Control Joints in S.O.G.

[Ryan H]

I have a 24.5' x 64' section of slab on grade (10") that I have joints: 1 vertical and 1 hor. cutting the slab into 4 sections each 12.5 x 32 roughly. the architect has floor drains in the middle of the 24.5x64 section and the slab sloping to the drains. they want joints coming from each corner on the diagonal to the opposite corner. these would be in addition to the ones I already have. now the slab is a bunch of triangles.

my questions are?
1. is there concern for the size of the slab points where they call meet at the drain. it's a drain with 8 joints coming in to it. one top and bottom. one left and right. and one at each diagonal
2. it is a drain so i thought about using a diamond control joint pattern, similar to the base of a column, to move the joints away slightly.
3. since the slab is sloping to the middle, I really don't think I can cut this up any other way?

 

[jayrod12]

Why does it need to be cut in triangles due to the slope? They're going to have the slab slope done before the cuts are made.

I personally would not be going to the triangles, I also am of the opinion that 32 feet is too long in the one direction. So I'd actually be cutting the slab up into 12.5x16 rectangles. The closer you can get to square pieces, the lower the chances of random shrinkage cracking.

 

[KootK]

True, diagonal contraction joints don't make much sense for the reasons that both you and jayrod mentioned. Are you sure that somebody hasn't mistaken the pitch lines that define the slope of the slab for contraction joints? those are normally two different things.

 

[dik]

You don't want to cut it into triangle... cracking can occur at the points (aka verticies) of the triangles. Make sure you sawcut it at the right time (critical).

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[PEinc]

Joint quantity and location(s) could depend on the number and locations of the floor drains which are currently undefined. Why not three slab sections at 221.33' x 24.5'? almost square and not too big.

http://www.PeirceEngineering.com

 

[PEinc]

Sorry. I had a fat finger typo in my previous response. I meant to type 21.33' x 24.5' (not 221.33' x 24.5').

http://www.PeirceEngineering.com