What reinforcement to 150mm slab on No Fines Concrete
What reinforcement to 150mm slab on No Fines Concrete
(OP)
I am designing a slab to a water treatment works reactor where the slab is to rest on a layer of no fines concrete that acts as a drain should any effluent get through the slab. The design from our water department is for 12m long slab sections. The slab is 150mm thick. I know that the no fines will bond to the slab cast over it and will resist almost all movement. This will reslut in cracking. Now to limit my crack widths to say 0.2-0.3mm, what rebar would you consider sufficient?
I am using BS8007, liquid retaining structures, and get Y10's @ 200mm centres. But would it be prudent to have even more rebar seeing that the slab is cast onto a substrate with which it will form a very strong bond and resist any shrinkage movement at the bottom?
I am using BS8007, liquid retaining structures, and get Y10's @ 200mm centres. But would it be prudent to have even more rebar seeing that the slab is cast onto a substrate with which it will form a very strong bond and resist any shrinkage movement at the bottom?






RE: What reinforcement to 150mm slab on No Fines Concrete
RE: What reinforcement to 150mm slab on No Fines Concrete
With joints that far apart, you may as well leave them out. The joints won't prevent any of the cracking which will occur.
Is the effluent corrosive? If so, I would use galvanized bars.
RE: What reinforcement to 150mm slab on No Fines Concrete
If you sawcut the control joints properly and provide proper spacing, you can then seal the joints with a semi-rigid epoxy and achieve good performance.
RE: What reinforcement to 150mm slab on No Fines Concrete
If this is not a slab subject to traffic, and you adopt Ron's jointed approach, I would use a flexible polyurethane sealant rather than the semi-rigid epoxy.
RE: What reinforcement to 150mm slab on No Fines Concrete