Reforcement requirements for topping slabs?

[StructureMan44]

We're locating equipment on top of an existing slab. The existing floor slab is 6'4" thick with an 8" non-sloping topping slab on top. The new equipment has the potential to spill and we believe it will be more economical to add another 6" topping slab (sloped) on top of the existing topping slab and cut drainage trenches in the existing topping slab. What is the minimum required reinforcement for this new topping slab? ACI 318 has minimums in section 7.12 but this slab won't be structural.

 

[SlideRuleEra]

A fully bonded overlay does not need reinforcement. A partially bonded or unbonded overlay does. Since the new 6" overlay will be sloped and the underlying concrete is level, I assume thickness will vary from 6" to a smaller value. Reinforcing concrete less than 6" thick is tricky. Probably best to go with a fully bonded overlay and no reinforcement.

See the Portland Cement Association paper Resurfacing Concrete Foors

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[MotorCity]

Whether the topping is bonded or unbounded, it has the potential to crack. This could occur as a result of movement in the base slab or perhaps an impact force on the topping slab. If you are concerned about the integrity of the topping with regard to spills, I would add reinforcement to minimize the potential crack width. For slab toppings with reinforcement, we usually use steel fibers (industrial projects)

 

[StructureMan44]

SlideRuleEra: Thank you for your response and great attachment

MotorCity: This is an industrial project. Are the steel fibers you use a specific WWR?

 

[BAretired]

Will the drainage trenches cut into the existing topping be lined with waterproof material?

BA

 

[MotorCity]

We use steel fibers or WWF, not both. Using both in a thin topping would make it nearly impossible to place and finish the concrete properly.