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Alkali activated cements (including geopolymer cements)

Alkali-activated cements gain their strength, and other properties, via chemical reaction between a source of alkali (soluble base activator) and aluminate-rich materials.

The aluminate-containing material - the pozzolan/latent hydraulic binder component of the cement - can be coal fly ash, municipal solid waste incinerator ash (MSWIA), metakaolin, blastfurnace slag, steel slag or other slags, or other alumina-rich materials.

The alkali used as the activator tends to be an alkali silicate solution such as sodium silicate (waterglass) but can also be sodium hydroxide solution, or a combination of the two, or other source of alkali (such as lime).

Geopolymeric cements are particular examples of ´alkali-activated pozzolanic cements´ or ´alkali-activated latent hydraulic cements´.

All alkali-activated cements tend to have lower embodied energy/carbon footprints than Portland cements (up to 80-90% but this is pozzolan dependent).

Manufacture on a commercial basis is underway in the UK, Australia, USA and possibly, China.

Covered by PAS 8820:2016 Construction materials. Alkali activated cementitious material and concrete. Specification

For more information, see: Novel cements low energy low carbon cements

Acknowledgement: The Concrete Society