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ari
Registered Users
Posts:4
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| 11/24/2001 5:54 PM |
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| what is the maximum wall height continuously poured using ICF wall? |
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Ian ICF Builders
Registered Users
Posts:612
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| 11/25/2001 9:56 AM |
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| That's a loaded question. You need to provide more information. Please describe the application. Is the wall backfilled? What concrete thickness? Is this wall straight with no corners?....Please describe the application. You ultimately should consult with a local structural engineer that is familiar with concrete structures. The fact that ICF is used shouldn't detract from the strengths of a generic concrete wall much especially if you planned on using a solid monolithic wall type ICF. |
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markross
Registered Users
Posts:1035
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| 11/25/2001 8:57 PM |
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Ari:
Using the form that you are using, I would not push it beyond 12'. We have done up to 26'in one day, but its more work than it is worth.
Mark Ross
"Le Canuck" |
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OKBlocker
Registered Users
Posts:635
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| 11/25/2001 10:49 PM |
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| 18' 10" |
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enermizermuskoka
Registered Users
Posts:272
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| 11/26/2001 5:36 PM |
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Very Grey area, when it comes to building code interpretation. Up here in North Ontario the maximum height "they" say is 12'9
for the allowable drop. However, in a municiple project I did- there was a blind eye cast over this issue, as I had to pour
16' uninterupted. I could have been regulated to the pour height restrictions, and would have had to cut "pour pockets" in various locations to allow the "legal" drop
or fall of the concrete.
In any event, check out what YOUR LOCAL
building official may require. After all is said, it is the inspectors interpretation of
that areas code which will dictate the direction you will go.
Hope this helps. Take-care, Sincerely.C.Kerr
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OKBlocker
Registered Users
Posts:635
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| 11/26/2001 7:11 PM |
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Chris,
Although we poured 18'10" in one day, we did not drop our concrete but about 9'
At 9' we cut 4" round holes in the wall at different horizontal spacing and pumped into these holes. Once the concrete was at that level, we plugged the holes with the styrofoam cut outs and went ahead and poured the rest of the house. That afternoon, while the pump truck was still there, we got on top of the 18'10" and topped it out also, all in one day.
As far as dropping your concrete certain distances, we are allowed to have a "trimmy" or flexibale shute (large rubber hose) and place it in the wall down to a certain level. This allows the concrete to reach the lower cavities without seperation.
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enermizermuskoka
Registered Users
Posts:272
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| 11/26/2001 8:01 PM |
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Thanks Tim, that's exactly the kind of thought I was trying to get out. Well put sir.- Long day it was. Take-care,Sincerely.C.Kerr
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jdcoombs
Registered Users
Posts:57
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| 11/28/2001 10:26 AM |
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Christopher,
Does that mean that our northern friends restrict the "legal" drop distance by code? Interesting if true.
Jerry D. Coombs, PE
American Polysteel, LLC
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Ian ICF Builders
Registered Users
Posts:612
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| 11/28/2001 11:31 AM |
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| A Corps of Engineers project we did had a height limitation of 10' with a 3/8" 6" slump....deviations were not permitted (that is greater height or slump) |
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Rick
Registered Users
Posts:157
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| 11/28/2001 11:36 AM |
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| JD-the answer is YES. In some places, allowing the concrete to drop more than 8-10 feet is a no-no. Thats a bit extreme, but some muncipalities stick by that. Only in Canada, eh? |
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markross
Registered Users
Posts:1035
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| 11/29/2001 11:48 PM |
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Concrete can actually be dropped quite a distance, however there is a lot of criteria which effects how far concrete should, and I repeat should be dropped according to conditions.
A good example is slump. The lower the slump, in effect the higher the drop can be, but who wants to place 2" slump concrete anyway. Also, the additives have an impact. Water reducers or retarders for example allow the coarse aggregate to move very freely within the mix, ergo allowing the heavy mass items, such as the stones to travel much deeper into the mass of concrete, not unlike the difference in firing a bullet into a stiff sand pile, or into mud. The resistance is less in the mud, or more fluid acting mass than the sand pile, therefor the equal mass of each bullet penetrates farther. Also, the ratio mix for portland/fine aggregate/coarse aggregate play a role in this in that more fines, with less coarse tends to separate far more easily than a mix with higher percentages of course aggregate. In essence, we have decreased movement and spread the kinetic energy to a greater number of equal mass items, therefor distributing the energy of the impacting coarse or heavy mass aggregate, over a broader area. In essence, we have increased the pressure cone of impact from a small diameter, to spread the load over a larger diameter area. Ah...I mean its like the difference in walking in deep snow with just boots, and walkning in the same snow with snowshoes.... Maybe. This is a tough one to explain.
As well, if you place the concrete by dropping it on the ties, in theory, you may think you are slowing the concrete down and doin a "good thing"... But are you. Ideally all concrete should be places as a mass, and breaking up that mass by impacting the ties, often causes a significant amount of segregation, leaving the coarse aggregate or stone to crash down to the bottom of the wall prior to the fines and portland, which are too small and light to keep up, as they tumble and bounce around the interior of the formwork.
I believe that I lost myself in this here, and what I ment to say is... the height of the drop is a direct relation to site placement, concrete mix designs and placement techniqes, which are unique to each job, form type, weather condition and crew. Hench this is where expierience counts, a good installer knows what to look for at each job, and access's the entire project on a one at a time basis, recognizing the need for change as conditions change.
We have done up to 26' with drops of up to 21' no seggregation problems or blow outs for 2-1/2 years.
Mark Ross
"Le Canuck" |
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jdcoombs
Registered Users
Posts:57
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| 11/30/2001 1:14 PM |
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Wow, a lot of info here. I've heard most of this stuff before, but fact is, "it ain't so." For placeable concrete, that is, anything that isn't soup, all available studies have shown that there is NO CORRELATION between height of free fall and segregation or any other negative result in the concrete. Unless, of course it's falling so far that it dries out before it hits. Even concrete striking form sides and ties helps to keep concrete well mixed. Everything is merely left to consolidation. The corps of Engineers is the only official organization that made a broad assumption long ago on what they thought happens, but didn't study it; and now they still have this limited drop requiremnt. The limitation is often still introduced into commercial projects by the engineer's specs all based on the CoE stand. In addition, local juristictions often arbitrarily place a limit. But there is no official document or code restriction (that I know of) in the US that limits concrete free-fall based on segregation. Was wondering if there's one in Canada and what references it has. Any info? I have a really good article in one of my piles around here that I could reference for those interested if I ever run across it again.
Jerry D. Coombs
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markross
Registered Users
Posts:1035
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| 11/30/2001 8:32 PM |
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Jerry:
Yeah, theres a restriction in canada, yep and a report, although I know not what it is called, I believe the CPCA (or the new CAC) would have a study for you. Have fun.
But what you say makes sense, although most dont consolodate, which will, in essence, re-mix the lower portions. I have just seen too many ICF homes built on a gravel base.
Mark Ross
"Le Canuck" |
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