So we have a ice and some snow, at the bottom of our ICF wall forms. The ice is in our keyway, which is the size of a 2x4. We didn't have the foresight to put in any weep holes when we poured our footer - oops. Now I need a way to melt all of this ice before we pour on Thursday. I tried a little propane tube heater, piping the heat into the forms but, it blows too hot, and melts the foam. I threw some handfuls of rock salt down there but I think I would need quite a lot of it. I have no idea if this would negatively affect the concrete or not...? Plus, and maybe someone can clarify this, if I melt the ice with a ton of salt (or ice melt - which is better?), will the salt stay in solution with the water and keep it from re-freezing? Starting Tuesday the lowest temp I will see is 25F. I will dump hundreds of pounds of salt down my walls if thats what it takes, as long as I am sure the ice will melt and not refreeze. Once I melt it I think I can shop vac it out, or just leave it in place and let it mix with my concrete - thats not a issue. My issue is removing the ice. OR - What other options do I have?

I used a small electric(1KW) heater to warm up the blocks as the holes in the interlocking teeth were filled with ice and frost when we assembled our wall. It was small enough to fit down into the space between the crossties. With the top of the forms covered, the heater will recirc and heat the air inside, and eventualy get the air inside above freezing(it is afterall well insulated). This is easier if you have openings in the wall and can get the heater in down near the bottom so it is adding heat to the coolest air. This of course needs to overcome the conduction losses thru the footing.

Another issue I had was that my foam glue didn't take the first time(footing too damp) when I glued the blocks down. I had to get the footing thawed and dry to re-foam the blocks to the footing. I put black poly over the whole wall down over the footings(made kind of a long tent). I used a weed burner and a fan to heat the whole tent. This thawed and dried the footing allowing me to re-establish my straight line and foam the blocks to the footing... Might be you can combine these two with your propane tube heater heating the tent and one side of the footing and melt out the keyway.

I would not put salt down there, I would figure a way to melt it and vacume the water out...

Good Luck.

Rock salt and concrete are not a good mix. Creates a bad chemical reaction, especially with rebar.

I forgot to mention that I did put down a water proofing agent as a capillary break on the footer, so in theory, no salt water should get into the concrete at all. Then if I shop cav it out, maybe I wont have a problem at all??

It is a cement based product though(tamoseal)

What about ice melt ie Calcium Chloride? The add that as an accelerator to concrete.
For reinforced concrete that is dry or protected from
moisture in service, ACI 318 permits a maximum
water-soluble chloride ion (CI–) content in concrete,
of 1% percent by weight of cement.

https://www.ascconline.org/Portals/0/docs/POSITION-STATEMENTS/PS-31-acceptable-use-calcium-chloride-concrete.pdf

Can you adjust your propane heater (more air, less propane) such that the output is less than 200F? Or cover everything with insulation such that ground heat will melt the ice?

Well I'm going to try to turn the heat Down on the heater by limiting it at the propane tank. The heater itself was melting it at its lowest setting

I'd wait until air temp was at or above freezing, then use a garden hose to flush out the snow/ice (and rock salt).

Shop vac the extra water out of the keyway if it will get below freezing again before your pour.

Usually when pumping an icf you wouldn't want the set to be accelerated.

Posted By nd96 on 19 Dec 2016 03:17 AM
I'd wait until air temp was at or above freezing, then use a garden hose to flush out the snow/ice (and rock salt).

Shop vac the extra water out of the keyway if it will get below freezing again before your pour.

I would do that but I dont have access to water yet.

If Thursday's pour is critical, rent a water truck and have it come with warm water. It takes a LOT of energy to melt snow and ice, but if you can flush most of it out, you won't be relying on melting. Vacuum up what's left and cover the top with plastic to keep more water out. Warm water will give you time to get the vacuuming done before the cold concrete refreezes anything.

Well it went off without a hitch. We ended up using calcium chloride ice melt which worked great and didnt take very much at all. Melted everything a day or two in advance adding as little product as possible over those two days.

Pouring is a lot more difficult that it looks in the videos! But went off without a hitch. I used the Amvic Plus block and they proved to be quite stout. In one area I filled it to an 8 foot lift without even knowing it and the wall didnt budge. I suspect I could have done the whole wall in one lift if I wanted to.

Great news!