pour strips in in-situ slab on grade
pour strips in in-situ slab on grade
(OP)
hi everyone,
I'm working with a contractor on a G+4 level residential project with a basement. The basement parking is slab on grade with a raft slab thickness of 350mm. The area is around 160m X 65m with only construction joints and no expansion or control joints. The consultant is asking for pour strips even though it is cast insitu and not PT. Is there any specification in code books related to the requirement of pour strips? As contractors we strictly want to avoid this due to the delay in work. Are pour strips necessary in a building unit like this? Any code book reference would also be really helpful so we can hold our stand. Also would like to mention the construction site is a desert area in the middle east with high temperatures during summer.
I'm working with a contractor on a G+4 level residential project with a basement. The basement parking is slab on grade with a raft slab thickness of 350mm. The area is around 160m X 65m with only construction joints and no expansion or control joints. The consultant is asking for pour strips even though it is cast insitu and not PT. Is there any specification in code books related to the requirement of pour strips? As contractors we strictly want to avoid this due to the delay in work. Are pour strips necessary in a building unit like this? Any code book reference would also be really helpful so we can hold our stand. Also would like to mention the construction site is a desert area in the middle east with high temperatures during summer.






RE: pour strips in in-situ slab on grade
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RE: pour strips in in-situ slab on grade
There are ways to add reinforcement, post-tensioning, shrinkage reducing admixtures, etc. to minimize the number of joints, pour strips or staging.
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RE: pour strips in in-situ slab on grade
I also know of no code requirement for pour strips. But then, if designers limited themselves to only what the code specifically told them to do, we'd have lot of performance issues cropping up in our building stock.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: pour strips in in-situ slab on grade
RE: pour strips in in-situ slab on grade
1) The piles and caps are going to "hang up" slab movement in a way that columns in a suspended slab would not. This will reduce the effectiveness of the delay strips.
2) Unless delay strips are also cast into the basement walls, which is rare, the basement walls are also going to "hang up" slab movement. Depending on how fast you'll have the walls up, this may also limit delay strip effectiveness.
3) A suspended slab on grade will have 2-5X the reinforcement of a conventional slab on grade. This will help with shrinkage cracking.
4) Can you pour your concrete in transverse strips alternating from one side of the building then the other? This might gain you some of the benefits of of a delay strip without actually having one.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: pour strips in in-situ slab on grade
Thanks a lot. That was very helpful. Yes we argued that since this was resting on soil and not suspended above, shrinkage will be greatly reduced. We are using precast hollow core slabs for the ground floor level.
And they want continuous pour strips through the walls as well, another idea which we are not so thrilled about.
We have 5 pour sequences proposed with the first strip being divided into two for easier execution. I can talk to the project manager about your idea of alternate pouring. The gap between each pour is almost 7 days. If it is alright with the PM to execute on site then that would be greatly beneficial.
RE: pour strips in in-situ slab on grade
The verdict just came in. The municipality has asked for pour strips so we have to stick with that now. Both in slabs and continuing through the walls. Now I have to design and provide detailing for the strip areas. Could you please give me tips on how a pour strip is designed?(width, total number of strips required, location and how the reinforcement varies there). I searched online but all results on pour strip design are related to PT slabs and not RCC
RE: pour strips in in-situ slab on grade