초록 ▼

Cementitious compositions in which the cementitious properties of fly ash are carefully controlled are described. The cementitious compositions may be substantially free harsh acids and bases such as citric acids (≈pH 2.2) and alkali metal activators including alkali hydroxides (≈pH 12-14) and metal

Cementitious compositions in which the cementitious properties of fly ash are carefully controlled are described. The cementitious compositions may be substantially free harsh acids and bases such as citric acids (≈pH 2.2) and alkali metal activators including alkali hydroxides (≈pH 12-14) and metal carbonates (≈pH 11.6). The use of these harsh chemicals creates acid base reactions during use of the products. Instead of these harsh chemicals, a lactic acid salt based activator is be used as a reaction accelerator. Boric compounds may be used as a retarder in the compositions.

대표청구항 ▼

1. A cementitious composition comprising: coal fly ash-based pozzolans; anda chemical activator based on lactic acid comprising more than 50% by weight of the total weight of activators in the cementitious composition,wherein the total weight of activators in the cementitious composition comprises 0

1. A cementitious composition comprising: coal fly ash-based pozzolans; anda chemical activator based on lactic acid comprising more than 50% by weight of the total weight of activators in the cementitious composition,wherein the total weight of activators in the cementitious composition comprises 0.1 to 30% of the total weight of the cementitious composition, and the cementitious composition is substantially free of Portland cement. 2. The cementitious composition of claim 1, wherein the chemical activator is a pH neutral salt of lactic acid. 3. The cementitious composition of claim 2, wherein the chemical activator comprises potassium lactate, sodium lactate, lithium lactate, calcium lactate, or magnesium lactate. 4. The cementitious composition of claim 2, wherein the pH neutral salt comprises an alkaline metal or alkaline earth. 5. The cementitious composition of claim 1, wherein cementitious composition further comprises a chemical retarder. 6. The cementitious composition of claim 5, wherein the retarder comprises a boron compound. 7. The cementitious composition of claim 6, wherein the boron compound is selected from the group consisting of boric acid, boric oxide, sodium borate, sodium tetraborate, potassium borate and potassium tetraborate, borax pentahydrate, and borax decahydrate. 8. The cementitious composition of claim 1, wherein cementitious composition is substantially free of citric acid activators, alkali metal activators, and metal carbonate activators. 9. The cementitious composition of claim 1, wherein the chemical activator based on lactic acid comprises more than 95% by weight of the total weight of activators in the cementitous composition. 10. The cementitious composition of claim 1, wherein the cementitous composition has a set time of between 2 hours and 24 hours. 11. The cementitious composition of claim 1, coal fly ash based pozzolans are selected from the group consisting of Class C fly-ash, Class F fly-ash, Class N pozzolanic ash and combinations thereof. 12. The cementitious composition of claim 10, wherein the composition has a silica to calcia molar ratio of between about 1.2:1 and about 1.4:1. 13. The cementitious composition of claim 5, wherein the retarder is dissolved in a solution of activator in a concentration between 0.1% and 30.0%. 14. The cementitious composition of claim 5, wherein the retarder is dissolved in a solution of activator in a concentration between 10.0% and 30.0%. 15. A method of forming a hardened cement composition comprising: mixing a hydratable composition comprising coal fly ash-based pozzolans anda chemical activator based on lactic acid comprising more than 50% by weight of the total weight of activators in the cementitious composition, to form a hardened cement composition,wherein the total weight of activators in the cementitious composition comprises 0.1 to 30% of the total weight of the cementitious composition, and the cementitious composition is substantially free of Portland cement. 16. The method of claim 15, wherein the chemical activator is a pH neutral salt of lactic acid. 17. The method of claim 15, wherein the chemical activator comprises potassium lactate, sodium lactate, lithium lactate, calcium lactate, or magnesium lactate. 18. The method of claim 16, wherein the pH neutral salt comprises an alkaline metal or alkaline earth. 19. The method of claim 15, further comprising mixing a chemical retarder with the hydratable composition comprising coal fly ash-based pozzolans and the chemical activator. 20. The method of claim 19, wherein the retarder comprises a boron compound. 21. The method of claim 20, wherein the boron compound is selected from the group consisting of boric acid, boric oxide, sodium borate, sodium tetraborate, potassium borate and potassium tetraborate, borax pentahydrate, and borax decahydrate. 22. The method of claim 15, wherein citric acid activators, alkali metal activators, and metal carbonate activators are not mixed with the hydratable composition comprising coal fly ash-based pozzolans to form the hardened cement composition. 23. The method of claim 15, wherein the chemical activator based on lactic acid comprises more than 95% by weight of the total weight of activators used to form the hardened cement composition. 24. The method of claim 15, wherein the hydratable composition comprising coal fly ash-based pozzolans has a set time of greater than 2 hours after mixing with the chemical activator based on lactic acid. 25. The method of claim 15, wherein the hydratable composition comprising coal fly ash-based pozzolans comprises pozzolans selected from the group consisting of Class C fly-ash, Class F fly-ash, Class N pozzolanic ash and combinations thereof. 26. The method of claim 15, further comprising dissolving a retarder in a solution comprising the chemical activator in a concentration of between 0.1% and 40%. 27. The method of claim 15, further comprising dissolving a retarder in a solution separate from the chemical activator in a concentration of between 0.1% and 40%.