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Calcium Chloride in Concrete

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No, Fountain, you haven't fallen from the train.

Calcium chloride is an accelerant and is used in very cold climates to have 
the concrete set up quickly.  I don't believe that you would have a need for 
it in Florida just as we don't have a need for it in southern Arizona.  There 
are enough accelerating admixtures available that are calcium chloride free 
so that there is little need to use calcium chloride.

Calcium chloride is doubly bad if there is any aluminum embedded in the 
concrete, such as aluminum electric conduit.  (Aluminum and concrete is bad 
enough without adding calcium chloride to it!)  A proprietary liquid 
admixture promoted as providing water proof concrete has calcium chloride as 
its primary active ingredient and caused serious damage to an underground 
parking garage in Phoenix a number of years ago.  This product is also used 
by masons to accelerate the setting of mortar.

Stick by your guns, Fountain, and keep calcium chloride out of the concrete.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Fountain Conner wrote,

. > Have I fallen from the train?
. > 
. > I have never allowed Calcium Chloride in any of my concrete.
. > 
. > But contractors and concrete suppliers in this area (we sometimes have 
. > some low temperatures), will use it without even asking.
. > 
. > Has concrete chemistry changed so that calcium chloride is no longer
. > harmful to concrete and/or rebar?
. > 
. > 
. > Fountain E. Conner, P.E.
. > Gulf Breeze, Fl. 32561
. >