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 method comprising:
producing a class C fly ash-based cementitious mixture comprising:
class C fly ash;
an activator which reacts with the class C fly ash to form strätlingite structures therein when introduced with water, wherein the activator comprises potassium hydroxide (KOH) and triethanolamine (TEA);
sodium citrate;
borax; and
a polycarboxylate material.
2. The method of claim 1 , wherein the class C fly ash constitutes about 90-99 wt % of the class C fly ash-based cementitious mixture.
3. The method 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.
4. The method 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 %.
5. The method of claim 1 , wherein the activator constitutes about 0.25-1.0 wt % of the class C fly ash-based cementitious mixture.
6. The method of claim 1 , wherein the sodium citrate constitutes about 0.5-5.0 wt % of the class C fly ash-based cementitious mixture.
7. The method of claim 1 , wherein the borax constitutes about 0.1-0.5 wt % of the class C fly ash-based cementitious mixture.
8. The method of claim 1 , wherein producing the class C fly ash-based cementitious mixture involves intergrinding the class C fly ash, the activator, the sodium citrate, the borax, and the polycarboxylate material.
9. The method of claim 8 , wherein the intergrinding is performed for about 10±5 minutes.
10. The method of claim 8 , wherein the intergrinding is performed until a D90 particle size distribution in the range of about 30-60 μm is achieved for the class C fly ash-based cementitious mixture.
11. The method of claim 8 , wherein prior to the intergrinding, the class C fly ash is classified to remove at least one of quartz, an unreactive element, and a contaminant.
12. A method comprising:
producing a concrete comprising:
the class C fly ash-based cementitious mixture produced according to claim 1 ;
water; and
at least one of rock and sand.
13. The method of claim 12 , wherein the class C fly ash-based cementitious mixture constitutes about 10-17 wt % of the concrete.
14. The method of claim 12 , wherein the concrete has a water-cement (w/c) ratio in the range of about 0.23-0.4.
15. The method of claim 12 , wherein the concrete has a water-cement (w/c) ratio in the range of about 0.23-0.3.
16. A concrete product comprising concrete produced according to claim 12 .
17. A method comprising:
producing a class C fly ash-based cementitious mixture comprising:
class C fly ash having:
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;
an activator which reacts with the class C fly ash to form strätlingite structures therein when introduced with water, wherein the activator comprises potassium hydroxide (KOH) and triethanolamine (TEA);
sodium citrate;
borax; and
a polycarboxylate material;
wherein producing the class C fly ash-based cementitious mixture involves:
classifying the class C fly ash to remove at least one of quartz, an unreactive element, and a contaminant; and
intergrinding the class C fly ash, the activator, the sodium citrate, the borax, and the polycarboxylate material.
18. A method comprising:
producing a concrete comprising:
the class C fly ash-based cementitious mixture produced according to claim 17 ;
water; and
at least one of rock and sand;
wherein the concrete has a water-cement (w/c) ratio in the range of about 0.23-0.3.
19. A concrete product comprising concrete produced according to claim 18 .