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What is Reinforcing Steel?

Lori Kilchermann
Lori Kilchermann

Reinforcing steel is a material used to strengthen concrete. Woven into a maze and placed inside of forms or suspended to allow the reinforcing steel to lie in the center of a poured slab, the iron rod gives added strength to the already strong cement. Commonly called by the slang name "re-bar," the steel has a surface of raised lines and patterns to allow it to stick tightly inside of the poured concrete. Many times, the reinforcing steel is woven into a multi-layered mat to give an inner strength otherwise unobtainable to concrete or cement work.

Made of low-grade iron, this steel is not very difficult to bend. This allows iron workers to shape the long rods into horseshoe-like configurations to reinforce cement pillars. The long sections of iron rod are typically tied together with small-diameter wire and set at critical depths within the cement forms to allow the cement to flow both over and under the steel re-bar. By placing bends in the bar, it is locked into the cured cement and unable to shift position. This method of reinforcing the concrete will actually allow the concrete to bend slightly under pressure without cracking before it returns back to its original shape.

Steel reinforcing bars, or rebar, are inserted into concrete to provide additional support.
Steel reinforcing bars, or rebar, are inserted into concrete to provide additional support.

Iron workers commonly create intricate skeletal structures out of the reinforcing steel when it is to be used inside of concrete pillars or bridge pilings. Once the iron structure is complete, a wooden or steel form is placed around it prior to the cement being pumped in around it. Large vibrating rods are plunged deep inside of the reinforcing steel-lined concrete to vibrate any air bubbles out and fill in any voids. This creates a very solid piece of cement that will not have any potentially weak areas inside. Flat metal straps are often used to center the skeleton inside of the forms so it can be easily cut and removed when the form is to be taken off the cement.

Ferroconcrete is a type of concrete that is reinforced with metal bars or grids.
Ferroconcrete is a type of concrete that is reinforced with metal bars or grids.

Often, the re-bar will be treated with a chemical or paint to help in the prevention of rust and corrosion. The treated iron will survive much longer inside of the concrete and will not eventually rust away, leaving voids and holes inside of the cement that may weaken it. When removing reinforced concrete, the reinforcing steel is commonly cut with acetylene torches after the concrete has been broken up by a jack hammer. This allows workers to cut the material into easily managed sizes for disposal.

Discussion Comments

wavy58

@lighth0se33 – Congratulations on your soon-to-be-beautiful driveway! The thickness of the concrete all depends on what type of vehicles you will be driving on it. If it will be small cars and light trucks, the thickness can be six inches. I highly doubt you will be driving large trucks on your driveway, anyway.

The chairs were about three inches, so the reinforcement steel would be right in the middle. All you need to do is tie the steel together with a thin wire. You will want to keep it about two inches away from the edge of the form.

We did put some stress joints in there to prevent ugly cracks from forming across the driveway. A stress joint is a controlled crack. It's a small piece of steel specially designed to leave a uniform crack across the driveway, and it looks so much better than a jagged eyesore.

lighth0se33

@wavy58 – I'm about to put in a concrete driveway. I have a couple of questions that you might be able to answer for me.

How thick was your concrete, and how tall were the chairs that you put the mesh on? Did you have any problems with it cracking later on?

I have heard of putting joints in the concrete so it doesn't crack all the way across. How far apart would those need to be?

I'm hoping to start my project this spring. I just wanted to get some advice from someone who has done this before prior to embarking on this task.

wavy58

I have done concrete work in the past here and there, whenever my friends needed help on a project. My most recent one involved my neighbor, who wanted to put in a concrete driveway.

We formed everything and we got some reinforcing steel mesh. The price of that mesh depended on the current steel price, which wasn't too bad, so we decided to do my driveway, also.

We put the steel down on chairs, which are small metal platforms that hold the mesh off of the dirt and put it in the middle of the concrete, where it is most efficient. Our driveways were not that long, so it only took two weekends to do each one. The hardest part was digging down far enough to where it would be level with the yard.

orangey03

After I moved out of New York, I got a job at a construction company, and we were in charge of building bunkers and blast walls for a rather large ammunition company. The people who installed the rebar were called “rodbusters.” They would hang on the sides of the metal, 10 to 15 feet up in the air, steadily working their way up as we were building forms for the concrete underneath them.

When they got finished, they would go to the next blast wall, and we would start pouring the concrete in the one they just finished. I actually had the wonderful task of handling the vibrating hose, and it is not as easy as it looks. After a few hours, you want to throw that thing as far as you can.

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    • Steel reinforcing bars, or rebar, are inserted into concrete to provide additional support.
      By: wittybear
      Steel reinforcing bars, or rebar, are inserted into concrete to provide additional support.
    • Ferroconcrete is a type of concrete that is reinforced with metal bars or grids.
      By: Kadmy
      Ferroconcrete is a type of concrete that is reinforced with metal bars or grids.
    • Concrete is frequently poured over a steel rebar grid, which increases the strength and durability of the pavement.
      By: podsolnykh
      Concrete is frequently poured over a steel rebar grid, which increases the strength and durability of the pavement.