Fast Setting Portland Cement Compositions With Alkali Metal Citrates And Phosphates With High Early-Age Compressive Strength and Reduced Shrinkage

• US 20150033989A1
• Filed: 07/30/2013
• Published: 02/05/2015
• Est. Priority Date: 07/30/2013
• Status: Active Grant

• Current Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Original Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Inventors: PEREZ-PENA, Marianela
• Granted Patent: US 9,994,484 B2
• Time in Patent Office: Days
• US Class Current: 106/691
• CPC Class Codes: C04B 14/12 Expanded clay
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 2103/12 Set accelerators
• CPC Class Codes: C04B 2111/0062 Gypsum-paper board like materials
• CPC Class Codes: C04B 2111/1006 Absence of well-defined organic compounds
• CPC Class Codes: C04B 2111/34 Non-shrinking or non-cracking materials
• CPC Class Codes: C04B 22/16 containing phosphorus in the anion, e.g. phosphates
• CPC Class Codes: C04B 24/04 Carboxylic acids; Salts, anhydrides or esters thereof
• CPC Class Codes: C04B 24/06 containing hydroxy groups
• CPC Class Codes: C04B 28/04 Portland cements
• CPC Class Codes: C04B 28/14 containing calcium sulfate cements gypsum-paper plates E04C
• CPC Class Codes: C04B 40/0082 making use of a rise in temperature, e.g. caused by an exothermic reaction
• CPC Class Codes: C04B 7/02 Portland cement
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

A method of making a rapid setting composition for cement boards is disclosed. Compositions including a hydraulic cement preferably portland cement, an alkali metal citrate such as tripotassium citrate, and a phosphate such as sodium trimetaphosphate, with optional gypsum, and no alkanolamine accelerant, and no fly ash based cement. An interaction between the alkali metal citrate and the phosphate increases the effectiveness of accelerating reactions of the portland cement without need for an alkanolamine accelerant, even in the presence of gypsum. This allows unexpected quick setting and increased early-age compressive strength without shrinkage in the cement board compositions.

Claims

1. A method of providing a fast setting cementitious mixture comprising:

water,

a cementitious reactive powder comprising a hydraulic cement including no more than 10% fly ash;

a set accelerating amount of an alkali metal citrate; and

a phosphate selected from the group consisting of sodium trimetaphosphate, potassium tripolyphosphate, sodium tripolyphosphate, tetrasodium pyrophosphate, tetrapotassium pyrophosphate, monopotassium phosphate, dicalcium phosphate, and mixtures thereof, and

wherein the mixture does not contain an alkanolamine.

2. The method of claim 1, wherein the mixture does not contain fly ash.

3. The method of claim 1 wherein the mixture further comprises 0 to 4 parts by wt. calcium sulfate per 100 parts by wt of cementitious reactive powder on a dry basis.

4. The method of claim 1, wherein the hydraulic cement is a Portland cement containing 5 to 15% ferrite phase.

5. The method of claim 1, wherein the salt is an alkali metal citrate selected from the group consisting of sodium citrate, a potassium citrate, and mixtures thereof.

6. The method of claim 1, wherein the phosphate is sodium trimetaphosphate and is provided in an amount of about 0.15 to 1.0 wt. % phosphate based on the weight of the cementitious reactive powder.

7. The method of claim 1, wherein the phosphate is provided in an amount of about 0.3 to 0.9 wt. % based on the weight of cementitious powder.

8. The method of claim 1, wherein the phosphate comprises sodium trimetaphosphate in an amount of about 0.15 to 0.90 wt. % and the alkali metal citrate is tripotassium citrate in an amount of about 1.0 to 4.5 wt. %, both based upon the weight of the cementitious reactive powder.

9. The method of claim 1, wherein the cementitious reactive powder comprises about 80 to 100 wt % portland cement, 0 to 20 wt % calcium aluminate cement, and 0 to 7 wt % calcium sulfate, based on the sum of the portland cement, calcium aluminate cement, and calcium sulfate.

10. The method of claim 1, wherein the mixture further comprises aggregate.

11. The method of claim 1, further comprising at least one member of the group consisting of set retarder, air-entraining agent, and superplasticizer.

12. The method of claim 1, wherein the mixture is mixed at a temperature of about 90°

F. to 135°

F. (32.2°

To 57.2°

C.) and wherein the mixture temperature is achieved within about 3 to 5 minutes after mixing by heating one or more of the components of the mixture.

13. A composition for cement board comprising a water settable mixture of:

a cementitious reactive powder comprising portland cement;

an alkali metal citrate an alkali metal citrate selected from the group consisting of sodium citrate, a potassium citrate, and mixtures thereof,

a phosphate selected from at least one member of the group consisting of sodium trimetaphosphate, potassium tripolyphosphate, sodium tripolyphosphate, tetrasodium pyrophosphate, tetrapotassium pyrophosphate, monopotassium phosphate, dicalcium phosphate, and mixtures thereof, and water,

wherein the mixture does not contain an alkanolamine.

14. The composition of claim 13, wherein the mixture contains no fly ash.

15. The composition of claim 13 wherein 0 to 4 parts by weight of gypsum per 100 parts by weight cementitious reactive powder is added to the mixture to help reduce staining without reducing the final setting time and compressive strength.

16. The composition of claim 13, wherein the mixture comprises about 1.0 to 4.5 wt. % tripotassium citrate based on the weight of the cementitious reactive powder and sodium trimetaphosphate in an amount of 0.05 to 1.5 wt % based upon the weight of the cementitious reactive powder.

17. The composition of claim 13, further comprising at least one member selected from the group consisting of expanded clay aggregate, set retarder, foaming agent, air-entraining agent, superplasticizer and mixtures thereof.

18. A composition comprising the reaction product of:

water; and

a cementitious reactive powder comprising portland cement;

an alkali metal citrate selected from the group consisting of sodium citrate, a potassium citrate, and mixtures thereof,

a phosphate selected from at least one member of the group consisting of sodium trimetaphosphate, potassium tripolyphosphate, sodium tripolyphosphate, tetrasodium pyrophosphate, tetrapotassium pyrophosphate, monopotassium phosphate, dicalcium phosphate, and mixtures thereof, and wherein the composition does not contain an alkanolamine.

19. The composition of claim 18, wherein the product does not contain fly ash.

20. The composition of claim 18, wherein the composition contains 0 to 4 parts by wt gypsum per 100 parts by wt. of the reactive powder, 1.0 to 4.5 wt. % alkali metal citrate based on the total weight of the reactive powder and gypsum and 0.05 to 1.5 wt % sodium trimetaphosphate based upon the weight of the cementitious reactive powder and gypsum.