Particle packed cement-SCM blends

Abstract

Cement-SCM blends employ particle packing principles to increase particle packing density and reduce interstitial spacing between the cement and SCM particles. Particle packing reduces the amount of water required to obtain a cement paste having a desired flow, lowers the water-cementitious material ratio (w/cm), and increases early and long-term strengths. This may be accomplished by providing a hydraulic cement fraction having a narrow PSD and at least one SCM fraction having a mean particle size that differs from the mean particle size of the narrow PSD cement by a multiple of 3.0 or more to yield a cement-SCM blend having a particle packing density of at least 57.0%.

The invention claimed is: 
     
       1. A cement-(SCM) cement-SCM blend comprising:
 a narrow particle size distribution (PSD) hydraulic cement fraction having a PSD characterized by a lower PSD endpoint, median particle size, and upper PSD endpoint; and 
 at least one two supplementary cementitious material (SCM) fractionfractions, each having a PSD characterized by a lower PSD endpoint, median particle size, and upper PSD endpoint that differ from the lower PSD endpoint, median particle size, and upper PSD endpoint of the hydraulic cement fraction, 
 wherein at least one of the SCM fractions has a median particle size that is at least 3 times greater than the median particle size of the hydraulic cement fraction in order for the cement-SCM blend, when initially mixed with water, to form a cement paste having a maximum particle packing density of at least 57.0%. 
 
     
     
       2. A cement-SCM blend as in  claim 1 , wherein the cement-SCM blend forms a cement paste, when initially mixed with water, having a maximum particle packing density of at least 60%. 
     
     
       3. A cement-SCM blend as in  claim 1 , wherein the cement-SCM blend forms a cement paste, when initially mixed with water, having a maximum particle packing density of at least 65%. 
     
     
       4. A cement-SCM blend as in  claim 1 , wherein the cement-SCM blend forms a cement paste, when initially mixed with water, having a maximum particle packing density of at least 70%. 
     
     
       5. A cement-SCM blend as in  claim 1 , wherein the cement-SCM blend comprises a first SCM fraction having a median particle size such that the median particle size of the hydraulic cement fraction is at least 3.0 times the median particle size of the first SCM fraction and a second SCM fraction having a median particle size that is at least 3.0 times the median particle size of the hydraulic cement fraction. 
     
     
       6. A cement-SCM blend as in  claim 5 , wherein the median particle size of the hydraulic cement fraction is at least 3.5 times the median particle size of the first SCM fraction and/or the median particle size of the second SCM fraction is at least 3.5 times the median particle size of the hydraulic cement fraction. 
     
     
       7. A cement-SCM blend as in  claim 5 , wherein the median particle size of the hydraulic cement fraction is at least 4 times the median particle size of the first SCM fraction and/or the median particle size of the second SCM fraction is at least 4 times the median particle size of the hydraulic cement fraction. 
     
     
       8. A cement-SCM blend as in  claim 5 , wherein the median particle size of the hydraulic cement fraction is at least 5 times the median particle size of the first SCM fraction and/or the median particle size of the second SCM fraction is at least 5 times the median particle size of the hydraulic cement fraction. 
     
     
       9. A cement-SCM blend as in  claim 5 , wherein the cement-SCM blend further comprises a third SCM fraction having a median particle size that is at least 3.0 times the median particle size of the second SCM fraction. 
     
     
       10. A cement-SCM blend as in  claim 1 , wherein the hydraulic cement and the at least one SCM fractions are processed and blended without intergrinding. 
     
     
       11. A method of manufacturing a cement-SCM blend as in  claim 1 , the method comprising:
 providing a the narrow particle size distribution (PSD) hydraulic cement; 
 blending the narrow PSD hydraulic cement with the at least one two supplementary cementitious material (SCM) fractions to form the cement-SCM blend. 
 
     
     
       12. A method as in  claim 11 , wherein the narrow PSD hydraulic cement is processed using a high pressure grinding roll in combination with air classification. 
     
     
       13. A method as in  claim 11 , further comprising blending at least one of fine aggregate, coarse aggregate, water, or chemical admixture with the hydraulic cement and at least one SCM. 
     
     
       14. A cementitious composition comprising:
 a narrow particle size distribution (PSD) hydraulic cement fraction having a PSD characterized by a lower PSD endpoint, median particle size, and upper PSD endpoint; 
 at least one two supplementary cementitious material (SCM) fraction fractions, each having a PSD characterized by a lower PSD endpoint, median particle size, and upper PSD endpoint that differ from the lower PSD endpoint, median particle size, and upper PSD endpoint of the hydraulic cement fraction, 
 wherein at least one of the SCM fractions has a median particle size that is at least 3 times greater than the median particle size of the hydraulic cement fraction in order for the hydraulic cement fraction and the at least one SCM fraction, when initially mixed with water, to form a cement paste having a maximum particle packing density of at least 57.0%; and 
 at least one of fine aggregate, coarse aggregate, water, or chemical admixture. 
 
     
     
       15. A cementitious composition as in  claim 14 , wherein the cementitious composition comprises freshly mixed or hardened concrete. 
     
     
       16. A cement-SCM blend as in  claim 5 , wherein:
 the narrow PSD hydraulic cement fraction has a d90 in a range of 11 μm to about 35 μm and a d10 in a range of about 1.25 μm to about 15 μm; 
 the first SCM fraction has a d90 in a range of greater than 1 μm to about 15 μm; and 
 the second SCM fraction has a d90 in a range of about 30 μm to about 300 μm and a d10 in a range of about 10 μm to about 90 μm. 
 
     
     
       17. A cement-SCM blend as in  claim 5 , wherein:
 the narrow PSD hydraulic cement fraction has a d90 in a range of 12 μm to about 30 μm and a d10 in a range of about 2 μm to about 12 μm; 
 the first SCM fraction has a d90 in a range of about 2 μm to about 12 μm; and 
 the second SCM fraction has a d90 in a range of about 40 μm to about 200 μm and a d10 in a range of about 12.5 μm to about 60 μm. 
 
     
     
       18. A cement-SCM blend as in  claim 5 , wherein:
 the narrow PSD hydraulic cement fraction has a d90 in a range of 15 μm to about 30 μm and a d10 in a range of about 3 μm to about 10 μm; 
 the first SCM fraction has a d90 in a range of about 3 μm to about 10 μm; and 
 the second SCM fraction has a d90 in a range of about 50 μm to about 150 μm and a d10 in a range of about 15 μm to about 40 μm. 
 
     
     
       19. A method as in  claim 11 , wherein the narrow PSD hydraulic cement is processed using one or more of a vertical roller mill, rod mill, roll press, ball mill, hammer mill, jet mill, dry bead mill, or ultrasonic comminuting mill, alone or in combination with one or more of a high efficiency classifier or sieve. 
     
     
       20. A method as in  claim 11 , wherein the at least one SCM is processed using one or more of a vertical roller mill, rod mill, roll press, ball mill, hammer mill, jet mill, dry bead mill, or ultrasonic comminuting mill, alone or in combination with one or more of a high efficiency classifier or sieve. 
     
     
       21. A cement-SCM blend as in claim 1, wherein:
 the narrow PSD hydraulic cement fraction has a d90 of at least 8 μm, a d50 in a range of 3 μm to 25 μm, and a d10 in a range of 1 μm to 15 μm; and   the at least two SCM fractions include:
 a first SCM fraction having a d10 in a range of 0.01 μm to 4 μm; and 
 a second SCM fraction having a d90 in a range of 30 μm to 300 μm.