensate for or eliminate the effects of free water.

We have different mix designs for different applications, each application with it's own set of challenges, but the fundamental cause is free water.

The Romans knew concrete 's permeability was a problem long before ACI. They were using things like blood and animal fat to combat this issue.

Concrete has one flaw. It's permeability. It is a battle that has been waged since concrete's infancy and we continue to fight that same battle today.
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11-19-2012, 01:32 PM,
#2
RE: ACI quote - Let's talk about permeabiltiy.
Are we limiting the discussion to slab on grade concrete without a proper vapor retarder?

Or are we discussing elevated slabs and slabs with a proper vapor retarder?

And did the ACI statement you quoted refer to a specific scenario?
JD Grafton
Concrete Answers for Flooring Problems
[email protected]
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11-20-2012, 06:06 AM,
#3
RE: ACI quote - Let's talk about permeabiltiy.
(11-19-2012, 01:32 PM)CC Solutions Wrote:  Are we limiting the discussion to slab on grade concrete without a proper vapor retarder?

Or are we discussing elevated slabs and slabs with a proper vapor retarder?

And did the ACI statement you quoted refer to a specific scenario?

The discussion is only limited to concrete. A vapor barrier/retarder does not make concrete more or less permeable. Elevating a slab does not make it more or less permeable.
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11-20-2012, 06:45 AM,
#4
RE: ACI quote - Let's talk about permeabiltiy.
I agree, but both eliminate future sources of moisture and reduce the risk to water of convenience introduced in the mix. Who cares how permeable a slab is when it is poured in a pan and capped by a welded rubber floor?
JD Grafton
Concrete Answers for Flooring Problems
JGrafton@cc[email protected]
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