In response to Charles Allen's letter (NCE 5 October), I reiterate that concrete provides a very positive contribution to sustainable development. The operational and environmental benets achieved by the material far outweigh the embodied energy impact of its production.
Embodied energy impacts should not, of course, be ignored and continue to be addressed by the cement and concrete industry.
Direct O 2 emissions from Portland cement manufacture have been reduced by 24% between 1990 and 2004 through the use of new technology, the introduction of new efficient manufacturing plants and the closure of older less efcient facilities.
The use of alternative raw materials and fuels has assisted in the improvement of overall environmental performance with a 23% reduction in the use of fossil fuels since 1998.
For historical and technical reasons the UK industry has for many years added both ground granulated blast-furnace slag and pulverised fuel ash to reduce Portland cement content.
Also the use of admixtures to reduce cement content is now almost universal since BS 8500, to the extent that the minimum cement content rarely controls concrete mix design.
What Allen is asking for has been established practice within our industry for some time. His letter only shows that we need to promote our environmental achievements to a wider audience.
Alan Bromage, head of civil engineering, The Concrete Centre, Riverside House, 4 Meadows Business Park, Camberley, Surrey, GU17 9AB