Concrete versus Steel

Most buildings that are made, are structurally made from steel. Why would an architect or designer choose one material over the other? Concrete buildings offer many safety advantages over steel skeleton structures. Compared to steel, concrete can endure very high temperatures for long periods and offers excellent protection from explosions. (Burj Khalifa, Dubai – 330,000 cubic meters of concrete used) Building with concrete is also very fast. When time means money this makes it a particularly attractive option. Unlike steel, it is also possible for large sections to be pre-fabricated off site. This again speeds up construction meaning less time developing and more time using the structure. Companies also offer concrete repairs which tend to be a lot quicker, simpler and cheaper than other repairs on steel structures. Steel on the other hand, in terms of cost, is generally a cheaper option. However, the price of steel can fluctuate a lot more than concrete and it is also generally accepted that the cost of insuring a steel building is higher because of the differences in safety. Steel offers architects a far greater array of options when it comes to building design. The strength to weight ratio of steel is higher than any other (affordable) construction material. Steel offers aesthetics that concrete may never be able to. There are positives and negatives to both concrete and steel. But why choose one over another? With two materials offering such diverse positives then it would be wrong to apply them together, right? Wrong. Reinforcing concrete with steel has major benefits. Reinforced concrete with steel is by far, a lot better than either concrete or steel separately. Concrete on its own has one major downfall and that is that it is extremely strong in compression but has little to no strength when there is tension. Rebar is used within concrete to give it the ability to carry tensile loads on a structure. To keep protecting the environment, reinforcing steel is now commonly used. In the UK rebar is 100% recycled scrap steel and at the end of its life steel can be recovered, recycled and used again. Although some concrete buildings may not look great, who’s to say that in the future decorative coatings and innovative designs cannot lead the way in construction? So for safety and cost effectiveness over the long term, concrete reigns supreme despite the need for on-going maintenance and repair. This is of course why it is the natural choice of many of the buildings that we work on where safety is paramount.