Everything You Need To Know about the Reinforcement of ...

Concrete, renowned for its durability, ease of use, and fire resistance properties, is a staple in global construction projects.

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However, concrete’s inherent fragility poses a significant challenge; it is exceptionally brittle and can fracture quickly under various types of force.

This is where REBAR enters the scene! Commonly referred to as Reinforcing Bar, it serves as a crucial component in enhancing the structural integrity of concrete.

In this article, we will delve into the importance of reinforcement and provide step-by-step guidance on how to effectively use rebar to bolster concrete.

Let’s dive right in!

Rebar used for casting concrete slabs

Why Does Concrete Require Rebar?

Reinforcement is often essential for concrete structures.

Although concrete possesses significant strength in certain aspects, it bears some serious vulnerabilities. To grasp these vulnerabilities, we must first explore the various types of stress that can act upon objects.

Different load types that can act on a structure

1. Compressive stress

Compressive stress refers to a force applied to an object that causes it to shorten or compress. For instance, when an elephant steps on your toe, that pressure results in compressive stress.

1. Shear stress

Shear stress occurs when forces are applied at right angles to one another. For example, if you clasp your fingers together and pull against yourself, you are experiencing shear stress.

1. Tensile stress

Tensile stress is the force that stretches or elongates an object. When you stretch a rubber band by pulling both ends apart, you apply tensile stress on the band.

Concrete excels under compressive and shear stress but falters under tension. Indeed, the tensile strength of concrete comprises only about 10-15% of its compressive strength.

12 Meter rebar in a construction site

Our Good Ol' Mate, Rebar

Rebar effectively reinforces concrete by forming a composite material.

These rods come in various lengths and diameters, often featuring ridges or bumps that allow for better bonding with the concrete.

Typically made from steel, rebar is both strong and has thermal expansion properties similar to concrete, making it an optimal choice for reinforcing structures.

What Does Rebar Do For Concrete?

As previously mentioned, concrete handles compressive stress effectively but struggles with tensile stress.

This issue arises because nearly every structure encounters multiple forces simultaneously.

For instance... The Classic Beam

When a beam experiences compressive stress on its upper side, it begins to bend.

Consequently, the stretching of the beam's bottom occurs as a result of this bending, creating a scenario where the bottom experiences tensile stress.

Tension Vs Compression

Since concrete is not suited for handling tensile stress on its own, it does not serve as an ideal structural material in isolation.

However, the addition of rebar leads to two significant outcomes.

First: Incorporating rebar into concrete creates a composite material that withstands various stresses. The rebar counteracts tensile forces, while the concrete effectively absorbs compressive stress. The resultant composite is remarkably strong.

In fact, concrete that is reinforced with rebar can withstand nearly double the breaking point of concrete without rebar.

Second: The presence of rebar serves as an early warning system for when concrete is nearing failure.

Pure concrete is described as brittle; when subjected to pressure, it can unexpectedly shatter without any warning.

Conversely, when integrated with rebar, concrete becomes ductile, showcasing signs such as fissures and cracks as pressure escalates.

This characteristic proves beneficial in two essential ways:

• Concrete reinforced with rebar maintains strength despite minor cracks
• There are visible warning signals before the concrete fully fails.

Rebar combined with concrete to create a strong composite material

When is Rebar Necessary?

Concrete surfaces that endure heavy loads, such as large trucks or constant traffic, should always incorporate rebar reinforcement, and any structural concrete elements, like walls in edifices, must also include rebar.

Is it mandatory to use rebar in every single concrete project?

Not always.

For instance, if you are pouring concrete for a driveway meant for a minivan, extensive rebar reinforcement might be unnecessary.

Nevertheless, when in doubt, it’s advisable to use rebar!

Regardless of the scale of the concrete pour, rebar will enhance the strength of your structure. At the very least, it will greatly reduce the prevalence of cracks in the concrete.

Bonus tip: If you’re working on a smaller residential concrete project and steel rebar appears to be excessive, consider utilizing welded wire mesh instead. Mesh, being thinner than rebar, provides less strength, but is also a more cost-effective option.

Welded Wire Mesh in concrete

7 Main Types of Rebar

As mentioned, welded wire mesh is a type of rebar appropriate for particular applications.

You may be curious: Are there other types of rebar appropriate for specific situations?

Absolutely!

Below are several different types of rebar that you may consider using.

Carbon Steel Rebar

This is the most widely used type of rebar, often referred to as a "black bar". It boasts remarkable versatility but tends to corrode more readily than other types, rendering it less desirable in humid environments or structures frequently exposed to moisture.

Welded Wire Mesh

Welded Wire Mesh (WWM) comprises numerous steel wires arranged at right angles and welded together at all crossings.

It's particularly useful in well-compacted ground slabs, and a sturdier fabrication may be applied in walls and structural floor slabs. This material is frequently employed in road pavement, box culverts, drainage structures, and smaller concrete canals.

Glass Fiber Reinforced Polymer

Similar to carbon fiber, GFRP rebars are immune to corrosion under all conditions, but this advantage comes at a hefty price, as these rebars can be ten times the cost of epoxy-coated alternatives!

Nonetheless, GFRP rebars have emerged as a significant advancement in reinforced concrete technology due to their benefits over traditional steel rebar, including resistance to corrosion, lighter weight, and high tensile strength. These features make them appropriate for concrete structures in harsh conditions, such as bridges, tunnels, marine facilities, and industrial sites.

Epoxy-Coated Rebar

Epoxy-coated rebars are essentially rebars that have been coated with a thin epoxy layer, enhancing their corrosion resistance by up to 1,700 times compared to standard carbon steel rebars. Consequently, they are often employed in environments exposed to saltwater or where corrosion is a looming concern.

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Additional resources:
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Robert Caputo covers great findings and research discussing the controversial topic of epoxy-coated rebar and its effectiveness in protecting against corrosion in this article over here.

Galvanized Rebar

Galvanized Rebars are forty times more resistant to corrosion than regular carbon steel rebars and are considerably less susceptible to damage than epoxy-coated variants.

This makes them an excellent alternative to epoxy-coated rebars if you need a solution that minimizes corrosion risks.

Unfortunately, Galvanized Rebar is about forty percent pricier than epoxy-coated rebar.

Stainless Steel Rebar

Typically, stainless steel rebar comes with a steep price tag—about eight times that of epoxy-coated rebar.

However, for specific applications, stainless steel rebars offer significant advantages, being 1,500 times more resistant to corrosion compared to regular black bars. Additionally, stainless steel rebars are also flexible enough to be bent on-site, which is quite convenient.

European Rebar

The main advantage of European Rebar lies in its affordability. Primarily made of manganese, European rebar is cost-effective and easy to manipulate.

However, it is generally not recommended for areas prone to earthquakes or for construction that necessitates substantial structural stability.

Rebar comes in a variety of diameters sizes and lengths

Choosing the Right Size of Rebar

A myriad of steel rebar sizes, grades, and types are available to accommodate different structures. Standard rebar sizes can fluctuate by country, covering both metric and imperial sizing.

In Australia, for instance, various diameters of rebar are accessible, including 6mm, 10mm, 12mm, 16mm, 20mm, 24mm, 28mm, 32mm, and 36mm.

Most suppliers such as Instant Steel Solutions offer stock lengths of 6m, 9m, 12m, 16m, and 20m.

In essence, the size of the rebar necessary for a particular task depends on the required strength. Greater strength necessitates larger pieces of rebar.

Consulting with structural engineers or skilled professionals is advisable, as they can evaluate your project’s specific requirements. Their expertise can guide you in making well-informed decisions regarding rebar size and placement.

Concrete Pour

How to Place Rebar in Concrete

After determining the appropriate type and size of rebar, the next step is placing it correctly in the concrete!

There isn’t a uniform method for rebar placement since many variables come into play specific to each construction project. For example, how much force will the concrete endure? Will it be subjected to freezing and thawing cycles?

If you are undertaking a simple pour around your property, it's prudent to consult with a local concrete contractor to learn proper rebar placement techniques.

For larger commercial pours, rebar specifications should be communicated within the blueprints, which have been precisely structured by an engineer who has calculated the requisite amount and spacing for rebar, so adhere to these instructions closely.

Attention to detail is imperative in rebar placement; poor technique could compromise the concrete's structural integrity.

For instance, if the specifications entail rebar every 4 inches, it’s vital to ensure three bars are placed for each 12 inches of the form.

A slight error, such as spacing the bars at 5 inches rather than 4, might diminish the product’s strength by as much as 20%!

Cut and Bend Rebar

You may know exactly how far apart your rebar should be, but what if your bars are too long? Or what if the design requires bent rebar?

Some rebars come pre-bent; however, typically, you might need to cut and bend rebar for proper placement.

Note: At ASPAC ALLIANCE STEELS SDN BHD, we provide CTL (Cut-to-length) and C&B (Cut and Bend) Rebars with minimal to zero wastage.

With the right tools, cutting and bending rebar is straightforward.

First, concerning cutting rebar, various tools can be employed for this task.

A hacksaw or bolt cutter is suitable if the rebar is thin enough and you're not cutting a large volume. For significant jobs, an angle cutter with a cutting wheel is great.

Bending Rebar

With all these tools, keep in mind that cutting through the entire rebar isn’t necessary. You only need to cut halfway, allowing you to easily snap it in half.

Use this tip to save yourself a ton of time!

Occasionally, rebar must also be tied. If you wish to learn more about tying rebar, consulting with a local contractor would be a prudent starting point.

Final Note

Concrete is a vital construction material, yet without rebar, it loses much of its effectiveness.

Rebar and Concrete

As we all know, size matters—especially when selecting the appropriate size of rebar to suit your project.

If you require a consistent supply of rebar in the Asia-Pacific region, don’t hesitate to reach out to ASPAC ALLIANCE STEELS SDN BHD to discuss how we can fulfill your requirements.

We hope you found this article informative, and we look forward to sharing more insights with you in the future!