Nerves of steel
Developers are careful about sourcing the right steel. The grade has to be just right to be used in high-rises
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. With increasing urbanisation matching that of an increasing population, there’s a need for buildings and infrastructure. This will continue to grow worldwide, reducing consumption of natural resources and associated emissions is crucial for future sustainability.
One of the ways of reducing carbon footprint is through the use of steel. 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.
Whether you are building a factory, an airplane hangar, a soccer field, a church or anything else imaginable, steel buildings are versatile and customisable. But developers need to be careful when sourcing steel for buildings, especially high-rises. Mahesh Khaitan, director, Salarpuria Sattva Group, says, “While steel can be a volatile commodity, it is one of the most important materials used in the building. It possesses properties that include durability, versatility and strength making.
He lists out some parameters that need to be considered when buying steel:
• Check for identification marks on it from the manufacturing company. Usage of a popular brand of steel ensures a certain quality. It is advisable to use a government-approved brand or ISI brand
• Ensure that the steel is rust free
• It is necessary to ask for chemical composition test from the supplier. Apart from other material, the content of carbon is very important and it should not be more that 0.25% as it would accelerate corrosion which in turn will not only reduce the life of building but also will increase frequent repairing work
• When buying readymade cut bars, the shape and length of each type of bar as per bar bending schedule have to be checked
• While buying steel bars, one must read all the technical specifications described in the product literature.
Srikanth Srinivasan, president, procurement, Puravankara, says, “Steel is a big cost driver for us and considering that most of our developments are high-rises, we buy plenty of steel. Most of its is routed directly or indirectly through contractors. Prices are negotiated on a monthly basis.
Puravankara has adopted the practice of ordering on a monthly basis as it means getting the best price. With variety of steel available in the market, the company is careful to look at both primary and secondary manufacturers of steel.
With inferior quality of goods doing the rounds in markets, developers scan the IS code of steel (also other goods) before making a purchase.
Murtuza Lakdawala, head, construction & design, Goodwill Developers, says, “Steel is essential in construction today. Buildings that have inherently used steel are resistant to natural and man-made wear. They have the ability to withstand termites, fire, rust and rot. You can be confident your building will stand strong through a wide range of calamities. Steel buildings are so tough that their ductile and flexible nature lead them to be a popular choice when building in earthquake prone regions.”
Ashok Mohanani, chairman, Ekta World, says, “Considering that everyone is now talking about green buildings, the motive of this concept involves planning, design, construction, and operations of buildings/projects, foremost considerations like energy use, water use, indoor environmental quality, material section and the building’s effect on the society and its surroundings. Consideration of sustainability features in all phases of designing and planning the procedure of the project, followed by construction and production of building materials, and one of them is steel.
He adds that utilisation of safe and environmentally friendly building materials and products and systems that are easily accessible to preserve and service well must be looked at carefully.
Srinivasan also adds that steel buildings can be built with large, wide-open interiors without the obstructions created by columns. This means one can have the floor plan one wants without any interruptions.
Lakdawala says that steel’s lighter weight relative to other framing materials helps in creating a smaller, simpler foundation. These efficiencies in execution translate to considerable resource efficiencies and economic benefits, including accelerated project schedules, reduced site management costs and an earlier return on investment.
When a steel-framed building is demolished, its components can be reused or circulated into the steel industry’s closed-loop recycling system for melt down and repurposing. Steel can be recycled endlessly without loss of properties. Nothing is wasted. Steel saves on the use of natural raw resources since around 30% of today’s new steel is already being made from recycled steel.
Steel is generally a one-time purchase, and it has a long lasting service life when embedded in concrete. Khaitan says, “If we leave it in open environment, they get stained fast. Hence it is advisable to use it as early as possible. It should not be stacked directly on the ground, as the ground moisture will rust it.
Steel should be stored in a warehouse and a wooden plank is placed below so it should not directly rest on ground. It is also advisable to try to learn how to test the materials on site in case of bulk buying. The quality of steel will result in breaking or developing cracks on the surface if they are not standardised.”
Steel plates used in construction are low-carbon steel which facilitates ease of construction as holes can be drilled on these plates and they can also be formed to suit specific requirements. Steel plates required by small residences are different from the ones required by multi-storied buildings, airports, and sports arenas. Steel plates are manufactured in various sizes and thickness.
Plain Carbon Steel or mild steel is the most common type of steel used in building construction. Known for its immeasurable strength and durability, mild steel is extremely useful in buildings and is proven to have great benefits. It is not only immensely flexible but also elastic and has great plasticity. It can also withstand earthquakes without causing cracks in the steel.