Class C fly ash-based cementitious materials, flowable fill, concrete, and related techniques
Class C fly ash-based cementitious materials, concretes, and related techniques are disclosed. In accordance with some embodiments, an activated class C fly ash-based cementitious material may be produced by intergrinding class C fly ash (e.g., classified to remove quartz and/or other contaminants and, thus, increase the reactive materials present), an activator, sodium citrate, borax, and a polycarboxylate material. The class C fly ash may have an amorphous glass content of about 60 wt % or more, a calcium oxide (CaO 2 ) content of about 20 wt % or more, and a quartz content of about 10 wt % or less. The activator may be a chemical which reacts with class C fly ash to form strätlingite structures therein when introduced with water. In some cases, the cementitious material may be provided as an all-in-one powder blend. In some cases, techniques disclosed herein may be utilized in providing a fast-setting flowable fill material.
1. A class C fly ash-based cementitious mixture comprising:
class C fly ash;
an activator comprising potassium hydroxide (KOH) and triethanolamine (TEA); and
at least two of sodium citrate, borax, and a polycarboxylate material.
2. The cementitious mixture of claim 1 , wherein the activator reacts with the class C fly ash to form strätlingite structures therein when introduced with water.
3. The cementitious mixture of claim 1 , comprising each of:
sodium citrate;
borax; and
the polycarboxylate material.
4. The cementitious mixture of claim 1 , wherein in comprising at least two of sodium citrate, borax, and the polycarboxylate material, the cementitious mixture includes the polycarboxylate material.
5. The cementitious mixture of claim 1 , wherein the class C fly ash constitutes about 90-99 wt % of the class C fly ash-based cementitious mixture.
6. The cementitious mixture of claim 1 , wherein the class C fly ash has:
an amorphous glass content in the range of 60 wt % or more;
a calcium oxide (CaO 2 ) content in the range of 20 wt % or more; and
a quartz content in the range of 10 wt % or less.
7. The cementitious mixture of claim 1 , wherein the class C fly ash has:
an amorphous glass content in the range of about 50-70 wt %;
a calcium oxide (CaO 2 ) content in the range of about 15-30 wt %; and
a quartz content in the range of about 5-20 wt %.
8. The cementitious mixture of claim 1 , wherein the activator constitutes about 0.25-1.0 wt % of the class C fly ash-based cementitious mixture.
9. The cementitious mixture of claim 1 , wherein the sodium citrate constitutes about 0.5-5.0 wt % of the class C fly ash-based cementitious mixture.
10. The cementitious mixture of claim 1 , wherein the borax constitutes about 0.1-0.5 wt % of the class C fly ash-based cementitious mixture.
11. The cementitious mixture of claim 1 , wherein the polycarboxylate material constitutes about 0.1-0.5 wt % of the class C fly ash-based cementitious mixture.
12. A concrete comprising:
the cementitious mixture of claim 1 ;
water; and
at least one of rock and sand.
13. The concrete of claim 12 , wherein the class C fly ash-based cementitious mixture constitutes about 10-17 wt % of the concrete.
14. The concrete of claim 12 , wherein the concrete has a water-cement (w/c) ratio in the range of about 0.23-0.4.
15. A concrete product comprising the cementitious mixture of claim 1 .
16. A class C fly ash-based cementitious mixture comprising:
class C fly ash;
an activator comprising potassium hydroxide (KOH) and triethanolamine (TEA); and
at least one of sodium citrate, borax, and a polycarboxylate material, wherein in comprising at least one of sodium citrate, borax, and the polycarboxylate material, the cementitious mixture includes at least sodium citrate.
17. A concrete comprising:
the cementitious mixture of claim 5 ;
water; and
at least one of rock and sand.
18. A concrete product comprising the cementitious mixture of claim 16 .
19. A class C fly ash-based cementitious mixture comprising:
class C fly ash;
an activator comprising potassium hydroxide (KOH) and triethanolamine (TEA); and
at least one of sodium citrate, borax, and a polycarboxylate material, wherein in comprising at least one of sodium citrate, borax, and the polycarboxylate material, the cementitious mixture includes at least borax.
20. A concrete comprising:
the cementitious mixture of claim 6 ;
water; and
at least one of rock and sand.
21. A concrete product comprising the cementitious mixture of claim 19 .