I'm new to the forums and new to ICF construction. I'm building a 20x20 shop with a full basement using ICFs. Its a small project I was hoping to do mostly by myself with some volunteer help and with the use of a 1/4 yard cement mixer. I'm wondering if its possible to do a multi-stage pour over the course of a few days and if the resulting cold joints would be a structural/waterproofing concern. Ideally i'd like to do the pour in 5 stages, one for the footing and then the wall in 2.5' sections. I intend to rough up the top surface of each level and possibly may use a concrete adhesive if necessary. Is this the right way to go about it or am I just creating more potential for problems then if I was to do a two stage pour?

If my math is right, the 20'x20' floor at 4" thick is almost 5 yards of concrete.

One level of 20'x20'x8' high wall that is 6" thick is almost 17 yards of concrete.

That doesn't count the footing which depending on your soil conditions could be 2' wide and a foot thick for another 6 yards of concrete.

It looks like you'll be doing a lot of mixing to mix 23 yards with a 1/4 yard mixer and that is only one 6" level. If 8" blocks are used, the quantity will be more. Of course the amount will double if you are going two stories high. If you aren't in really good shape now, you will be when you're done mixing and moving all that concrete.

If it were me, I'd just order the ready mix truck to deliver the concrete. Your mix quality will be much better and you'll get the job done with less pain.

You might consider no basement or footings by using a frost protected shallow foundation. Then SCIPs for the walls (much less concrete). Small sprayers are available:

http://www.mortarsprayer.com/stucco-sprayer-wall-ceiling-combo/

If you are dead set on stairs you could add a loft. If you don't like SCIPs, then maybe dry stacked CMU.

That's about right for the ratios, I had anticipated using about 25 yards depending on the wall thickness. The extra work of mixing it myself doesn't bother me, once you get into a groove it goes by pretty quickly. Plus I was hoping I can spread it out over a week or two by only pouring 5 yards at a time but that would mean i'm not pouring all of the walls at once. My main concern as I mentioned is whether the multiple cold joints in the wall will have any effect on structural integrity

You can add bonding agents and more steel to help with this, but I don't know the figures. Even better, use threaded rods top to bottom (post tensioning - cold joints are fine in compression and the rods convert tension to compression). As an example, could reduce requirements from an 8" thick wall down to 6".

In my experience, engineers do not like have cold joints in below grade walls. Even if this is not an engineered project, I would reconsider using the mixer, as you will end up with countless cold joints throughout the walls and slabs, which may change your structure.

On the other hand, there are a lot of old buildings and foundations in ghost towns and old farms around the country, especially Idaho, that are still in good condition. They were poured upwards of a hundred years ago before ready mix existed and hand labor was the norm!

Lots of cold joints in this construction project!!

Hoover's Heat of hydration

To counteract the problem of heat generation, Hoover dam was built in series of inter locking blocks. This idea was conceived by a previous dam called Lower Crystal Spring dams. But Hoover was even 20 times massive than gigantic Lower Crystals Spring Dam. Each block was 5 ft high and was inter locked with the neighboring one and water was forced between them. To accelerate the setting of concrete, cool water pipes were passed through each block. Concrete mix was cooled and cured faster.

Cooling it down "accelerated the setting of the concrete"? I think something got garbled there. But there is a point - build a concrete wall during cold weather and you could get the next layer in before it sets - even if you took the evening and night off. Or add set retarder to get the same effect.

In everyday concrete placements like walls and slabs cooling is not an issue, so we never see the effects that heat retention may cause. In massive placements like Hoover Dam and Grand Coulee Dam the concrete would stay hot for decades upon decades without cooling pipes being added. Apparently that long term heat retention has a serious impact on the curing process, or why would they add cooling tubes?

When I visited Grand Coulee in about 1967 the tour guide said the cooling pipes had been taken out of service only a few years before, roughly 30 years after construction began.

They mean "accelerated the entire process of building the dam", "prevented damaging overheating" or something like that. Cooling slows setting.

Posted By jonr on 28 Jun 2011 07:05 PM
They mean "accelerated the entire process of building the dam", "prevented damaging overheating" or something like that. Cooling slows setting.

Makes sense. From a quick search I find that the real problem caused by the heat of curing is cracking from thermal stresses from temp differences from the interior to exterior. From my limited knowledge of concrete I understand curing actually continues for years so heat will be generated for years. If it weren't removed at a rate commensurate with its rate of generation the interior would heat up. Obviously this happens because the rate of heat transfer within the concrete is less than the rate of heat generation.

Here's another interesting comment I came across regarding temperature of concrete. It's at http://www.ce.memphis.edu/1101/notes/concrete/everything_about_concrete/10_curing.html.

"Effect of Temperature -- Increased temperature results in improved early strength and lower ultimate strength. The early strength gain is explained by the increase of the hydration process. The lower ultimate strength is more difficult to explain, but seems to be related to non-uniform development of the microstructure."

So, the conclusion is you want concrete to be not too cool, nor too hot, while it is curing.

I would say cooler is better unless you are talking about below freezing or have some special need for speed (like having to strip and return forms). And definitely don't let it dry early - use plastic or sprinklers or curing agent to prevent that.

It's easy to make 2000 psi concrete - or 6000 psi concrete. Makes a big difference as to how much of it you need (at least strength wise).

right on, i'm planning to pour this fall anyways, so maybe i'll push it back to late fall to utilize the cooler temperatures. Oh and one of the reasons I plan on using the 1/4 yard mixer was because the shop location in my back yard is inaccessible to vehicles. It took myself and 2 others about 4 hours to mix and pour 9 yards for a concrete patio recently, we mixed in the driveway and the wheel barrow had to travel about 50 yards round trip. I did most of the sack lifting myself, everyone elses jobs were pretty easy in comparison. I figure for this project about 2 hours to mix 5 yards with the wheel barrow traveling shorter distances. It seems like alot more work but free labor + materials is alot cheaper then a cement truck. Does anyone have an ICF block supplier in the northwest theyd recommend? I've heard boise cascade can supply you but i'm sure they are only an intermediate dealer to the real supplier.

Posted By idahogreen on 28 Jun 2011 10:45 PM
... Does anyone have an ICF block supplier in the northwest theyd recommend?

I'm not sure if LiteForm supplies to that area or not, but it would be worthwhile to check with them.  You can do an online material estimate here:

http://www.liteform.com/Lite_Form/estimate.php

Mike Morrison covers that area, 541.261.3606