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US 2012/0055376 A1Published application
Portland limestone calcined clay cement
AssigneeAalborg Portland A/S
InventorsDuncan Herfort, Jesper Sand Damtoft
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AssigneeAalborg Portland A/S
InventorsDuncan Herfort, Jesper Sand Damtoft
Estimating the term…
The claimed subject matter relates to a novel cement comprising Portland cement clinker and a supplementary cementitious material. The supplementary cementitious material comprises a heat treated clay material and an optionally heat treated carbonate material, wherein the clay material has been heat treated optionally together with the carbonate material in such a way that the heat treated clay material is substantially dehydroxylated while the optionally heat treated carbonate material remains substantially carbonated. This can be achieved by premixing the carbonate and clay materials before heat treating to 400-700 C, or heat treating the clay material separately to a temperature of up to 900 C. When used in the final application the cement results in much higher strengths than would be predict from any other combination of these materials.
-29. (canceled)
A cement comprising Portland cement clinker and a supplementary cementitious material, characterised in that the supplementary cementitious material comprises a) a calcined clay produced at a temperature of between 500° C. and 900° C. and b) a carbonate material selected among the group comprising limestone, magnesium carbonate, calcium magnesium carbonate, or mixtures thereof, wherein the carbonate material has been ground to a specific surface area of 3000-15000 cm2/g determined using the Blaine method described in EN 196, and wherein only the clay material has been heat treated, and wherein the weight ratio of calcined clay material to carbonate material is between 0.25 and 3.
A method of producing a cement comprising Portland cement clinker and a supplementary cementitious material comprising the steps of a) providing a carbonate material selected among the group comprising limestone, magnesium carbonate, calcium magnesium carbonate, or mixtures thereof, said carbonate material being ground to a specific surface area of 3000-15000 cm2/g determined using the Blaine method described in EN 196 and a clay material, b) heating the clay material separately at a temperature of between 500° C. and 900° C., c) mixing the heat treated clay material with the limestone material in a weight ratio of heat treated clay material to limestone material of between 0.25 and 3, and d) blending the mixture of c) with a Portland cement clinker.
Dependencies are inferred from the claim text.