Reinforcing bar or rebar is the standard for buttressing concrete, and you see it in quite many buildings as they’re being constructed. Yet is rebar necessary for every concrete project or can you skip the reinforcements in some instances?
No, you don’t always have to reinforce concrete, especially when the depth of the concrete is under five inches. That includes concrete projects such as pouring floors, driveways, and pathways.
In this article, we’ll further explain when you should and shouldn’t use rebar in a concrete project. We’ll also discuss the types of rebar so that if you need it, you’ll know what to look for.
Let’s get started.
When You Need to Reinforce Concrete
Rebar, given that the word bar is in the name, is typically stainless steel columns or bars that become the skeleton of a structure. Using that analogy, the concrete would be the flesh. You don’t see rebar in a concrete building just like you can’t really see your own skeleton outside of your teeth.
When should you reinforce concrete? As we touched upon in the intro, for any concrete project that’s more than five inches deep, you should strongly consider using rebar. This will benefit the structural integrity of the building.
You might be wondering what the point of rebar is. Isn’t concrete plenty steady on its own? Sure, but concrete can deteriorate in a variety of ways. Let’s talk about those now.
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Cracking
From the pouring to the curing stages, working with concrete is a precise thing. If you make a mistake, the concrete can crack when cured. Aging can also cause concrete to crack, as can thermal contractions from temperature changes.
Depending on the extent of the cracks, the damage to the concrete can be minor or more serious. Cracks should be repaired upon detection to prevent the structure from becoming more damaged.
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Delamination
When the concrete fractures and turns into layers, this is known as delamination. If the rebar corrodes and then the concrete atop it cracks, this can cause the concrete to delaminate as well.
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Spalling
Should delaminated concrete go unrepaired, then it will begin to spall. Spalling is simply more advanced fragmentation of concrete so it’s even weaker. As the concrete freezes in the cold weather and then thaws out, the layers and fragments can snap off.
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Erosion
Yes, concrete can erode like soil, and the cause is the same: moving water. All the friction of the particles and the water against the concrete wears it down. Gravel and sand that travel through the rushing water can worsen concrete erosion.
Since rebar can corrode, reinforcing concrete doesn’t necessarily prevent the above problems completely. However, these issues could lead to your entire concrete structure becoming unstable without reinforcement.
Instances When You Don’t Need to Reinforce Concrete
That doesn’t mean that foregoing concrete reinforcement is necessarily an irresponsible decision. For concrete projects with a depth of fewer than five inches, you can skip the rebar and still have a stable concrete structure.
Concrete floors for indoor or outdoor use are one such example. Landscaping pathways are another case in which concrete doesn’t need reinforcement. Driveways usually don’t require rebar either, although there are some exceptions.
For instance, let’s say you’re pouring a concrete driveway. If yours is a driveway intended for residential use, then there’s no need for any rebar. However, for driveways that accommodate weighty vehicles like commercial freight trucks, you might consider adding reinforcement before pouring the concrete.
The Types of Rebar Used to Reinforce Concrete
If your concrete project requires a rebar, you have plenty of reinforcement types to select from. Here is an overview of the kinds of rebar available.
Stainless Steel Rebar
The standard rebar is stainless steel columns. Stainless steel is heavy so it can be a great support when pouring concrete. Today, stainless steel is more recyclable than ever, so it’s considered a green material.
Resistant to impact damage, stainless steel is even durable when the temperatures change. It does still expand and contract, but its application in cryogenics proves its ability to withstand low temps.
High temperatures also don’t weaken stainless steel. If the steel is nickel alloy or chromium-graded, then it’s even resistant to fire. Manufacturing stainless steel is surprisingly versatile, as the material is often fabricated, machinated, bent, and welded.
One of the biggest benefits of stainless steel rebar is that it doesn’t corrode. We talked earlier about how corroded support structures can be quite detrimental to the soundness of a concrete building. When you choose stainless steel rebar, you can be assured that the metal will be in great shape for years to come.
Epoxy-Coated Rebar
The next best thing to stainless steel rebar is epoxy-coated rebar. Although it’s not corrosion-proof, this type of rebar is less likely to corrode. That’s why its nickname is corrosion-resistant rebar.
Factory-produced epoxy coats the stainless steel to maintain the quality of the metal. The epoxy coating is usually green, but since the rebar isn’t visible anyway, the color doesn’t matter so much.
Even if the concrete structure happens to crack, epoxy-coated rebar doesn’t buckle. The building will still require repairs, but it would be structurally secure enough until those repairs could happen thanks to the rebar.
Sheet Metal
For concrete-pouring applications such as stairs, roofs, and floors, using metal bars as reinforcement is excessive. If these structures need any rebar at all, they’ll be supported by sheet metal.
This thin metal strengthens the above structures, although it’s not necessarily the most durable type of rebar. It could also corrode depending on the type of metal used to make the sheets.
Welded Wire Fabric
Another type of thin rebar is welded wire fabric or mesh. Like sheet metal, this wire fabric is used only for specific projects such as for slab-on-compacted-ground or slab-on-ground concrete pouring.
Tips for Pouring and Reinforcing Concrete
Now that you’ve determined that your concrete project requires rebar and you’ve decided which type is the most suitable for your budget, here are some tips that will come in handy as your project gets underway.
Ensure You’re Starting with a Good Base
If you don’t want your concrete foundation to crack now or three years from now (or later), then you must create a solid base for the concrete. Depending on the type of concrete project, this base will be at least six inches deep. In parts of the country where the weather is colder, increase the base depth to 10 or even 12 inches.
What can your base be made of? Soil, gravel, or sand is fine, whatever is compactible. You can compact the base layer with a vibrating plate compactor. The rule of thumb is this: anytime you increase the base by two inches, go over the entirety of the base with the vibrating plate compactor three times.
Keep the Base Moist
When compacting the base, if it doesn’t want to give, that’s because it’s too dry. Using a gardening hose, moisten the base. Then you can install the rebar. Another benefit of wetting the base besides making it more pliable is that it extends the curing time so your concrete will be even more durable.
Pour Concrete in Sections
Pouring concrete is not like putting icing on a cake. You can’t just squeeze out a huge dollop in the middle and then spread it. Concrete dries or cures, and by the time you go to move the concrete to other sections of the structure, the big dollop has started to solidify and is now unwieldy to move.
What you should do is divide the base of your concrete structure into sections, perhaps four sections. There’s no need to make any kind of dividing marks; just remember in your head where you want all four sections to be.
Then, go section by section, filling with concrete and spreading. This will ensure a more even result and save you the pain of trying to disperse a giant concrete blob in the middle of the base.
Use a Concrete Placer to Even out Concrete Over the Rebar
How do you spread concrete? With a concrete placer, which sort of looks like a snow shovel but is a lot narrower and wider. You simply push the concrete after pouring it so it evenly covers the rebar. Repeat this for each section of your base.
Know the Hand Signals
Pouring concrete is not a one-person job. Someone will be in the truck and another person will oversee how much concrete is coming out. Since the truck is not quiet, you probably won’t be able to verbally communicate with the driver. Instead, you’ll have to use hand signals.
To tell the driver to back the truck up, put your hand out and pull your fingers inward, sort of like telling someone to come here. Gesture with your fingers and your wrist, but don’t space your fingers apart while gesturing.
When the truck is in position, make your open palm into a closed fist. This tells the driver to stop. Then, when you’re ready for the driver to release the concrete for pouring, lift your index or pointer finger and begin rotating it in a spiral shape.
If you want them to stop, put your hand up by your neck. Your fingers should be closed and your hand open. Make a quick slicing motion once.
Final Thoughts
You don’t always have to reinforce concrete, but if your structure will be more than five inches deep, it’s the best course of action. Using rebar can support and strengthen concrete structures so you might get more years out of them!