Clarifier Grout Topping Construction Joints

[kcbusse]

thread592-122542

Referencing above thread from 2005. Looking for any input regarding the placement of a 2" topping being finish with clarifier equipment/screed. We are looking to pour in 3 concentric circles, pouring the inner and outer circles on the same day and the middle circle on a second pour day. Any advice on installing a radial bulkhead that would clear the clarifier raker arm? Any input on how othera have poured would be appreciated.

Thanks

 

[JedClampett]

I think you're overcomplicating this. Unless there is a supply problem or this is so huge that it can't be physically done in a day, I'd not put in any construction joints and knock it out in one day. If it's a supply issue, I'd skip bulkheads and just trim the edge as vertical as possible. You'd like a rough surface so the next pour can bite into the older one. But these are basically leveling pours and you will get some small cracks.
The reasons for putting in construction joints don't really apply here. Trying to organize your cracks in a clarifier bottom to make them prettier is not important. It's under 14 or 15 feet of water for pity's sake.

 

[kcbusse]

Clarifiers are 160' in diameter so client/engineer will not approve a single pour. They base slabs were poured in 8 pies (per contract drawing construction joints) and they initially wanted the topping joints to mimic the slab joints. We would love to pour in a single shot but they argue the construction joints they want to impose is to control the cracking.

 

[JedClampett]

OK. I don't see any harm in it. Maybe you can put some 2 x's in there sideways with a little piece of plywood to bulkhead, or split the lumber to make them exactly 2 inches.