Classification and recombination of different SCM and cement fractions to efficiently manufacture cement-SCM compositions
Methods and systems for efficiently manufacturing particulate blending materials for use in making particle size optimized cements, SCMs, blended cements and cement-SCM blends. An initial hydraulic cement or SCM having an initial particle size distribution (PSD), an initial d10, and an initial d90 is processed using one or more air classifiers, and optionally one or more mills, to yield a plurality of hydraulic cement or SCM fractions having desired particle size distributions (PSDs). The hydraulic cement fractions can be blended with SCMs to form binary and ternary cement-SCM blends. The SCM fractions can also be used to make binary and ternary blends. A surplus fine cement fraction can be used to raise the fineness and/or reactivity of a less fine and/or less reactive hydraulic cement. A surplus fine SCM can be used as a silica fume substitute.
1. A method for manufacturing a plurality of different cement-SCM blends, comprising:
classifying an initial supplementary cementitious material (SCM) using an air classifier to produce fine SCM and coarse SCM;
blending the fine SCM but not the coarse SCM with a first hydraulic cement to produce a first cement-SCM blend;
grinding the coarse SCM to form ground SCM; and
blending the ground SCM but not the fine SCM with a second hydraulic cement to produce a second cement-SCM blend.
2. The method of claim 1 , further comprising grinding one or more SCMs to form the initial SCM prior to classifying to form the fine SCM and the coarse SCM.
3. The method of claim 1 , wherein the initial SCM is selected from the group consisting of coal ash, metallurgical slag, biomass ash, post-consumer glass, ground granulated blast furnace slag, steel slag, fly ash, volcanic ash, natural pozzolans, calcined shale, metakaolin, quarry fines, trass, ground limestone, ground quartz, ground siliceous materials, precipitated CaCO 3 , and precipitated MgCO 3 .
4. The method of claim 1 , further comprising grinding the fine SCM prior to blending with the first hydraulic cement.
5. The method of claim 1 , wherein the fine SCM is finer than the first hydraulic cement.
6. The method of claim 1 , wherein the ground SCM is finer than the second hydraulic cement.
7. The method of claim 1 , wherein the coarse SCM is blended with the second hydraulic cement without intergrinding.
8. The method of claim 1 , wherein the coarse SCM is ground and blended with the second hydraulic cement by intergrinding.
9. The method of claim 1 , wherein the ground SCM is coarser than the second hydraulic cement.
10. The method of claim 1 , further comprising intergrinding the coarse SCM with another SCM to form the ground SCM.
11. The method of claim 1 , further comprising blending a portion of the fine SCM with the second cement-SCM blend to form a third cement-SCM blend.
12. The method of claim 1 , further comprising blending a portion of the ground SCM with the first cement-SCM blend to form a fourth cement-SCM blend.
13. A method for manufacturing a plurality of different cement-SCM blends, comprising:
classifying fly ash using an air classifier to produce fine fly ash and coarse fly ash;
blending the fine fly ash but not the coarse fly ash with a first hydraulic cement to produce a first cement-SCM blend;
grinding the coarse fly ash to form ground fly ash; and
blending the ground fly ash but not the fine fly ash with a second hydraulic cement to produce a second cement-SCM blend.
14. The method of claim 13 , further comprising grinding the fine fly ash prior to blending with the hydraulic cement.
15. The method of claim 13 , wherein the coarse fly ash is blended with the second hydraulic cement without intergrinding.
16. The method of claim 13 , wherein the coarse fly ash is ground and blended with the second hydraulic cement by intergrinding.
17. The method of claim 13 , further comprising blending a portion of the fine fly ash with the second cement-SCM blend to form a third cement-SCM blend.
18. The method of claim 13 , further comprising blending a portion of the ground fly ash with the first cement-SCM blend to form a fourth cement-SCM blend.
19. A method for manufacturing a plurality of different cement-SCM blends, comprising:
classifying an initial supplementary cementitious material (SCM) using an air classifier to produce fine SCM and coarse SCM, wherein the initial SCM is selected from the group consisting of coal ash, metallurgical slag, biomass ash, post-consumer glass, ground granulated blast furnace slag, steel slag, fly ash, volcanic ash, natural pozzolans, calcined shale, metakaolin, quarry fines, trass, ground limestone, ground quartz, ground siliceous materials, precipitated CaCO 3 , and precipitated MgCO 3 ;
blending the fine SCM but not the coarse SCM with a first Portland cement to produce a first cement-SCM blend;
grinding the coarse SCM to form ground SCM; and
blending the ground SCM but not the fine SCM with a second Portland cement to produce a second cement-SCM blend.
20. The method of claim 19 , further comprising:
blending a portion of the fine SCM with the second cement-SCM blend to form a third cement-SCM blend; or
blending a portion of the ground SCM with the first cement-SCM blend to form a fourth cement-SCM blend.