The rebar calculator assists in determining the number of rebars required to construct reinforcements in a concrete block and the associated cost of accomplishing this task. In addition to this, it can provide an estimate of the appropriate size for the grid. In this article, you will discover what rebar is, check out the sizes of rebar, and find a guide that will walk you through how to use a rebar calculator.
What is rebar?
In reinforced constructions, a rebar may be either a steel reinforcing bar or a network of steel wires. Its primary function is to retain and fortify the concrete, and it also helps to lessen the stress exerted on it. Reinforcing bars, or rebars, have been used in the building industry for well over 500 years.
Types of Rebar
The size and quality of the rebar you choose for your construction will determine how much support and strength it will provide. It also depends heavily on the rebar’s raw material and the coating. Following are the common types of rebars used.
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Carbon Steel Rebar
The most commonly used material for rebar in both commercial and domestic construction is carbon steel. Although carbon steel may rust in damp environments, this alloy steel is both inexpensive and long-lasting. Working with carbon steel rebar might be dangerous in high-humidity environments or with a lot of moisture in the air.
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Stainless Steel Rebar
This type of rebar is an alternative to carbon steel rebar. However, it is more expensive. Bridges, highways, piers, and other constructions that bear weight rely on these steel reinforcing bars. Stainless steel rebar provides a higher level of safety since it is resistant to corrosion, unlike carbon steel rebar.
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Galvanised Rebar
Galvanised Rebar is an alloy steel alternative that is immersed in a zinc mixture to offer a unique water coating that may prevent corrosion. Similar to epoxy-coated rebar, this material performs well. Galvanised rebar has a 40-fold increase in corrosion resistance and is more durable in transit and installation.
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Glass Fibre Reinforced Polymer Rebar
Fibreglass reinforcing bar, or rebar, is an excellent choice for use in wet environments. Glass fibre rebar has a substantially higher tensile strength than steel rebar and never rusts. Shipping costs may be reduced since aluminium is 75% lighter than steel. In addition to its exceptional mechanical qualities, this unique material is also electrically insulating.
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Epoxy-Coated Rebar
Epoxy-coated rebar is a reliable material for use in damp environments. A thick layer of epoxy protects the rebar from the elements and keeps it from rusting. The epoxy coating on the rebar is easily scuffed and damaged during transport, significantly reducing its ability to prevent corrosion.
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Welded Wire Fabric Rebar
WWF rebar, unlike other common varieties of rebar, is not formed of welded high-strength steel but rather bonded low-carbon steel wire woven into a grid pattern. The grid may be used to strengthen concrete slabs, increasing the material’s tensile strength.
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Expanded Metal Rebar
Expanded metal is a metal mesh with intricate diamond-shaped lines, much like WWF rebar. The mesh originates from a continuous steel sheet that has been meticulously cut and extended. This is the material of choice when the concrete has to be supported by extraordinarily thick plaster. Additional steel rebar is a common choice for pedestrian walkways, although it can’t handle the weight of vehicles or people.
Usage of Rebar
Concrete is a very compressible material, yet it cannot bear the tension. To compensate for this deficiency, reinforcing bars are put into the concrete to support tensile stresses adequately. Rebars carry the full design weight of the buildings and contribute to their endurance by resisting surface fractures and the stress generated by external variables, including temperature and contraction.
Characteristics of Rebar
Due to the reason that concrete and steel both have comparable coefficients of thermal expansion, a structure made of concrete and reinforced with rebar will only experience a negligible amount of stress as a result of the fact that the two materials will expand and contract at the same rate in response to variations in temperature. When carrying and handling these bars, an increased level of caution is required since even the slightest scratch might compromise their resistance to corrosion over the long run.
Placement of Rebars
Rebar cages may be fabricated either on-site or off-site, utilising hydraulic benders and cutters. Ironworkers or steel fixers are used to set the rebars in the concrete. Rebar spacers made of plastic are used to maintain the rebar at the correct distance from the concrete foundation, guaranteeing effective embedment. Electric rebar stacking, welding processes, mechanical linkages, and stringing steel wire are just a few of the methods that may be used to join the rebars together. Rebars may be tied using either epoxy-coated or galvanised wire. Rebars have special steel-reinforced plastic covers placed over their protruding ends for safety reasons.
Significance of Rebar size
A variety of rebar sizes may be required for your project. The tensile stress produced by household and micro projects, including patios or driveways, is often modest. Thus, a rebar with a diameter of 8mm may suffice. Meanwhile, 8mm or larger rebar is required when erecting columns, arches, or sidewalls, and 10mm or larger rebar is recommended for establishing foundations and structural footings to reduce settling.
Large-scale civil engineering projects, such as tunnel or bridge building, sometimes need a larger-diameter rebar, particularly when supporting a greater load or constructing a longer span.
Installing a rebar of the appropriate size is critical to the project’s accomplishment as a whole, and rebar should be changed uniformly at all stages of the endeavour.
Rebar Size Chart
| Imperial Bar Size | Weight (lb/ft) | Weight (kg/m) | Nominal Diameter (in) | Nominal Diameter (mm) | Nominal Area (in2) | Nominal Area (mm2) |
| #3 | 0.376 | 0.561 | 0.375 | 9.525 | 0.11 | 71 |
| #4 | 0.688 | 0.996 | 0.5 | 12.7 | 0.2 | 129 |
| #5 | 1.043 | 1.556 | 0.625 | 15.875 | 0.31 | 200 |
| #6 | 1.502 | 2.24 | 0.75 | 19.05 | 0.44 | 284 |
| #7 | 2.044 | 3.049 | 0.875 | 22.225 | 0.6 | 387 |
| #8 | 2.67 | 3.982 | 1 | 25.4 | 0.79 | 509 |
| #9 | 3.4 | 5.071 | 1.128 | 28.65 | 1 | 645 |
| #10 | 4.303 | 6.418 | 1.27 | 32.26 | 1.27 | 819 |
| #11 | 5.313 | 7.924 | 1.14 | 35.81 | 1.56 | 1006 |
| #14 | 7.65 | 11.41 | 1.693 | 43 | 2.25 | 1452 |
| #18 | 13.6 | 20.284 | 2.257 | 57.33 | 4 | 2581 |
How to Use a Rebar Calculator?
Calculating the rebar shouldn’t be a concern of yours. The rebar calculator eliminates the need for you to worry about any of the complex mathematics involved in the planning stage of the building project. It determines the following values for the parameters:
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Rebar grid dimensions
They are determined by deducting the edge-rebar spacing (also known as the grid spacing) from the slab’s dimensions.
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The total length of rebars required
To compute this, you need to know how many lines of rebar will be installed vertically and horizontally. To illustrate, the number of rows may be determined by dividing the length of the grid by the distance between adjacent rebars. Multiplying this value by the grid’s width will give you the rebars’ overall length.
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Quantity of rebar pieces
If you know the length of a single rebar, you may use that information to make an approximation. It is recommended that this value be rounded up to the next full integer (since it is not feasible to buy, e.g., 0.6 rebar piece).
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Cost of rebars
Simply multiply the number of individual rebar sections by the cost of one individual rebar piece to get the total cost.
Rebar Calculation Formula
It is simple to determine rebar weight by using the following formula, which is the standard one used for the calculation:
Where “L” and “D” represent the length and diameter of the reinforcement bar. Determine the diameter in millimetres and also the length in metres. Your final total will be shown in kilograms (Kg). You may calculate the weight per running metre of the rebar by taking the total and dividing it by the original length of the rebar.
FAQs
What method is used to determine the required quantity of rebar?
The quantity of Rebar required for the foundation must be calculated first. Slab footing Rebar may be easily determined with the help of the footing Rebar calculator. Rebar is typically calculated at a rate of 1 for every 8 inches of footing width. According to this method, you will need two rebars for a footing width of 16 inches, four rebars for a footing width of 24 inches, and so on.
Where exactly should I put the rebar?
Employing the rebar spacing table, determine the distance between the rebars. In addition to this, you need to consult the manufacturer's manual for information on the optimum and other reinforcement spacing. 12-inch rebar spacing is recommended for the majority of the slabbing that will be done. To determine the precise dimensions of each slab individually, use a rebar calculator.
How big should the rebar be for a 4-inch thick slab?
For a slab that is 4 inches thick, the rebar should have a thickness that is equal to one-eighth of the slab. The slab-specific calculator is the best tool for determining the size of the Rebar.
Does the concrete need gravel subgrade?
To properly support a concrete slab, foundation, or patio, you must use gravel. Gravel's primary value lies in the fact that it may serve as a foundation for other materials, such as concrete. In most cases, the gravel is utilised to assist the drainage, preventing water from gathering up in one area. Calculations using concrete Rebar may be used to determine the size of the needed grave.
What is the key difference between rebar sizes 3 and 4?
The lowest yield strength distinguishes rebar sizes 3 and 4, the latter of which is more often used. Compared to the rebar with a strength rating of 4, the lowest yield strength of the rebar with a rating of 3 is 6,600 pounds. Rebar with a yield strength of 4 is stronger than 3 rebar by more than 78%. One may determine the rebar's minimum yield strength using a slab Rebar calculator.
