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`"rebar" = f( 3 , "r" ,pi, 18 , 1 , 4 , 40 , 60 )`

Enter a value for all fields

The **Rebar in a Circular Shaped Slab** calculator estimates the total **length** and **weight** of reinforcement bars (rebar) needed for a circular shaped concrete slab.

**INSTRUCTIONS:** Choose units and enter the following:

- (
**r**) Radius of Circular Slab (e.g. 12 ft). - (
**D**) Depth of Slab (e.g. 6") - (
**i**) Inset from the edge of the circular slab (e.g. 3 inches) - (
**oC**) on-center spacing of the rebar. - (
**rS**) Rebar Size - (
**LF**) Lapping Factor - (
**M**) Number of rebar mats - (
**rL**) un-cut Rebar Length - (
**WL**) Output choice: Choose rebar**weight**or**length** - Details Option

**Weight and Length of Rebar in a Circular Slab:** The calculator returns the length of rebar in feet, and the weight rebar in pounds. However, these can be automatically converted to compatible units via the pull-down menu. If details are chosen ("YES"), the calculator also returns the following:

- Surface Area of Slab in square feet
- Total Volume of the Slab in cubic yards
- Volume of Concrete in cubic yards
- Concrete Displaced by Rebar in cubic yards

However, these to can be automatically converted to compatible units (e.g. meters or kilograms) via the pull-down menu.

- Cubic Yards of Concrete in a Circular Slab
- Amount of rebar needed in a circular slab
- Surface area of a circular concrete slab
- Perimeter or circumference of a circular concrete slab
- Weight of Concrete in a Circular Slab

The rebar in a circular slab algorithm starts with the center lines (horizontal and vertical) and works outward.

Rebar is short for reinforcing bar. Rebar is a roughly circular steel bar with ribs used to provide added tensile strength to concrete structures. Rebar is put in place before concrete is poured. When the concrete has hardened, the concrete around the rebar ribs keep the rebar in place. Rebar and concrete expand similarly with temperature variations. This all has the net result of substantially added tensile strength when rebar is part of the concrete form. Carbon steel is the most commonly used material for rebar, which may also be coated with zinc or epoxy resin.

Rebar is laid out in grids, crisscrossed patterns of rebar, tied at the intersections where runs of rebar touch. The grids have spacing between the rebar rows, and they are placed within the concrete form by a specified inset from the edge of the concrete. Multiple parallel grids, at uniform space intervals, are referred to as rebar mats.

- Rebar - reinforcing steel bar.
- Stick - one length of rebar. In the U.S., the most common lengths of rebar sticks are 20', 40' and 60'.
- Lapping - when two sticks of rebar are overlapped and bound together.
- Lapping Factor - the multiple of a rebar diameter used to specify appropriate rebar lapping length.
- Mat - a crisscross grid of rebar sticks. There may be more than one mat with space in between mats.
- Size - the indicator of the diameter of rebar sticks. Note: guage is not a correct term for rebar.

In the United States, rebar sizes are in increments of 1/8^{th} inches in diameter. Therefore, size 4 is 4/8^{th} of an inch, which is 1/2", and size 8 is a full inch in diameter. Based on this and the density of steel used in rebar, the Rebar Size Table contains reasonably accurate specifications of rebar linear weight and lateral (face) area based on rebar size.

The most common lengths of pre-cut rebar in the United States are 20`, 40' and 60'. These are known as rebar sticks. When the dimensions of a slab, wall or other form exceed the length of a single stick of rebar, it is required to overlap and tie rebar pieces to create the added length. This process is called lapping, and the length of the overlapping rebar is the rebar lapping length. The length of the lap is specified by a "Lapping Factor (LF)" which is often 40 or 60 times the diameter of the rebar. Engineering specifications of a lapping factor should always be applied.

A class of rebar tools, both powered and manual, have been developed to aid construction workers in working with rebar. These include the following:

- Rebar Cutters are used to cleanly and safely cut sections of rebar.
- Rebar Benders are used to bend rebar sticks precisely to fit into concrete forms.
- Rebar Tiers are used to tie rebar grid intersections and for rebar lapping.

- Brick or Block Wall - Number of brick or block needed for a wall.
- Foundation - Poured - Amount of concrete needed for a poured foundation.
- Foundation - Block - Number of blocks needed for a foundation.