Plywood for concrete forms

[Snobdds]

Curing: How exactly does it work? << Concrete Countertop Institute

I guess there are using the fancy term of hydrating for water...which we all know concrete has in it.

 

[Snobdds]

I guess there are using the fancy term of hydrating for water...which we all know concrete has in it.

Hydrating is to always put water into something. Concrete "hydrates" once at the initial stage, then there is no more hydrating.

 

[/pine]

Forms are generally removed so they can be reused...the plywood is usually coated with an oil or release agent...

As an example of moisture permeating wood in direct contact with poured concrete...just look at the bearing surfaces of fabricated roof trusses...there will always be a "tin tab" at the bearing points to separate the wood from the conc. even thought the top of the poured beam (lintel) is protected from the elements...

IMO it will take years for moisture to exit through the plywood if left in contact with the pour...a moisture barrier (plastic/rubber sheeting etc.) may be a viable solution...

 

[Rock knocker]

No, it's a chemical reaction between the Portland and the lime. Water just keeps the chemical reaction, Cure, to a slower rate. There is no such thing as hydrating in concrete...

Here is one of the chemical formulas of the hydration of cement during the creation of concrete. You'll see that the water becomes part of the molecular structure of the polymer

2 Ca2SiO4 + 5 H2O---> 3 CaO.2SiO2.4H2O + Ca(OH)2 + 58.6 kJ
Concrete: Scientific Principles


In short, you just need to be quite, cause you don't seem to understand chemistry

 

[ovrszd]

Careful Rock knocker, you have mixed apples with your oranges and may get called out for it.

 

[Snobdds]

Here is one of the chemical formulas of the hydration of cement during the creation of concrete. You'll see that the water becomes part of the molecular structure of the polymer

2 Ca2SiO4 + 5 H2O---> 3 CaO.2SiO2.4H2O + Ca(OH)2 + 58.6 kJ
Concrete: Scientific Principles


In short, you just need to be quite, cause you don't seem to understand chemistry

So yea...portland, lime and water.

What point here are you making?

 

[Rock knocker]

Careful Rock knocker, you have mixed apples with your oranges and may get called out for it.

Explain.

 

[ovrszd]

Explain.

You were the first person to use the word "cement". The nitpickers on this thread may point that out to you in a negative way!!!

 

[Rock knocker]

So yea...portland, lime and water.

What point here are you making?

That the product is CaO.2SiO2.4H2O, which is a hydrous material

 

[mapper]

I remember a wall my dad and I built about fifty years ago, formed with plywood and lots of 2x4 bracing and steel tie rods, we thought. Well the whole thing held together but the plywood bulged out between the bracing so much that when the calculated volume of cement was poured the wall was about 2 feet shorter than planned.
I have noticed that the plywood that the concrete contractors around here use is at least 3/4", and appears to be faced with some sort of hard smooth laminate. It also looks to be void free with a lot more plys than ordinary lumber yard fare. In other words a lot more substantial than what my dad and I were using.