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Natural pozzolana and natural calcined pozzolana

Reduction in the embodied carbon of concrete by reducing the Portland cement content can be achieved by partial replacements. Fly ash, GGBS and limestone powder are well established in the market and their proportions to achieve durability are tabulated in BS 8500.

The 2019 version of BS 8500 additionally allows for the use of natural pozzolana, although the commercial availability of such products is still to be established in quantity. These materials are covered in;

BS 8615: 2019 Specification for pozzolanic materials for use with Portland cement:
Part 1 Natural pozzolana and natural calcined pozzolana
Part 2 High reactivity natural calcined pozzolana

This British Standard specifies requirements for the production, chemical composition, mechanical and physical properties of pozzolanic materials for use in combination with Portland cement class 42,5 N or greater, conforming to BS EN 197-1:2011, as a component of concrete, mortar or grout. It also specifies requirements for marking, provision of information and conformity criteria for the manufacture’s autocontrol system.

Part 1 covers a) natural pozzolana as defined in BS EN 197-1:2011,; and b) natural calcined pozzolana, as defined in BS EN 197-1:2011, Part 2 covers high reactivity natural calcined pozzolana.

Acknowledgement: The Concrete Society