Life cycle benefits of calcium silicate replacements

Abstract

The most universal of all binders, produced in huge quantities worldwide, is Portland cement. Following introduction in 1824 by Joseph Aspin, it has quite properly enjoyed popular appeal with craftsmen, architects and engineers for its bonding properties. The manufacture of cement relies largely on primary minerals for feedstock and depends heavily on carboniferous fuels for production. Naturally occurring minerals have similar properties as a binder and have been used in their own right or as partial replacements for cement. Likewise, secondary products recovered from modern manufacturing or energy production processes also have the potential to replace in part a proportion of cement. Life cycle analysis of cement production supports the proposition that large quantities of fossil fuel and primary minerals are being unnecessarily used in situations where alternative replacements are available and frequently placed to waste. This paper considers the implications of cement production on a sustainable environment. It argues that, contrary to some opinions, partial replacement of cement with secondary wastes which have potential cementitious properties can enhance and improve structures which otherwise would include only Portland cement as the binder. Acceptance of this argument would leave massive quantities of primary minerals untouched and reduce the amount of fossil fuels demanded of cement production on the present scale.