Buildings and infrastructure

Construction is one of the most important steel-using industries, accounting for more than 50% of world steel production. Buildings - from houses to car-parks to schools and skyscrapers - rely on steel for their strength. Steel is also used on roofs and as cladding for exterior walls.

According to the UN's latest forecast dating July 2015, world population will reach 8.5 billion in 2030 and 9.7 billion in 20501..This will be accompanied by rapid urbanisation. As the need for buildings and infrastructure continues to grow worldwide, reducing consumption of natural resources and associated emissions is crucial for future sustainability.

Steelmakers around the world are increasingly providing construction solutions that enable energy-efficient and low-carbon-neutral buildings. These solutions reduce the environmental impact over the structures’ life cycle and help to extend their life span through design for disassembly and reuse.

Steel can provide the solutions to infrastructure and construction needs in developing countries and in climate resilient cities through enabling protective coastal and wind-resistant designs. While buildings currently account for about 20% of global greenhouse gas emissions, they also present many opportunities for reducing emissions and mitigating climate change.2,3

Not only is steel affordable, readily available and safer, its intrinsic properties, such as strength, versatility, durability and 100% recyclability allow for improved environmental performance across the entire life cycle of buildings. 

The advanced high-strength steels used in steel-plate applications also find uses in a number of related industries. Offshore oil rigs, bridges, civil engineering and construction machines, rail carriages, tanks and pressure vessels, nuclear, thermal and hydroelectric plants – all these applications benefit from the attributes of modern steels.

How steel is used in buildings and infrastructure

The possibilities for using steel in buildings and infrastructure are limitless. The most common applications are listed below4.

For buildings

• Structural sections: these provide a strong, stiff frame for the building and make up 25% of the steel use in buildings.
• Reinforcing bars: these add tensile strength and stiffness to concrete and make up 44% of steel use in buildings. Steel is used because it binds well to concrete, has a similar thermal expansion coefficient and is strong and relatively cost-effective. Reinforced concrete is also used to provide deep foundations and basements and is currently the world’s primary building material.
• Sheet products: 31% is in sheet products such as roofing, purlins, internal walls, ceilings, cladding, and insulating panels for exterior walls.
• Non-structural steel: steel is also found in many non-structural applications in buildings, such as heating and cooling equipment and interior ducting.
• Internal fixtures and fittings such as rails, shelving and stairs are also made of steel. 

For infrastructure

• Transport networks: steel is required for bridges, tunnels, rail track and in constructing buildings such as fueling stations, train stations, ports and airports. About 60% of steel use in this application is as rebar and the rest is sections, plates and rail track.
• Utilities (fuel, water, power): over 50% of the steel used for this application is in underground pipelines to distribute water to and from housing, and to distribute gas. The rest is mainly rebar for power stations and pumping houses.

Footnotes:

1 World Population Prospects The 2015 Revision United Nations, World Population Prospects, The 2015 Revision, p. 2, issued, 29 July 2015
2 IPCC Fourth Assessment Report, Working Group III, ch 1.
3 Metz, B., Controlling Climate Change, 2010, Cambridge University Press.
4 Allwood J.M., Cullen J.M., et al., 2012, Sustainable Materials: With both eyes open, p. 31-38. UIT Cambridge, England.