High early strength pozzolan cement blends

• US 8,323,399 B2
• Filed: 07/01/2011
• Issued: 12/04/2012
• Est. Priority Date: 10/10/2008
• Status: Active Grant

• Current Assignee: Roman Cement, LLC
• Original Assignee: Roman Cement, LLC
• Inventors: Guynn, John M., Hansen, Andrew S.
• Primary Examiner(s): MARCANTONI, PAUL D
• Application Number:
  US13/175,636
• Publication Number:
  US 20110259246A1
• Time in Patent Office: 522 Days
• Field of Search: 106/705, 106/713, 106/789
• US Class Current: 106/705
• CPC Class Codes: C04B 14/14 Minerals of vulcanic origin granite C04B14/048
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 20/0076 characterised by the grain distribution
• CPC Class Codes: C04B 20/008 Micro- or nanosized fillers, e.g. micronised fillers with particle size smaller than that of the hydraulic binder colloidal silica C04B14/062 ; silica fume C04B18/146
• CPC Class Codes: C04B 2103/0088 Compounds chosen for their latent hydraulic characteristics, e.g. pozzuolanes
• CPC Class Codes: C04B 2103/10 Accelerators; Activators
• CPC Class Codes: C04B 2103/20 Retarders
• CPC Class Codes: C04B 2103/302 Water reducers
• CPC Class Codes: C04B 2103/44 Thickening, gelling or viscosity increasing agents
• CPC Class Codes: C04B 22/064 of the alkaline-earth metals
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 28/18 containing mixtures of the silica-lime type
• CPC Class Codes: C04B 7/02 Portland cement
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10S 106/01 Fly ash

Abstract

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.

Claims

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; and

a 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 μ

m.

7. A blended cement composition as in claim 1, wherein the hydraulic cement fraction has a D₉₀ less than about 20 μ

m.

8. A blended cement composition as in claim 1, wherein the pozzolan fraction has a D₁₀ greater than about 10 μ

m.

9. A blended cement composition as in claim 1, wherein the pozzolan fraction has a D₁₀ greater than about 15 μ

m.

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.

18. A blended cement composition as in claim 1, wherein the pozzolan fraction has a D₁₀ greater than about 20 μ

m.

11. A blended cement composition comprising:

a hydraulic cement fraction comprised of differently sized hydraulic cement particles having a D₈₅ less than about 20 μ

m 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; and

a 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 μ

m 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 μ

m;

obtaining ground granulated blast-furnace slag particles having a D₈₅ less than about 20 μ

m;

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 μ

m and a fineness that is less than a fineness of combined Portland cement particles and ground granulated blast-furnace slag particles; and

combining 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 μ

m.

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 μ

m.

19. A blended cement composition as in claim 11, wherein the pozzolan fraction has a D₁₀ greater than about 20 μ

m.

20. A blended cement composition comprising:

a hydraulic cement fraction comprised of differently sized hydraulic cement particles having a D₈₅ less than about 20 μ

m 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; and

a 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 μ

m 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.