May I take the opportunity to reassure Charles Allen (NCE 5 October) that the broader concrete industry is indeed already doing much to reduce the CO 2 emissions associated with the use of Portland cement in concrete.
His suggestions of using admixtures, mix design and 'cement replacement technology' (sic) are wise and, I am pleased to report, already widespread and effective.
Nevertheless, that is not to say there is no scope for improvement.
Bryan Marsh (M), president, Institute of Concrete Technology, bryan. marsh@arup. com