Pozzolanic compositions containing fly ash and remediation agents for use in cementitious materials
It has been unexpectedly discovered that the addition of a natural or other pozzolan to non-spec fly ash significantly improves the properties of the non-spec fly ash to the extent it can be certified under ASTM C618 and AASHTO 295, as either a Class F or Class C fly ash. The natural pozzolan may be a volcanic ejecta, such as pumice or perlite. Other pozzolans may also be used for this beneficiation process. Many pozzolans are experimentally tested and may be used to beneficiate non-spec fly ash into certifiable Class F fly ash. Additionally, this disclosure provides a method of converting a Class C fly ash to a more valuable Class F fly ash. This discovery will extend diminishing Class F fly ash supplies and turn non-spec fly ash waste streams into valuable, certified fly ash pozzolan which will protect and enhance concrete, mortars and grouts.
1. A pozzolanic composition for use in concrete, said composition comprising coal ash combined with a natural pozzolan, wherein said natural pozzolan is present in a concentration of about 1 wt % to about 99 wt %, wherein the combination of said natural pozzolan with said coal ash results in said pozzolanic composition meeting a specification for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO.
2. The pozzolanic composition of claim 1 , wherein said natural pozzolan is present in a concentration of about 10 wt % to about 90 wt %.
3. The pozzolanic composition of claim 1 , wherein a weight ratio of said natural pozzolan to said coal ash is from about 0.01 to about 100 parts natural pozzolan divided by parts coal ash.
4. The pozzolanic composition of claim 3 , wherein a weight ratio of said natural pozzolan to said coal ash is from about 0.1 to about 10 parts natural pozzolan divided by parts coal ash.
5. The pozzolanic composition of claim 1 , wherein said natural pozzolan is a volcanic ash with pozzolanic properties.
6. The pozzolanic composition of claim 1 , wherein said natural pozzolan is a material defined as a natural pozzolan pursuant to ASTM and/or AASHTO.
7. The pozzolanic composition of claim 1 , wherein said coal ash is a non-spec ash that does not meet any specifications for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO.
8. The pozzolanic composition of claim 7 , wherein said coal ash contains less than 50 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide.
9. The pozzolanic composition of claim 1 , wherein said coal ash meets a first specification for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO, wherein said combination of said natural pozzolan with said coal ash results in said pozzolanic composition meeting a second specification for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO.
10. The pozzolanic composition of claim 9 , wherein said coal ash contains at least 50 wt % but less than 70 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide, wherein said first specification requires at least 50 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide, and wherein said second specification requires at least 70 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide.
11. The pozzolanic composition of claim 1 , said composition further comprising an additive to adjust water demand of said composition in concrete.
12. The pozzolanic composition of claim 1 , wherein said composition is present in a cementitious mixture.
13. A concrete product or structure comprising aggregate and said cementitious mixture of claim 12 , or a reaction product thereof.
14. A method of producing a pozzolanic composition for use in concrete, said method comprising:
providing a source of coal ash;
providing a natural pozzolan; and
combining said coal ash with said natural pozzolan, to produce a pozzolanic composition meeting a specification for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO, wherein said coal ash is upgraded by the presence of said natural pozzolan to enhance its pozzolanic properties prior to addition of said pozzolanic composition to said concrete.
15. The method of claim 14 , wherein said natural pozzolan is present in a concentration of about 1 wt % to about 99 wt % in said pozzolanic composition.
16. The method of claim 15 , wherein said natural pozzolan is present in a concentration of about 10 wt % to about 90 wt % in said pozzolanic composition.
17. The method of claim 14 , wherein said natural pozzolan is a material defined as a natural pozzolan pursuant to ASTM and/or AASHTO.
18. The method of claim 14 , wherein said coal ash is a non-spec ash that does not meet any specifications for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO.
19. The method of claim 14 , wherein said coal ash meets a first specification for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO, wherein said combination of said natural pozzolan with said coal ash results in said pozzolanic composition meeting a second specification for pozzolanic mixtures, pozzolan admixtures, or supplementary cementitious materials in concrete under ASTM and/or AASHTO.
20. The method of claim 19 , wherein said coal ash contains at least 50 wt % but less than 70 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide, wherein said first specification requires at least 50 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide, and wherein said second specification requires at least 70 wt % of the sum of weight percent silicon dioxide, weight percent aluminum oxide, and weight percent iron oxide.