Fast setting portland cement compositions with alkali metal citrates and phosphates with high early-age compressive strength and reduced shrinkage

Patent metadata

Field	Value
Publication number	US-9994484-B2
Application number	US-201313954581-A
Country	US
Kind code	B2
Filing date	Jul 30, 2013
Priority date	Jul 30, 2013
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

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.

First claim

What is claimed:

1. A composition for cement board comprising a water settable mixture of:
a cementitious reactive powder comprising 80 to 100 wt. % hydraulic cement and no more than 10 wt % fly ash, wherein the hydraulic cement comprises:
about 80 to 100 wt % said portland cement,
0 to 20 wt % calcium aluminate cement,
0 to 7 wt % calcium sulfate, and
0 to 5 wt. % other hydraulic cements;

an alkali metal citrate selected from the group consisting of sodium citrate, a potassium citrate, and mixtures thereof, wherein the mixture comprises the alkali metal citrate in an amount of about 1.0 to 4.5 wt. % based on the weight of the cementitious reactive powder,
sodium trimetaphosphate in an amount of about 0.05 to 1.5 wt % based upon the weight of the cementitious reactive powder, and
water,
wherein the mixture does not contain an alkanolamine,
wherein there is an absence of sodium carbonate, potassium carbonate, and lithium carbonate;
wherein other than the citrate and the phosphate there is an absence of inorganic set accelerator and an absence of set retarder.

2. The composition of claim 1 , wherein the mixture contains no fly ash.

3. The composition of claim 1 , wherein the cementitious reactive powder comprises 0.15 to 1.0 wt % sodium trimetaphosphate based upon the weight of the cementitious reactive powder.

4. The composition of claim 3 , wherein the mixture comprises:
about 2 to 4.5 wt. % tripotassium citrate based on the weight of the cementitious reactive powder, and
sodium trimetaphosphate in an amount of 0.15 to 0.9 wt % based on the weight of the cementitious reactive powder;
wherein the cementitious reactive powder comprises
about 95 to 100 wt % portland cement,
0 to 5 wt % calcium aluminate cement, and
0 to 5 wt % calcium sulfate, based on the sum of the portland cement, calcium aluminate cement, and calcium sulfate.

5. The composition of claim 1 , further comprising at least one member selected from the group consisting of expanded clay aggregate, foaming agent, air-entraining agent, superplasticizer and mixtures thereof.

6. The composition of claim 1 , wherein the cementitious reactive powder comprises 0.15 to 0.3 wt % sodium trimetaphosphate based upon the weight of the cementitious reactive powder.

7. The composition of claim 1 , wherein the cementitious reactive powder consists of:
about 80 to 100 wt % portland cement,
0 to 20 wt % calcium aluminate cement, and
0 to 7 wt % calcium sulfate.

8. A method for preparing the composition comprising the water settable mixture of claim 1 , comprising mixing:
water,
cementitious reactive powder comprising 80 to 100 wt. % hydraulic cement and no more than 10 wt. % fly ash, 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;

alkali metal citrate in a set accelerating amount of about 1.0 to 4.5 wt. % based on the weight of the cementitious reactive powder; and
sodium trimetaphosphate in an amount of about 0.05 to 1.5 wt. % based on the weight of the cementitious reactive powder,
to prepare the water settable mixture; and
wherein the mixture does not contain an alkanolamine,
wherein there is an absence of sodium carbonate, potassium carbonate, and lithium carbonate;
wherein other than the citrate and the phosphate there is an absence of inorganic set accelerator and an absence of set retarder.

9. The method of claim 8 , 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, wherein the cementitious reactive powder contains 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, and the composition contains 1.0 to 4.5 wt. % alkali metal citrate based on the total weight of the reactive powder and 0.15 to 1.0 wt % sodium trimetaphosphate based upon the weight of the cementitious reactive powder.

10. The method of claim 8 , wherein the cementitious reactive powder consists of:
about 80 to 100 wt % portland cement,
0 to 20 wt % calcium aluminate cement, and
0 to 7 wt % calcium sulfate.

11. A composition comprising the reaction product of a mixture of:
water;
a cementitious reactive powder comprising portland cement and no more than 10 wt % fly ash, wherein the cementitious reactive powder contains
about 80 to 100 wt % portland cement,
0 to 20 wt % calcium aluminate cement,
0 to 7 wt % calcium sulfate;

an alkali metal citrate selected from the group consisting of sodium citrate, a potassium citrate, and mixtures thereof, wherein the mixture comprises the alkali metal citrate in an amount equal to about 1.0 to 4.5 wt. % based on the weight of the cementitious reactive powder; and
sodium trimetaphosphate in an amount equal to 0.15 to 1.5 wt % based upon the weight of the cementitious reactive powder, and
wherein the composition does not contain an alkanolamine,
wherein there is an absence of sodium carbonate, potassium carbonate, and lithium carbonate;
wherein other than the citrate and the phosphate there is an absence of inorganic set accelerator and an absence of set retarder.

12. The composition of claim 11 , wherein the product does not contain fly ash.

13. The composition of claim 11 , wherein the composition contains the alkali metal citrate in an amount equal to 1.0 to 4.5 wt. % of the weight of the cementitious reactive powder and the sodium trimetaphosphate in an amount equal to 0.15 to 1.0 wt % based upon the weight of the cementitious reactive powder.

14. The composition of claim 13 , wherein the mixture comprises tripotassium citrate in an amount equal to about 1.0 to 4.5 wt. % based on the weight of the cementitious reactive powder and sodium trimetaphosphate in an amount equal to 0.15 to 0.6 wt % based upon the weight of the cementitious reactive powder.

15. The composition of claim 11 , consisting of the reaction product the mixture of:
the water; and
the cementitious reactive powder consisting of
60-100 wt % portland cement,
0-20 wt. % calcium aluminate cement,
0-5 wt % other hydraulic cement,
0-7 wt % calcium sulfate,
0-40 wt % pozzolans, and
0-7 wt % added lime, and
no more than 10 wt % of the cementitious reactive powder is fly ash;

the alkali metal citrate in an amount equal to 1.0 to 4.5 wt % of the cementitious reactive powder, the alkali metal citrate selected from the group consisting of sodium citrate, potassium citrate, and mixtures thereof,
the sodium trimetaphosphate in an amount equal to 0.05 to 1.5 wt. % of the cementitious reactive powder and
aggregates and fillers wherein the weight ratio of total aggregate and filler to cementitious reactive powder is 0.4-1.2:1;
superplasticizers in an amount equal to 0.1 to 0.5 wt. % of the cementitious reactive powder, wherein the superplasticizers are selected from the group consisting of polynapthalene sulfonates, polyacrylates, polycarboxylates, lignosulfonates, melamine sulfonates;
optionally at least one member selected from the group consisting of shrinkage control agents, coloring agents, thickeners;
optionally air entraining/foaming agent selected from at least one member of the group consisting of alkyl ether sulfate oligomers, vinsol wood resins, sulfonated hydrocarbons, fatty and resinous acids, aliphatic substituted aryl sulfonates, sodium abietate, saturated or unsatur

Assignees

• United States Gypsum Co
• United States Gypsym Company

Inventors

• Perez-Pena Marianela

Classifications

• C04B22/16

  containing phosphorus in the anion, e.g. phosphates · CPC title

• C04B2103/12

  Set accelerators · CPC title

• C04B2111/0062

  Gypsum-paper board like materials · CPC title

• C04B2111/34

  Non-shrinking or non-cracking materials · CPC title

• C04B28/04 Primary

  Portland cements · CPC title