Expanded Metal Mesh - Joint Former

[mcutchi]

Does anyone have experience of using expamet as a construction joint former for thick pours ? I have a 5 ft thick slab (20ft x 88 ft). The contractor wants to break up the pour using expamet rather than regular formwork, presumably so he can get his shear dowels through easily. I always thought this a bad idea since use of a vibrator near the joint would result in grout loss through the mesh. Any experiences ?

 

[boffintech]

I was on a job just last week where the contractor attempted to place a vertical construction joint in a 32" wide 20' tall shearwall using this material. The concrete placement was going great up to about 12' and then .... huge blowout when the mesh broke away from the form. Geeezzzz what a mess, but it wasn't anything 20 guys with shovels and a fire hose couldn't clean up.

 

[DTGT2002]

I have designed a bulkhead out of StayForm for a 30 deep SOG that performed well. There was grout loss at the mesh and the vibrator must be kept 1-2' from the mesh face. The mesh was backed with rebar dowels and the top of the dowels were held back with #9 wire secured within the slab area to be poured.

Stayform is a brand name our supervision was familiar with and I have used it for various blind sided retaining walls in the past.

With proper engineering, a bulkhead like this can work. I 'd think for your height, the design would be much like a typical stick built form, but with the mesh in place of plyform.

Good Luck!

Daniel Toon