'Green' Cement?

We have already noted that the heating of limestone to create cement is a very major (about 5% of the world's annual production) source of the 'greenhouse gas', carbon dioxide and, even in this difficult economic times, human love to build. Reports have been made of the development of 'Novacem', a new Magnesium silicates-based cement by Dr Vlasopoulos and his team at Imperial College, London (http://www.guardian.co.uk/environment/2008/dec/31/cement-carbon-emissions). The new material is said to be carbon neutral, as it requires much less heating than limestone and actually absorbs carbon dioxide when it hardens. There is considerable commercial and environmental interest in the material but much will depend on price and people possibly finding it easier to source cement from relatively abundant limestone (companies have often paid for the mining rights in advance). Nevertheless, this is an interesting development, which might well improve the construction industry's carbon footprint.