monolithic conrete slab cross section

by johnson ford
(spain)

Question:

12 by 13 feet of slab, i want to know the main bars and transversal bar?

Answer:
Hi Johnson, thanks for visiting all-concrete-cement.com

The fact that you want a monolithic slab for such a small concrete slab 12'x13' tells me that the slab is intended to support a structure of some type.

The sketch below shows a monolithic concrete slab cross section. The two thickened edges at the corner of the cross section is the reason why this slab diagram is a monolithic slab.

It is monolithic because the slab and footings or thickened edge are poured simultaneously thus the term monolithic.

The reinforcements at the middle of the slab below is exactly the same as that of a regular slab without the thicken slab.



Thickened edge slab is also known as turn down slab that require the reinforcements to follow the shape of the edges of the slab. That's why you see the hook shape of the rebar in the diagram.

Sometimes the thickened edge can go down as deep as 4 feet or deeper. In such instance the reinforcements will look like that of foundation walls.

Not shown in the diagram are the bottom reinforcements at the bottom of the thicken edge footing. Depending on engineer preference, such footing reinforcements can either be a single rebar or double rebars all around the perimeter.

As far as the size of the rebar,#3 bars or 3/8 inch diameter bars should be more than what is needed. If the slab is to support very heavy equipment than use #4 bars spaced at 12 inches on center for both the longitudinal and transverse bars.

If you cut another sectional of the slab perpendicular to what is shown above you should have the exact same detail only with a 13ft dimension. In other words all four sides of the slab reinforcements should be the same.

Hope this helps
Good luck
Tonga