Rebar: The Ultimate Guide to Steel Reinforcement

Even though most rebar is hidden from public view, it plays a vital role in securing structures such as bridges, buildings, roads, and pretty much anything made from concrete.

It is also used extensively in the construction of house/building foundations.

Without it, many of the concrete buildings, bridges, and structures we take for granted would not be possible. Like any metal product, there are many different types of rebar, and many ways to use and install them. Read on for more information about steel reinforcing bars.

What is Rebar and Why is it Essential for Concrete Structures?

Although concrete is strong in compression, it is relatively weak in tension. Rebar or reinforcing bar is used inside most concrete products, especially when they are subject to high loads.

In practical terms, this means a concrete object will be able to withstand significant force when compressed, but not if it’s used in something like a bridge, lintel or beam, as it will break apart when stretched.

Different Types of Rebar: Choosing the Right Steel for Your Project

Many different types of rebar are available, from different sizes, grades, and textures, to paint finishes and even non-metals.

Deformed/Smooth Rebar

In some cases, a smooth bar, also known simply as black bar is used as reinforcement.  Deformed steel bars are far more common, though. This is because the ridges offer more contact with the concrete and reduce the chances of the bar slipping in the concrete.

Reinforcing Mesh

A type of rebar often used when pouring large quantities of flat concrete, such as machine or structure bases, the tops of bridges, etc, is rebar mesh sheets.

This is made similarly to ordinary weld mesh, but typically uses deformed rebar instead of smooth wire. It is a cost effective method of creating a large area of strengthening.

Rebar Sizes and Grades: Understanding Specifications for Optimal Strength

Diameter

Typical rebar comes in sizes from 8mm to 40mm in diameter. In Europe, these are prefixed by a T, so they are referred to as T10, T12, etc. Not every increment is available, so be sure to check the table below for specifics.

*US imperial bar sizes are added for an approximate comparison, though double check any figures before using this chart to compare between the types

Rebar Material

A manganese steel alloy is sometimes used, and commonly referred to as “European Rebar”; this is easier to bend but does not have as high tensile strength. This means it’s generally not to be used in high load structures or those subjected to extreme weather events.

TMT rebar is the highest strength rebar commonly used on construction projects. It undergoes heat treatment that greatly increases its tensile strength, hence its name: Thermo Mechanically Treated.

In some cases, GFRP (glass fibre reinforced polymer) or stainless steel rebar is used. Naturally, these are both much more expensive than steel, but offer lightness and corrosion resistance, respectively. The latter is often used in projects exposed to seawater.

Rebar Grades

As with most metal products, there are multiple grades of rebar, with higher grade ones being suitable for higher strength applications and consequently more expensive than the lower grades. These are the grades commonly used in North America:

• Grade 40 – Used for light-duty applications such as driveways and residential slabs – 40ksi of yield strength
• Grade 60 – Used for both residential and commercial construction projects, such as office buildings, utility infrastructure, etc – 60ksi of yield strength
• Grade 75 – high strength rebar used for bridges, dams, and other high consequence structures. 75 ksi of yield strength

Rebar Installation Techniques: Best Practices for Concrete Reinforcement

Rebar installation and placement is an entire trade on its own; typically, the exact placement and size of the rebar will be determined by the structural engineer when the building plans are drawn up. These are some of the common key elements to consider:

• Placement – relatively tight tolerances are placed on the location of rebar placement, as the spacings are crucial to the concrete performance – follow your structural engineer’s drawings to the letter!
• Encasement – the rebar is protected from rust by the concrete, and should be encased by a minimum amount depending on the type of concrete, rebar and the environmental conditions
• Bar supports – when pouring, the bars need adequate support to ensure that sagging and displacement when the concrete is added are minimized. This is part of the reason for tying.
• Tying – Wire ties are used to ensure the rebar stays in position when the concrete is poured. Rebar tie wire can be bought in both cut lengths for manual application or reels for machine use

Rebar Cost and Maintenance: Maximizing Lifespan and Minimizing Expenses

While rebar is not exactly cheap, the cost of buying and installing it prior to a pour is nothing compared to the expense of having to rework for incorrect type, placement or corrosion.

For this reason, rebar is also available in corrosion-protected types. We’ve touched upon stainless and polymer rebar, but there are also a number of carbon steel options:

• Epoxy rebar – this is coated in a flexible, durable epoxy coat in the factory, giving good corrosion resistance
• Galvanized rebar – In certain situations, more corrosion resistance is needed; galvanized rebar is made in the same way as any galvanized product is, by dipping in molten zinc. This produces an excellent corrosion-resistant layer.