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This article explains why you might need to bend rebar, as well as teaching you five possible methods to complete this task. It also covers the definition of rebar, and how it is used.
What Is Rebar?
Rebar is short for ‘reinforcing bar’. This term usually refers to solid steel rods used to provide reinforcement to masonry and concrete and improve their performance under tension. Other options for rebar include glass fiber, carbon fiber, and even bamboo. This article focuses on the form of rebar known as ‘reinforcement steel’ or ‘reinforcing steel’.
Concrete has high compressive strength, but low tensile strength. Smooth and ridged versions of rebar are widely available, and the raised surface-level ridges help concrete bind to the rod or cage.
Rebar can refer to the individual rods, or to a cage built of multiple rods. Masonry and concrete reinforced with rebar is less likely to crack when exposed to pulling or bending.
Un-bent rebar is used for the main reinforcement bars in the construction of rebar cages.
When rebar is bent into a circle or rectangle and used to hold main reinforcement bars together, this is called a stirrup.
Corner bars are typically bent to a 90 degree angle, and are used to reinforce the corners of concrete slabs or to tie together horizontal and vertical reinforcement bars.
How To Bend Rebar By Hand
Unless you’re a competitor in a strongman competition, you will need a few lengths of pipe to assist you in bending rebar by hand.
- Gather your materials. Source two lengths of pipe that are wider in diameter than the rebar you intend to bend.
- Arrange the pipes. Slip the rebar into the two lengths of pipe. Move them close together, so that only the portion of the rebar you want to bend is exposed.
- Grasp the rebar. Hold the outer ends of both pipes with your arms out in front of you and your palms facing down.
- Bend the rebar. Use your latissimus dorsi muscles to bring your palms and elbows toward the centerline of your body.
- Measure the bend. When you get close to the desired angle, measure the bend with a carpenter’s square. Rebar loses strength each time you bend it and unbending rebar further decreases its strength, so be careful not to bend the rebar past the point you desire.
How To Bend Rebar With Hickey Bars
Hickey bars (also called hickey tools) have a three point grasping device that holds cylindrical material such as rebar or pipe. Two hickey bars are needed to bend the rebar. This method is not as precise as using a hand-operated or power bender.
- Mark your intended bend. Wrapping a piece of masking tape around the part of the rebar you want to bend helps avoid mistake bends.
- Secure the rebar. Insert the rebar into pliable ground or hold it using vice grips.
- Attach the first hickey bar. Fit the rebar in between the three pins at the head of the hickey bar.
- Attach the second hickey bar. Place the head of the other hickey bar around the rebar, as close as possible to the point you want to bend. The long handles should cross each other, forming an X shape.
- Bend the rebar. Apply leverage to the second hickey bar, creating torque at the bend site.
- Check your bend. Stop frequently to measure your progress with a measuring square. Rebar used to provide structural integrity should not be unbent, so measure frequently as you approach the desired angle.
How To Bend Rebar With a Manual, Portable Rebar Bender
Manual rebar benders are more expensive than hickey bars, but bend more easily and precisely. Choose this method when you need to bend multiple bars of rebar to a precise angle.
- Place the rebar bender on a sturdy, flat surface.
- Set the dial to the number that matches the diameter of the bar you intend to bend, measured in inches.
- Thread the rebar through the cam of of the rebar bender
- Use the handle to bend the rebar up to 90 degrees.
- To make a stirrup, repeat the process four times to create a square or rectangle.
How To Bend Rebar With a Powered, Portable Rebar Bender
On the job-site, concrete professionals use portable rebar bending machines that are powered by electric and hydraulic power. They eliminate the need for manual force and bend rebar to precise angles.
- Set up your workspace. Place the rebar bender on a sturdy and flat surface.
- Connect the rebar bender to power. A generator can be used for non-powered site work. When used near power, a regular 110-volt outlet can be used.
- Insert the rebar. Place the rebar in the grip of the machine.
- Adjust the settings. Use the bending angle marker to indicate the desired bend, measured in degrees.
- Bend the rebar. Remove your hands from the work area and stand out of the way of the rebar. Turn on the machine and allow the hydraulic press to do its job.
- Remove the rebar. The precision bending capability of these machines means you should not need to double check the angle of the bent rebar. Unlike manual benders or hickey bars, power benders are able to bend rebar up to 180 degrees in a single press.
Professional Rebar Bending
Pre-job site, professional-level rebar bending is done with an expensive, advanced machine. It uses pulleys and gears to bend rebar. Index bars can be placed in holes at various intervals to bend rebar to a precise angle.
These machines are large and prohibitively expensive for most DIYers. However, they are capable of bending multiple rods at one time. They can bend to the left or right and are operated using a footswitch.
Which Method Should I Use to Bend Rebar?
If you’re wondering which method is best for your situation, here is a quick cheat sheet:
- Use the hand-bending method for single pieces of rebar with a diameter of up to ½ inch.
- A hickey bar can be used to bend rebar up to one inch in diameter.
- For manual rebar benders, stick to rebar less than two inches in diameter.
- Portable hydraulic-electric rebar benders can handle rebar up to three inches in diameter.
- For anything stronger than Grade 60 rebar, or more than three inches in diameter, a professional rebar bending machine is required.
Rebar Grading and Labeling
These steel rods are graded by their yield strength, measured in the pounds per square inch (PSI) they can withstand without becoming deformed.
The most common grade of rebar is grade 60, which has a minimum yield strength of 60,000 PSI and a tensile strength of 90,000 PSI or higher.
Grade 40 is also frequently used, and can withstand deformation at up to 40,000 PSI, and has a minimum tensile strength of 60,000 PSI.
Other grades include 33, 50, and 75. The higher the grade, the greater the yield and tensile strength.
The company, grade, and composition of the rebar is typically stamped onto the bar. The ends are also color-coded. White paint indicates Grade 33. Grade 40 rebar has yellow paint on one or both ends. Grade 60 rebar is distinguished from other grades by it’s green painted ends.
If both ends of the rebar are the same color, it is non-weldable. When one end is marked with red paint, this indicates that the rebar is suitable for welding.
There are five main ways to bend rebar, all of which function by providing torque. They are; bending by hand, using hickey tools, purchasing a portable rebar bender (manual or powered), and using a professional rebar bending machine. Bending rebar decreases its strength at the bend.