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A high early strength blended cement composition includes larger sized fly ash and/or natural pozzolan particles blended with smaller sized hydraulic cement particles containing tricalcium silicate and/or dicalcium silicate (e.g., Portland cement and/or ground granulated blast furnace slag). Excess

A high early strength blended cement composition includes larger sized fly ash and/or natural pozzolan particles blended with smaller sized hydraulic cement particles containing tricalcium silicate and/or dicalcium silicate (e.g., Portland cement and/or ground granulated blast furnace slag). Excess calcium released from the hydraulic cement particles when mixed with water forms calcium hydroxide available for reaction with the fly ash and/or natural pozzolan. The fineness of the hydraulic cement particles is substantially greater than the fineness of the fly ash and/or natural pozzolan particles (e.g., about 1.25 to about 50 times greater). Reducing or eliminating coarse hydraulic cement particles that cannot fully hydrate but include unreacted cores reduces or eliminates wasted cement normally found in concrete. Replacing some or all of the coarse cement particles with coarse pozzolan particles provides a blended cement composition having significantly lower water demand compared to the hydraulic cement fraction by itself.

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1. A blended cement composition comprising: a hydraulic cement fraction comprised of differently sized hydraulic cement particles, wherein the hydraulic cement fraction, when mixed with water, provides excess calcium hydroxide that is available for reaction with a pozzolan, the hydraulic cement frac

1. A blended cement composition comprising: a hydraulic cement fraction comprised of differently sized hydraulic cement particles, wherein the hydraulic cement fraction, when mixed with water, provides excess calcium hydroxide that is available for reaction with a pozzolan, the hydraulic cement fraction having a Blaine fineness greater than about 500 m2/kg, the hydraulic cement fraction comprising Portland cement and ground granulated blast-furnace slag; anda pozzolan fraction comprised of differently sized pozzolan particles selected from the group consisting of fly ash, ground slag, and/or natural pozzolan that reacts with calcium hydroxide in the presence of water, including calcium hydroxide provided by the hydraulic cement fraction when mixed with water, in order to form solid hydration products having cementitious properties, the pozzolan fraction having a Blaine fineness that is less than the Blaine fineness of the hydraulic cement fraction. 2. A blended cement composition as in claim 1, wherein the Blaine fineness of the hydraulic cement fraction is at least about 1.5 times greater than the Blaine fineness of the pozzolan fraction. 3. A blended cement composition as in claim 1, wherein the Blaine fineness of the hydraulic cement fraction is at least about 2 times greater than the Blaine fineness of the pozzolan fraction. 4. A blended cement composition as in claim 1, wherein the Blaine fineness of the hydraulic cement fraction is greater than about 650 m2/kg. 5. A blended cement composition as in claim 1, wherein the Blaine fineness of the pozzolan fraction is less than about 325 m2/kg. 6. A blended cement composition as in claim 1, wherein the hydraulic cement fraction has a D85 less than about 20 μm. 7. A blended cement composition as in claim 1, wherein the hydraulic cement fraction has a D90 less than about 20 μm. 8. A blended cement composition as in claim 1, wherein the pozzolan fraction has a D10 greater than about 10 μm. 9. A blended cement composition as in claim 1, wherein the pozzolan fraction has a D10 greater than about 15 μm. 10. A blended cement composition as in claim 1, wherein the hydraulic cement fraction and pozzolan fraction form a dry blend of particles with no added water. 11. A blended cement composition comprising: a hydraulic cement fraction comprised of differently sized hydraulic cement particles having a D85 less than about 20 μm and a first specific surface area, wherein the hydraulic cement fraction, when mixed with water, provides excess calcium hydroxide that is available for reaction with a pozzolan, the hydraulic cement fraction comprising Portland cement and ground granulated blast-furnace slag; anda pozzolan fraction comprised of differently sized pozzolan particles selected from the group consisting of fly ash, ground slag and natural pozzolan, the pozzolan fraction having a D10 greater than about 15 μm and being that reacts with calcium hydroxide in the presence of water, including calcium hydroxide provided by the hydraulic cement fraction when mixed with water, in order to form solid hydration products having cementitious properties, the pozzolan fraction having a second specific surface area that is less than the first specific surface area of the hydraulic cement fraction. 12. A blended cement composition as in claim 11, wherein the hydraulic cement fraction has a Blaine fineness greater than about 500 m2/kg and wherein the Blaine fineness of the Portland cement fraction is about 1.25 times to about 50 times greater than a Blaine fineness of the pozzolan fraction. 13. A blended cement composition as in claim 11, wherein the Blaine fineness of the Portland cement fraction is greater than about 650 m2/kg and wherein the Blaine fineness of the Portland cement fraction is about 1.5 times to about 30 times greater than a Blaine fineness of the pozzolan fraction. 14. A blended cement composition as in claim 11, further comprising water, fine aggregate, coarse aggregate and at least one of inert filler, lime, lye, water reducing admixture, accelerant, retardant, hydration stabilizer, or rheology-modifying agent so as to form fresh concrete. 15. A method of manufacturing a blended cement composition according to claim 11, comprising: obtaining Portland cement particles having a D85 less than about 20 μm;obtaining ground granulated blast-furnace slag particles having a D85 less than about 20 μm;obtaining a pozzolan fraction comprised of differently sized pozzolan particles selected from fly ash, ground slag and/or natural pozzolan, the pozzolan fraction having a D10 greater than about 15 μm and a fineness that is less than a fineness of combined Portland cement particles and ground granulated blast-furnace slag particles; andcombining the hydraulic cement fraction and the pozzolan fraction to yield the blended cement composition. 16. A method as in claim 15, wherein the Portland cement particles and/or the granulated blast-furnace slag particles have a D90 less than about 20 μm. 17. A method as in claim 15, wherein the Portland cement particles and/or the granulated blast-furnace slag particles have a D90 less than about 15 μm. 18. A blended cement composition as in claim 1, wherein the pozzolan fraction has a D10 greater than about 20 μm. 19. A blended cement composition as in claim 11, wherein the pozzolan fraction has a D10 greater than about 20 μm. 20. A blended cement composition comprising: a hydraulic cement fraction comprised of differently sized hydraulic cement particles having a D85 less than about 20 μm and a first specific surface area, wherein the hydraulic cement fraction, when mixed with water, provides excess calcium hydroxide that is available for reaction with a pozzolan, the hydraulic cement fraction comprising Portland cement and a cementitious pozzolan comprising calcium oxide and silica; anda pozzolan fraction comprised of differently sized pozzolan particles selected from the group consisting of fly ash, ground slag and natural pozzolan, the pozzolan fraction having a D10 greater than about 15 μm and that reacts with calcium hydroxide in the presence of water, including calcium hydroxide provided by the hydraulic cement fraction when mixed with water, in order to form solid hydration products having cementitious properties, the pozzolan fraction having a second specific surface area that is less than the first specific surface area of the hydraulic cement fraction.