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Perhaps the most ubiquitous of all building materials, rebar is familiar to all of us, even the general public. Short for reinforcing bar or reinforcement bar, rebar is a vital component of almost every modern construction project. But what exactly is it and how is it used? With developments coming all the time in construction techniques and materials development, what does the future hold for rebar?
In this article, we hope to provide answers to all of these questions and more, to provide the ultimate guide to steel reinforcement.
What Exactly Is Rebar?
As mentioned above, the word rebar stands for reinforcement bar, and in short, it is a steel rod that is used to provide tensile strength to concrete structures and slabs. Whilst concrete on its own has excellent compressive strength, meaning it can withstand heavy loads, it does not have adequate tensile strength, which means that it could be subject to cracking or even failure when subjected to lateral force.
Rebar comes in many different types and grades, each suitable for different construction projects. Rebar can also be formed into sheets of multiple rods, to produce reinforcement mesh, which can be used to quickly cover a large surface area in a cost-effective way. Generally, it is supplied with surface deformations that help to provide a strong bond with the poured concrete.
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A Brief History of Rebar
Concrete has been used in construction for centuries, with the Coliseum in Rome being an excellent example of a concrete foundation dating back to 70 AD. Rebar has been in use in masonry building since at least the 15th century, with many French chateaux and British stately homes being excellent examples of steel framed masonry builds.
However, when it comes to combining concrete and rebar for construction projects, things are altogether more recent. It was not until the middle of the eighteenth century that concrete was routinely reinforced with steel for construction. Both Joseph-Louis Lambot and Joseph Monier are credited with the early development of reinforced concrete in France, and soon after their work, Ernest L. Ransome developed a twisted iron bar for reinforcing concrete – paving the way for the rebar that we all recognise today. Further developments followed quickly, and by the early part of the nineteenth century, reinforced concrete was in use extensively. One of the architectural changes that the adoption of rebar brought about was the skyscraper, as reinforced concrete gave the world a means to build higher than was previously thought possible or cost-effective using masonry alone.
Advantages of Using Rebar
The obvious benefit of using rebar in a construction project is that it provides significant tensile strength. Without it, buildings could be at risk of cracking or complete failure and collapse. Other advantages of using rebar to provide the required tensile strength in construction projects include:
- Steel has similar thermal expansion coefficients as concrete, which means they expand and contract at the same rate. That makes steel rebar the perfect partner for concrete.
- Steel bars are easy to shape, weld and position, and they are robust enough to withstand handling during construction and transportation.
- Rebar is readily available in all geographic regions, and in the quantities, shapes and sizes required for all kinds of construction projects.
- Rebar is fast and easy to position ready for concrete pouring. Using reinforcement mesh can speed up the process further, allowing slabs of significant size to be created quickly and consistently.
Getting It Right With Rebar
As with any building material or process, rebar is only a good solution if it is used correctly. There are many different types and grades of rebar, and care must be taken to select the correct type for each construction project. For example, in projects where exposure to moisture and salt are likely, steel rebar could corrode if it is not protected adequately. In extreme cases, epoxy-coated rebar may be used to protect the steel from corrosion.
It’s also important to plan all reinforcement carefully, making sure that the correct rebar shapes are used at each point. There are a number of British Standards that apply to rebar, with rebar shape codes making it easy to identify each type.
In order to avoid wastage and minimise costs and delays, it’s key that the right amount of rebar or reinforcement mesh is purchased – fortunately, there are handy online calculators available, including our own rebar weight calculator.
Online Rebar Weight Calculator
Rebar Use Today
Whilst deformed steel bar is probably the most common form of rebar in use today, there are a number of other types of rebar that have been developed over the years for particular applications. These include carbon steel rebar (sometimes called black bar), European rebar, galvanised rebar and more. As we have already mentioned, problems with corrosion have been addressed in recent years by coating steel rebar with a specialised epoxy. GFRP is a more contemporary development and is made from a glass fibre reinforced polymer. This kind of rebar is much more specialised and therefore more expensive than more traditional rebars, and is really only used when other rebars are not suitable.
Alongside developments in rebar itself, there have been a number of new construction methodologies introduced over the years, to accommodate building styles, site conditions, environmental forces and other factors. Complex slab construction types have evolved, for example for cell-based buildings such as prisons or student accommodation, and in areas of the world where extreme weather events are common, building technology has evolved to create structures that can withstand the harshest of conditions, tolerating very high tensile forces such as hurricanes and floods.
The Future of Rebar
With rebar being used in almost every major construction project for the last 150 years, it’s hard to imagine a world where rebar doesn’t play an integral role in construction. However, new developments in building technology are happening at an incredible pace, and the building methods and materials that we are so familiar with may one day be replaced by smarter options. Demands on sustainability, performance and cost are driving innovation in construction, and new reinforcement products are rapidly gaining traction. One new idea is laser cut sheet steel rebar, which can be cut to precise and very complex shapes, optimising the reinforcement stage of construction and potentially reducing the amount of steel needed by up to 60% when compared with traditional steel rebar.
One new idea is laser cut sheet steel rebar, which can be cut to precise and very complex shapes, optimising the reinforcement stage of construction and potentially reducing the amount of steel needed by up to 60% when compared with traditional steel rebar.
Over in Germany, a revolutionary new reinforcement technique is being used to create a 2-storey, 2200 sq. ft. building on the university campus at Dresden. Carbonhaus, as it is known, has been built entirely without traditional steel reinforcement. Instead, it uses carbon fibre reinforced concrete to provide the same levels of tensile strength as provided by traditional steel rebar use. It’s claimed that carbon fibre reinforced concrete is significantly more environmentally-friendly than steel reinforced concrete, with a similar price.
Undoubtedly, we will continue to see further rapid innovation in construction processes and materials, as we strive towards a sustainable, carbon-neutral global society.
It might be the most instantly recognisable item on a construction site, but rebar plays a vital role in the building industry, and looks set to do so for a long time to come. The global Covid-19 pandemic has put supply pressures on firms around the world, and steel prices remain highly volatile and subject to a variety of market forces. As COP26 spells out the future for all of us, it’s inevitable that there will be big changes ahead for both the steel industry and the construction industry, bringing both challenges and exciting possibilities. For now, rebar remains a central component of almost every construction project, and it will undoubtedly evolve over time to maintain its pivotal role.