How Much Rebar Do I Need?

What supports concrete, and how much support do I need?

How Much Rebar Do I Need?

A lot of my customers ask me  “Should we put thicker reinforcement in our concrete? 

It’s a common misconception that rebar will reduce cracking – the truth is that it really depends on the foundation the concrete is being poured on. 

As long as your new concrete is placed on well-compacted soil, the concrete we can consider the foundation sturdy enough for the concrete to last a long time.  As long as you have allowed your new concrete to expand and contract with properly placed expansion joints, then there is a good chance rebar isn’t really necessary.

Ok, so let’s dive deeper.

The most important physical property to remember about concrete is its mechanical strength in compression. 

Why Does Concrete Need Reinforcement?  

Concrete itself has little or no tensile strength, to begin with…

 Reinforcement steel placed in concrete gives it the tensile strength required to resist those forces that place your concrete in tension.  

For instance, the soil in most of the gulf coast states consists of expansive clay. When clay gets wet, it expands and contracts in a matter of days.  When it contracts, it will eventually leave a void under your concrete over time. 

When a load force is placed on top of the concrete, the soil beneath it must be able to absorb or resist that same load force. 

If there is a void, the concrete will begin to take on tensile loads.

Having a rebar will help resist that load.  

That’s the primary reason for the rebar.  AND, the rebar MUST be placed in the center of your new concrete for it to be effective.

Applying Rebar to Your Concrete Driveway

By far the most common application where rebar is necessary is for driveways! Driveways are large construction projects that require precise measurements for maximum safety and longevity. Ideally, the concrete should be at least four inches thick. Additionally, the rebar should be placed in a perpendicular pattern, but too close to the edges. Here at Sam the Concrete Man we use 3/4 inch rebar for most concrete projects. Learn more about our concrete driveway projects here. 

Find a Concrete Contractor Near You

Pouring concrete by yourself can be a daunting task, especially when considering whether you need to have rebar. Make sure you do it right the first time to avoid costly repairs. Here at Sam the Concrete Man, we serve everywhere from Denver, Colorado to New Jersey on the East Coast. 


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