Long slab

[ydolotov]

Hi,
I have to pure slab 30'x200' 8".
How do it in one pass without expenthion join?
Thenks, Yevgen

 

[jheidt2543]

It depends a little on what the use of the slab will be. Is it a warehouse slab with "standard" tolerances? Is it a "superflat floor"? Is it a highway? Is it in a parking lot? What kind of a finish is it to have? Do you have the equipment and manpower to pour the slab in one continous pour? Will it be exposed to the elements while you are pouring it or is it under roof?

I think we need a little more information to give you an answer.

 

[ydolotov]

It will be "superflat floor" in the eight-store appartment building. But ground floor will be have two drop-steps, one feet each. Concrete 6000 psi. I gouing to use two concrete pumps.
In the one day I am going to pure column and other day slab.
How better doing there?
Thanks. Yevgen

 

[jheidt2543]

ydolotov,

I can't see why you need a superflat floor in an appartment building, do we have a problem in our use of terms? Virtually all the superflat floors I've seen have been used in warehouses.

However, based on the superflat floors I've seen, they are generally poured 12' - 15' wide by the full length of the building 200' - 500' long. It takes a pretty large crew to install a superflat floor, because the floor is struck off twice and then bullfloated twice - once in each direction. That is the reason for the narrow pour width, so the crews can reach across the pour with long handles on their bullfloats.

I'm sure you can get informatin on the web regarding superflat floor installation. In addition to superflat, look under "Face" and "Flatness" and "profilograph".

Once the floor is poured and finished cut the control joints ASAP. The best system, if it is available, is to use the "SoftCut" saw. You can cut the joints right after you are done troweling the slab.

Wet cure the floor 3-7 days then apply a cure & seal agent. If you are working in an enclosed area, then you can use a waterbased cure & seal so that you don't have to deal with the odor and air quality problems.

Hope this is some help.

 

[ydolotov]

Thanks a lot.
And what about monolitic flat slab 200'x(20'-40')x8" (not SUPERflat), which is opened from each side and is standing on columns. Gaps between columns near 20'. Where better start puring: from the center to the edges, from one edge to another, or from opposit edges to center, if I can use two pump. And what critical moments might occure during this time?
Thanks.
Yevgen

 

[jheidt2543]

In general, the pouring of a structural floor slab is the most dangerous time frame it will see. You can have very high unbalanced forces from the wet concrete and the construction equipment and people used to pour it. I assume you have a shoring system for the slab formwork, inspect it prior to the structural slab pour to MAKE SURE the shores have a good base bearing and the cross bracing system is installed correctly.

I would also submit your pouring sequence to the Engineer-of-Record for review and approval. He is the person most familiar with the structural requirements and design of the building so, he should be given the opportunity to review your pouring plan. He can tell if there are any areas of special concern during the pouring operations. He won't take responsibility for the shoring or the construction work, it isn't his job to do so, but he should review your proposed pouring sequence to see that it is not in conflict with his design assumptions.

 

[ydolotov]

Thanks.
Yes, we are doing shoring and bracing. We did not do slab longer 100' before and I am interesting in specific moments to do that slab monolitic.
Yevgen

 

[DTGT2002]

As a rule, I would surely begin pouring any pour from the center of the building. Even properly designed and installed crossbracing at the perimeter of the building cannot always keep the perimeter shoring in the building and prevent overturning at the perimeter. Often times, stability of the system is neglected, which in turns leads to overstress, or worse.

Your shoring system, whether wood, metal or otherwise must be able to handle all loads you could expect to place on it. If you are not confident in the design, you need to find a local Formwork/Falsework/Shoring Contractor and have their engineers review the system, or design an appropriate system.

Earlier, when you said expansion joint, did you mean construction joint, or pour break?

Good luck, and keep posting.

Daniel Toon