Reporter 402, 19 May 1997

The long road to perfection

All over the world a dream is being striven towards – the perfect road surface that will last indefinitely without repair. The realisation of this dream could affect all our lives. The perfect road is some time away, but, as science develops, major problems are being eradicated one by one. Important advances were discussed at the 2nd European Symposium on the Performance and Durability of Bituminous Materials hosted by the Civil Engineering Materials Unit at Weetwood Hall and chaired by Professor Joe Cabrera last month.

Extreme climates pose a major challenge to researchers, but collaborative work between the Unit and the Universiti Sains Malaysia has developed a porous asphalt – eliminating the problem of water lying on roads and providing a major benefit to countries prone to frequent heavy rain.

Cracked and deformed roads are a common sight in other countries, so the development of 'dense bituminous mixes' which can withstand high temperatures by the Unit and Al-Fateh University in Libya will be crucial in cutting maintenance and repair costs.

Road building is often associated with environmental damage, but another innovation involves recycling materials and reducing the need for quarrying. Waste from demolition, which costs nearly £3 per tonne to dump, can now be recycled and used in roads – without sacrificing quality. As well as helping the environment costs are reduced – an advantage to everyone from local authorities in this country to infrastructure planners in developing countries.

The process of actually laying down a road surface consumes huge amounts of energy. The materials used in black tops must be heated to 160° and 28m tonnes are used in the UK every year. Research at the Leeds unit has resulted in a 'low energy mix' which only has to be heated to 120° and can be laid down at 80°C resulting in significant energy savings.

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