Plywood for concrete forms

[Larry Caldwell]

Somewhere I still have the ASTM manuals for procuring, testing and documenting test cylinders...they were on a required book list for a comprehensive class A GC's lic. in FL (circa 1970) they dictate from where and when test cylinders are to be taken as well as slump tests...

Yep, test cylinders have to be taken from the middle of the load and stored next to the structure so they undergo the same weather conditions.

 

[Streetcar]

View attachment 531891

Moss road
That always works for me

 

[Streetcar]

I think you should search a couple of terms...

Hydrophobic concrete
Hydroscopic concrete

:thumbsup:

Snobdds
What are you trying to explain with those terms.
Most concrete is hydroscopic( absorbs water)
Through addition ingredients concrete can be made hydrophobic( water resistant). In my line of work ,this is used in bridge decks

 

[Snobdds]

Snobdds
What are you trying to explain with those terms.
Most concrete is hydroscopic( absorbs water)
Through addition ingredients concrete can be made hydrophobic( water resistant). In my line of work ,this is used in bridge decks

Hydration and curing...it's all noted above.

 

[Streetcar]

Snobdds
Your explanations are as clear as if they came from your avatar

 

[John Fitzgerald]

Snobdds
What are you trying to explain with those terms.
Most concrete is hydroscopic( absorbs water)
Through addition ingredients concrete can be made hydrophobic( water resistant). In my line of work ,this is used in bridge decks

Hygroscopic

 

[Snobdds]

Snobdds
Your explanations are as clear as if they came from your avatar

I was at work, forgive me.

Just curious how hydrophobic concrete continues to cure in the absence of water after the initial cure.

 

[Streetcar]

I was at work, forgive me.

Just curious how hydrophobic concrete continues to cure in the absence of water after the initial cure.

The curing of the concrete is complete with the initial mix water. Concrete typically will have curing compound or kept damp to make sure the surface of the concrete does not dry out prior to concrete achieving proper strength

 

[SPYDERLK]

The documentary I saw years ago, I believe, said that the concrete might never cure had it not been for this cooling measure.

Documentaries are dumb. You see this when you listen to one on something you know a LOT about. In some cases the presenters are not really the experts and are parroting. In others it is just written for the level they expect of the audience. Lots of true statements can give the wrong idea, like happened with you - and Streetcar is giving great perspective on.

To elaborate some: Any reaction is accelerated by heat. An exothermic reaction is accelerated by the heat it produces. The faster it goes the faster it produces heat, etc. - A chain reaction.​

Even though concrete is a fairly slow reaction, when you have a huge quantity curing it is very difficult to keep the center portions of the curing mass from a thermal runaway. It is quite conceivable that it will boil its water and build high steam pressure. This could fracture the bonds forming in the curing concrete leaving it weak, or destroyed, depending on degree. And the water is gone. Whatever bonds remaining to be made during cure cannot form until water becomes available - and the bonds already broken are gone forever.

So you can see how the simple statement in the documentary, though correct can leave the listener with a picture so incomplete as to mislead.​

Industrial toys
The cooling measures allowed the concrete to be placed sooner adjacent previously placed concrete. Theoretically concrete will continue to gain strength as long as water is available for continued hydration. 99 percent of ultimate strength is reached within 56 days in most concrete