Cementitious material reinforced with chemically treated cellulose fiber
View Patent ↗The present invention relates to a fiber-reinforced cement based or cementitious material, and process for making, where the reinforcing fiber is a chemically treated cellulose or non-cellulose fiber. The fiber reinforced cementitious material includes (i) cement, (ii) optionally, sand, aggregate, or sand and aggregate, and (iii) chemically treated fibers having a polyvalent cation content of from about 0.1 weight percent to about 5.0 weight percent based on the dry weight of the treated fibers. The present invention further provides for a fiber reinforced cementitious material having a weak acid content of from about 0.5 weight percent to about 10 weight percent based on the dry weight of the treated fibers.
1. A poured concrete structure containing a cementitious mixture comprising:
(A) cement,
(B) optionally, sand, aggregate, or sand and aggregate, and
(C) chemically treated cellulose fibers having a polyvalent cation content of from about 0.1 weight percent to about 5.0 weight percent based on the dry weight of the treated fibers, and having a buffer salt content, a buffer salt weak acid combination content, an insoluble metal hydroxide content or an antioxidant content of from about 0.5 weight percent to about 10 weight percent based on the dry weight of the treated fibers.
2. The poured concrete structure of claim 1 , wherein the concrete has a freeze/thaw durability factor as measured by ASTM C 666 of about 37 percent or greater.
3. A cellulose fiber reinforced cementitious mixture comprising:
(A) cement,
(B) optionally, sand, aggregate, or sand and aggregate, and
(C) chemically treated cellulose fibers having a polyvalent cation content of from about 0.1 weight percent to about 5.0 weight percent based on the dry weight of the treated fibers, and having a buffer salt content of from about 0.5 weight percent to about 10 weight percent based on the dry weight of the treated fibers, wherein the buffer salt in water provides a solution having a pH of less than about 7 is suitable.
4. The cementitious mixture of claim 3 , wherein the buffer salt comprises at least one of sodium acetate, sodium oxalate, sodium tartrate, sodium phthalate, sodium dihydrogen phosphate, disodium hydrogen phosphate and sodium borate.
5. The cementitious mixture of claim 3 , wherein the buffer salt comprises a buffer salt weak acid combination comprising at least one of oxalic acid/sodium oxalate, tartaric acid/sodium tartrate, sodium phthalate/phthalic acid, and sodium dihydrogen phosphate/disodium hydrogen phosphate.
6. The cementitious mixture of claim 3 , wherein the polyvalent metal-containing compound is used in combination with an insoluble metal hydroxide or in combination with one or more alkali stable anti-oxidant chemicals or alkali stable reducing agents that would inhibit fiber degradation in an alkaline oxygen environment.
7. The cementitious mixture of claim 6 , wherein the insoluble metal hydroxide is magnesium hydroxide.
8. The cementitious mixture of claim 6 , wherein the inorganic chemical is sodium sulfite.
9. The cementitious mixture of claim 6 , wherein the organic chemical is hydroquinone.
10. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has a WRV which is about 70 percent or greater of the WRV of the untreated fiber from which the treated fiber is produced.
11. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has a 24 hour ZSSR for NaOH treatment, as determined by a procedure based on TAPPI method T231 using 20 percent consistency for sealed bag testing of about 1.0 or greater.
12. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has an increase in ZSSR relative to that of the same fiber without chemical treatment of about 5 percent or greater.
13. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has been treated with from about 1 weight percent to about 20 weight percent of a polyvalent metal-containing compound, based on the dry weight of the untreated fiber.
14. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has been treated with a polyvalent metal-containing compound in which the polyvalent metal is in the 3+ oxidation state.
15. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has been treated with a compound selected from the group consisting of an aluminum-containing compound, an iron (III)-containing compound and a combination thereof.
16. The cementitious material of claim 15 , wherein the chemically treated cellulose fiber has been treated with an aluminum-containing compound.
17. The cementitious material of claim 16 , wherein the chemically treated cellulose fiber has been treated with aluminum sulfate.
18. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has been treated with an acid selected from the group consisting of citric acid, oxalic acid, malonic acid, lactic acid and a mixture thereof.
19. The cementitious material of claim 18 , wherein the chemically treated cellulose fiber has been treated with an aluminum-containing compound and citric acid.
20. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber content of the cementitious material is from about 0.01 weight percent to about 20 weight percent based on the weight of the cementitious material.
21. The cementitious material of claim 3 , wherein the cementitious material contains from about 0.1 kg/m 3 to about 30 kg/m 3 of the chemically treated cellulose fiber.
22. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber is present in the form of a reinforcement mixture comprising one or more other reinforcement materials or additives.
23. The cementitious material of claim 22 , wherein the reinforcement mixture contains chemically treated cellulose fibers and one or more of thermoplastic fibers, polyolefin fibers, polyethylene fibers, polyester fibers nylon fibers, polyamide fibers, polyacrylonitrile fibers, polyacrylamide fibers, viscose fibers, PVC fibers, PVA fibers, metal fibers, carbon fibers, ceramic fibers, steel fibers, glass fibers, carbon fibers, natural organic and mineral fibers, abaca, asbestos, bamboo, coconut, cotton, jute, sisal, wood, rockwool, polypropylene fibers, kevlar, and rayon.
24. The cementitious material of claim 3 , wherein the material contains a latex or a mixture of lattices.
25. The cementitious material of claim 3 , where the chemically treated cellulose fibers have a Molecular Weight Stability Ratio (MWSR) of about 0.82 or greater.
26. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber remains discrete with its integrity intact.
27. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has been derived from one or more of Southern Softwood Kraft, Northern Softwood Kraft, hardwood, eucalyptus, mechanical, recycle and rayon.
28. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber is made from cellulose fibers that have been bleached to reduce the content of lignin.
29. The cementitious material of claim 3 , wherein the chemically treated cellulose fiber has a TFASI(V) of about 1.05 or greater.
30. A non-cellulosic fiber reinforced cementitious material comprising
(A) cement,
(B) optionally, sand, aggregate, or sand and aggregate, and
(C) chemically treated non-cellulosic fibers having a polyvalent cation content of from about 0.1 weight percent to about 5.0 weight percent based on the dry weight of the treated fibers, and having a buffer salt content, a buffer salt weak acid combination content, an insoluble metal hydroxide content or an antioxidant content of from about 0.5 weight percent to about 10 weight percent based on the dry weight of the treated fibers.