ABSTRACT
This chapter discusses some alternatives to Portland cement. Calcium aluminate cement (CAC) is, as can be deduced from the name, based on calcium aluminate rather than the calcium silicate of Portland cement. The manufacture of CAC has some parallels with that of Portland cement. The setting time of CAC is about 30 minutes longer than that of a typical Portland cement. Hardened cement that has been formed at low temperatures will therefore become more porous as its hydrates convert, with a consequent loss of strength. Despite this CAC was omitted from the list of cements permitted in design standards for reinforced and pre-stressed concrete, and so it was effectively banned from use for this purpose in the UK and in many other countries. The search for uses of industrial waste as an alternative to sending it to landfill has resulted in the development of some potential processes for conversion to cementitious materials.
