Calcium Chloride accelerator

[JAE]

Typically we do not allow calcium chlorides in concrete as an accelerator - but on a recent project I was asked if they could use it (vs. a "non-corrosive" accelerator) since the slab was not reinforced with ferrous materials - used synthetic fibers.

I thought that there were other adverse effects on concrete beyond causing wire mesh or rebar to rust but I'm not sure I can recall.

Any thoughts on the use of calcium chlorides in concrete?

 

[msquared48]

http://www.concreteconstruction.net/concrete-articles/calcium-chloride-in-flatwork.aspx

Increases shrinkage and can cause discoloration.

Hmmm. I think I just found the answer to my expert witness case if he ever signs the dotted line.

Thanks JAE...

Mike McCann
MMC Engineering

 

[TXStructural]

What about anchorages, embeds, steel studs in contact, etc.? Every slab has some steel accessories which could be subject to accelerated corrosion due to chloride exposure.

 

[Ron]

Yup...what TX said!

 

[JAE]

That's what I thought. I mentioned to the contractor that we still needed to shoot in the interior stud walls and that would be problematic with chlorides in there.

 

[TXStructural]

Why would anyone use chloride accelerators with the non-chloride options?

 

[JAE]

He indicated that the chloride option was $3/cu. yd. while the non-chloride option was $9/cu.yd.

 

[dik]

I only ever permit CaCl2 for temporary structures...

Dik

 

[msquared48]

JAE:

Wish we could get concrete that cheap here, even with the CC!

Mike McCann
MMC Engineering

 

[hokie66]

Why are calcium chloride accelerators still available? Having them in the plant means they may be used inappropriately...also, the synthetic fibres are just a marketing ploy.

 

[dik]

Hokie... because they're cheap and they work well and have a long history of application.

They also have a few problems, too...