Cementing A Reputation For Innovation

Cementing a reputation for innovation

By Lisa Urquhart, Financial Times

August 19 2004

Mention aggregates and most people's eyes glaze over. It is a subject that many feel is about as interesting as watching concrete harden.

But environmental and technical challenges have forced RMC, the UK's largest aggregates group, to come up with a range of interesting and innovative solutions for different strands of its business.

A new manufacturing process at the group's cement plant in Rugby has secured RMC a European Award for the Environment for its work in reducing sulphur dioxide emissions.

For the uninitiated, cement is made from cooking limestone, clay, sand and iron oxide at very high temperatures in specially constructed kilns. An unwanted byproduct of cement production is sulphur dioxide, the chief cause of acid rain.

Bob Millard, manager at the plant, which is part of RMC's Rugby Cement division, says concern about emissions prompted a decision to rebuild the plant. This led RMC to experiment with the design of cement kilns with interesting results.

"We found that adding clay, which contains the sulphur, at a different stage of the production process causes the lime to act as a desulphuring agent, dramatically cutting emissions." With the new technique, sulphur dioxide emissions are now 50mg per cu metre of gas, compared with 200mg for the previously most efficient kilns.

Unsurprisingly, the process has generated interest from other cement companies in Europe, and not only for its emission reduction but because of other benefits as well, Mr Millard says. He explains: "The sulphur goes into the cement instead and the increased sulphur helps the performance of the concrete. "Traditional kilns also produce gypsum, which has to be disposed of. The beauty of this process is that there is no byproduct, no requirement for additional energy and no additional cost."

But it's not just environmental concerns that have forced novel solutions. Moving from cement to concrete, this year the group ran into difficulties in fulfilling its biggest ever contract to supply 2.4m cu metres of runway for the airport extension in Dubai. Temperatures in Dubai average 30°C, rising to 50°C in the summer.

Graeme Clack of RMC said: "Two of the three ingredients of ready mixed concrete - aggregates and cement - are inevitably warmed by the sun as they are stored on site or trucked in." However, the ideal temperature range for concrete mix is 22°C to 25°C, meaning that not only would the concrete dry too quickly in the desert temperatures but it would fail to achieve the required strength needed for a runway. RMC solved this conundrum by bringing a bit of the Arctic to the desert. The group constructed several ice-making plants that produced more than 650 tonnes of flaked ice and iced water. Adding this icy slush to the concrete mix ensured that it dried at a suitable temperature, allowing work to continue. Closer to home, the group is also helping to solve a recycling problem.

White and brown glass, used to bottle soft drinks, spirits and beer, can easily be recycled for the same purposes. Green glass, however, finds it slightly harder to achieve an afterlife and often ends up in landfill sites. This is mainly because one of the chief uses of green glass is bottling wine, and - much as English wine advocates like to trumpet the quality of the home tipple - home-produced volumes come nowhere near those imported from France, Australia or Spain. To help address the issue of 1m tonnes of excess glass in the UK, RMC is asking motorists to drive over it. Fortunately, most drivers will be blissfully unaware of this as the group has turned it into "Glassphalt".

Glassphalt is made up of one-third glass combined with limestone and bitumen and has this year been used in repairs of parts of the M50 and M6 motorways, replacing the normal layer of aggregate below the road surface.

So for those who think aggregates are uninteresting, it might be "time to think again" says Rob Gaimster, national technical manager of RMC materials. But, as president of the institute of concrete technology, he might be just a little biased.