Developing concrete ideas with steel
Winner of the European Inventor Award 2011 in the category Industry
Belgian inventor Ann Lambrechts' invention of mixing steel wire elements into concrete has not only improved the stability of structures where it is used, it has reduced building costs and opened up entirely new architectural possibilities.
Inventor: Ann Lambrechts, Belgium
Invention: Steel wire element to improve strength and stability of reinforced concrete
Sector: Civil engineering
Company: N.V. Bekaert S.A.
Today's construction industry features increasingly groundbreaking and innovative architecture. Over the past few decades design has advanced, and new challenges have emerged concerning the utility and cost-effectiveness of building materials.
The strength of concrete proved to be one such challenge. Concrete's tensile strength ensures the soundness of a building by giving the structure stability. Traditionally, reinforcing bars or rebars have been used to improve concrete's strength.
Unfortunately, older rebar solutions are costly and their bulky design limits the architectural possibilities for construction projects. Rebars are often shaped like grids or cages, which can only be incorporated in more traditionally-styled structures. Recent inventive design ideas surpass the rebars' practical capabilities, limiting innovation. This all changed with Ann Lambrechts' introduction of her steel wire element in 2000.
Lambrechts' steel element has opened up a world of new architectural possibilities by improving the bending strength of reinforced concrete structures. Her invention increases the bending tensile strength of concrete by 32%, enabling more pioneering projects to be built.
Besides cost concerns, the steel wire element's revolutionary design significantly increases the overall strength of concrete. The steel wire includes flattened, hook-shaped ends that produce improved anchorage of the steel wire to the concrete, resulting in a more stable structure.
Unlike its predecessors, Lambrechts' solution is also cost-effective. Older solutions drove costs up by requiring rebars to be added to the concrete in sizeable amounts. At only 55 mm in length, Lambrechts' steel wire element is mixed with wet concrete at an impressive proportion of 20 kg to every 50 kg per cubic metre. Fewer steel fibres are needed, without sacrificing stability.
Notably, Lambrechts' steel wire elements have been used in the construction of China's Central Television's (CCTV) headquarters in Beijing. The structure consists of a continuous loop of horizontal and vertical sections. This visionary architecture style was only possible due to improved tensile strength provided by Lambrechts' steel wires.
The steel wire elements are commonly used in an assortment of construction projects. Residential buildings, industrial floors, tunnels, corporate and public buildings all utilize Lambrechts' invention. Each year Dramix steel elements reinforce more than 5 million m³ concrete.
The steel wire element is produced and distributed by the Belgian corporation Bekaert, under the name Dramix®. Bekaert has 28 000 employees worldwide and reached an annual combined sales figure of €4.5 billion in 2010.