David Ball, new chair of bridge group campaigns for re-evaluation

The role of concrete in sustainable structures is underestimated according to David Ball, who has been appointed Chairman of the Concrete Bridge Development Group (CBDG). He argues that Britain is missing the opportunity to build iconic landmark structures because of outdated views of concrete.

“Our understanding of concrete’s properties has increased over recent years and this has enabled us to increase its strength and durability. One of the major problems associated with the concrete structures of the 1970s was that water penetrated the structures, corroding the steel reinforcements and loosening facades. These issues have now been addressed and we have a new generation of concrete that across its lifetime is more environmentally acceptable than steel or composites structures.”

David is a materials engineer and chairman of The David Ball Group. He has been involved in many large international projects such as Chek Lap Kok airport in Hong Kong and ‘the great manmade river project’ in Libya, and believes that the potential of concrete is underestimated in the UK. He continues:

“Many of the landmark structures built across the world in recent times – such as the Burj Al Arab Hotel in Dubai – are made from concrete. It is a material that offers considerable scope for exciting and memorable structures.

“Bridges have always been culturally defining structures and I believe that one role of the CBDG is to communicate the benefits of improved concrete technology to government. Bridge projects should not just improve the infrastructure but also seek to create iconic structures that enhance the landscape of major towns and cities.”

David Ball’s comments come at a time when one of the wettest years in history is creating considerable pressure on the built environment.

“Rising groundwater levels will inevitably increase water pressure on concrete bridges. But technology now exists to provide better waterproofing and this will improve frost protection and corrosion resistance,” he explains.

“Even a small increase in average temperatures will lead to high peak temperatures in the summer causing structures to expand, so this needs to be considered within the design of the concrete. Additionally, careful detailing on the sub-structures will minimise water permeability and capillary rise.”

The Concrete Bridge Development Group was established in 1991 to promote best practice. It has over 100 members drawn from construction companies, consultants and industry bodies.

There are some 100,000 existing concrete structures in the UK alone. The earliest example of a mass concrete bridge was on the District Line designed by Thomas Marr Johnson and built c.1865. It was not until the first decade of the 20th Century that reinforcement, as we know it today, was introduced. This was due almost entirely to L.G. Mouchel. The first was an 18ft span bridge at Chewton Glen in Hampshire in 1902, followed two years later by a 40ft span beam and slab bridge at Sutton Drain in Hull.

David Ball hopes that the UK will continue to innovate with concrete:

“Research is continuing to improve the durability and strength of concrete. Already we are seeing how this can reduce the proportion of concrete required within the mix, reducing both cost and improving sustainability. I think that CBDG has a vital role in driving this research and disseminating the results.”

Email: rachel@holdsworth-associates.co.uk