Calcined clay (calcined clay production)

Emissions generated by the activity within the product supply chain as described in ecoinvent v3.10. The product "calcined clay" represents a pozzolanic material used in cement production. Calcined clay is produced by grinding and heating of natural clay between 500°C and 900°C. This thermal treatment (activation) converts crystalline clay materials to amorphous alumino silicates. When added to cement amorphous silica reacts with calcium hydroxide formed during calcium silicate hydration from cement forming C-S-H (hydrated calcium silicate). Secondary reactions may occur due to the reactive alumina content of calcined clay forming also C-A-H (hydrated calcium aluminate). The addition of calcined clay to cement result in higher sulphate-resistance of the hydrated paste and in low permeability of the cementitious matrix thus increasing the durability of cementitious products. The cut-off classification is allocatable product. The activity type is ordinary transforming activity. The reference product amount is 1.