The Weight of Rebar in a Slab calculator computes the total weight Concrete Slab with one Rebar Grid mat of reinforcement bars (rebar) needed for a concrete slab based on the dimensions of the slab and the spacing and size of the rebar.
INSTRUCTIONS: Choose units and enter the following:
Weight of Rebar: The calculator returns the total weight of the rebar in pounds. However, this can be automatically converted into other weight units (e.g. kilograms or tons) via the pull-down menu. If OC set to length, the length of the rebar in the mat(s) is return in feet, which can be automatically converted to other length units (e.g. meters or yards) via the pull-down menu. See the Rebar Calculator for more concrete and rebar functions and features. See VIDEO INSTRUCTION for a YouTube video on the use of this calculator.
Rebar is short for "Reinforcement Bars". Rebar is often used inside concrete for added strength, including use in common slabs. This formula provides a length and weigh rebar calculation that is useful in understanding the additional load of the slab added by the rebar steel. It is also useful for calculating the weight of rebar for rebar expense and when considering transport. Steel is dense and heavy. Most vehicles would be considerably overloaded in weight of rebar long before their potential volume is full, which poses a significant safety issue. In the U.S., most pickup trucks are rated at a half or three quarters ton load rating. This rating indicates the safe weight of a load that can be carried. The rebar weight formula can help determine how many trips are required to transport the load of reinforcement steel safely.
The rebar weight algorithm calculates the weight of reinforcement steel bars in a concrete slab. The algorithm calculates the area of the slab, and calculates the length of rebar needed for a rectangular grid within the slab. The grid is specified by the inset from the edge of the slab and the nominal separation between horizontal and vertical rows of rebar (onCenter - see diagram). Once the algorithm calculates the length of rebar, the length is used with the user specified rebar size, and density constants from the vCalc library to calculate the total weight of the reinforcement steel bars.
The user specified parameters are:
The calculation determines the need for an extra rebar using an internal tolerance for for a spacing fraction that exceeds the tolerance with a default of 1".
Rebar is short for reinforcing bar. Rebar is a roughly circular steel bar with ribs used to provide added 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.
In the United States, rebar sizes are in increments of 1/8th inches in diameter. Therefore, size 4 is 4/8th 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.
The above price estimates are based on the current market price of steel and a reasonable markup from raw steel to rebar products.
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:
The vCalc Rebar Calculator Suite is proudly sponsored by BN Products,