October 2015: CONSTRUCT, the association for specialist concrete contractors, has presented UnPS with an innovation award for design, process and concrete construction. This recognises an innovative tunnel lining system UnPS developed.
The system, known as SmartShell, is a steel fibre reinforced concrete which was applied as a secondary lining to the Lee Tunnel project in London. The tunnel will be subject to large forces, such as water surges, so the secondary lining had to be heavily reinforced. UnPS identified that challenging the traditional design and construction methodology of the secondary lining would make significant improvements to the delivery of the project, and performance of the finished tunnel.
Rigorous testing of the steel fibre impregnated concrete showed that any cracks appearing were small enough to self-heal. In addition to providing economical and efficient structural reinforcement, the scattered distribution of the steel fibres greatly improves corrosion resistance.
By casting the lining without steel rebar, the risks associated with steel bar fixing were eliminated which resulted in a simpler and safer construction methodology. The SmartShell system has brought a multitude of design, cost and efficiency benefits, including the elimination of 15,000 tonnes of steel rebar, £13.5 million saved on material costs, and a significant saving on construction time.
Professor Colin Eddie, Managing Director of UnPS, said: “We have designed and implemented a system which has redefined the way projects such as these are constructed. The SmartShell system has added an incredible amount of value to the Lee Tunnel project and we’re delighted to have been recognised by the wider industry.”