Calcium Chloride in concrete for perimeter foundation??
Calcium Chloride in concrete for perimeter foundation??
(OP)
Hi,
I hired a contractor to replace the brick foundation on my two story house with an inverted "T" concrete foundation. The footing is 18" wide by 18" deep with an 8" stem wall. Reinforcing is #4 bars with 3" cover.
Only after the concrete was in the forms did he explain he had ordered the concrete with 2% CaCl2 in order to save some time. But I have read that CaCl2 should never be used with reinforced concrete because it will lead to rapid corrosion of rebars, with corrosion failures occurring as quickly as 10 years.
What is the typical experience with CaCl2, when there are no other sources of chlorides (The house is in San Francisco well above the groundwater so there are no salts from winter ice control or ground water table to contribute to the problem).
Is there any chance this foundation will survive for 50 or more years? Is there any mitigation, such as sealing the surface to minimize availability of oxygen, that is practical at this point?
thanks for any info you can provide
I hired a contractor to replace the brick foundation on my two story house with an inverted "T" concrete foundation. The footing is 18" wide by 18" deep with an 8" stem wall. Reinforcing is #4 bars with 3" cover.
Only after the concrete was in the forms did he explain he had ordered the concrete with 2% CaCl2 in order to save some time. But I have read that CaCl2 should never be used with reinforced concrete because it will lead to rapid corrosion of rebars, with corrosion failures occurring as quickly as 10 years.
What is the typical experience with CaCl2, when there are no other sources of chlorides (The house is in San Francisco well above the groundwater so there are no salts from winter ice control or ground water table to contribute to the problem).
Is there any chance this foundation will survive for 50 or more years? Is there any mitigation, such as sealing the surface to minimize availability of oxygen, that is practical at this point?
thanks for any info you can provide






RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
However, if the contractor did the permit drawings for you, those notes are probably not there!
I'm not sure of any mitigating action you can take, as I've never been involved in this sort of thing before...but you definitely need to do something.
Good luck.
RE: Calcium Chloride in concrete for perimeter foundation??
Have the contractor remove the concrete and start over. Not acceptable.
RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
The contractor said calcium chloride but I just got a look at the concrete delivery tag and it says:
"6 sack 1/2" PM PL NC 2 dosage"
Any chance the "NC 2 dosage" refers to a non-chloride accelerator of some sort? I plan to call the concrete plant tomorrow to ask them exactly what they mixed.
RE: Calcium Chloride in concrete for perimeter foundation??
Follow up. Be sure to check with that specific batch plant - a different one may use a different term.
Lots of dollars/lawyers involved here to recover the damages damages and rebuild - or to have the contractor to pay for the ripout, disposal, and replacement. Make a copy of the batch tag, use it. Don't lose the original.
RE: Calcium Chloride in concrete for perimeter foundation??
If chlorides show up anywhere, have them remove the concrete. If it clearly is a non-chloride accelerator, just inspect the concrete for any indication of problems from the faster set (most common will be plastic shrinkage cracks that do not heal and interconnect to become long cracks).
RE: Calcium Chloride in concrete for perimeter foundation??
The contractor said calcium chloride several times so that must be what he asked for. Fortunately the ready mix plant didnt fill his order exactly as he specified.
Thanks everyone for your feedback.
RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
I have used core drilling and taking slices for chloride testing before and it is great for determining chloride levels at various horizons/depths, which is very valuable for determining whether the chlorides have penetrated to the level of the reinforcement. However, if calcium chloride has been added to the mix, it should be more or less evenly distributed throughout the concrete. Therefore would it not be cheaper and less intrusive in this case to use a concrete drill bit, rather than core drilling, and collect a powdered sample directly from the drill hole? I have encountered labs in the Ontario area using this procedure before.
RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
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RE: Calcium Chloride in concrete for perimeter foundation??
RE: Calcium Chloride in concrete for perimeter foundation??
I have worked on upwards of twenty multistorey projects over the years (and have knowledge of many more) where concrete repairs were required on vertical, exterior elements and balcony slabs located above grade (i.e. away from deicing salts). Exposed slab edges, columns, shear walls and balcony slabs all showed signs of concrete delamination due to corrosion of the rebar. Testing, in the majority of cases showed elevated chlorides. However, I will add that the majority of problems occurred at locations where there were chlorides AND low concrete cover. Where concrete cover was significant, there were much fewer problems.