Cement composition and product

• US 4,410,366 A
• Filed: 12/14/1981
• Issued: 10/18/1983
• Est. Priority Date: 12/22/1980
• Status: Expired due to Term

• Current Assignee: Imperial Chemical Industries PLC (IMPERIAL CHEMICAL INDUSTRIES)
• Original Assignee: Imperial Chemical Industries PLC (IMPERIAL CHEMICAL INDUSTRIES)
• Inventors: Kendall, Kevin, Birchall, James D., Howard, Anthony J., Raistrick, James H.
• Primary Examiner(s): Poer, James
• Application Number:
  US06/330,585
• Time in Patent Office: 673 Days
• Field of Search: 106/90, 106/314, 106/104
• US Class Current: 524/5
• CPC Class Codes: C04B 2111/00301 Non-porous materials, e.g. macro-defect free [MDF] products
• CPC Class Codes: C04B 24/2623 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 40/005 High shear mixing; Obtaining macro-defect free materials

Abstract

A cementitious composition comprising hydraulic cement, not more than 25% of water by weight of the composition, and water soluble or dispersible (co)polymer in a proportion of 1 to 15% by weight of the hydraulic cement in the composition, the cement and (co)polymer being selected such that a test composition comprising 100 parts by weight of cement, 5 parts by weight of (co)polymer, and 16 parts by weight of water when extruded in a capillary rheometer undergoes an increase of at least 25% in shear stress when a ten-fold increase in the shear rate of the test composition from the capillary of the rheometer is effected. Also a cementitious product produced by setting of the composition. The (co)polymer is preferably a partially hydrolyzed poly (vinyl acetate). The cementitious product may have a flexural strength in excess of 100 MPa.

Claims

1. A cementitious composition comprising

(a) at least one hydraulic cement,

(b) water in a proportion of not more than 25% by weight of the composition, and

(c) at least one water-soluble or water-dispersible organic polymer or copolymer in a proportion of 1 to 15% by weight of the hydraulic cement in the composition,

characterised in that the hydraulic cement and the polymer or copolymer are selected such that a test composition comprising 100 parts by weight of hydraulic cement, 5 parts by weight of the polymer or copolymer, and 16 parts by weight of water then extruded in a capillary rheometer undergoes an increase of at least 25% in shear stress when a ten-fold increase in the shear rate of the test composition is effected when the shear rates as measured are within the range 0.1 to 5 second^-1.

2. A cementitious composition as claimed in claim 1 characterised in that the hydraulic cement and polymer or copolymer are selected such that the test composition undergoes an increase of at least 50% in shear stress when a ten-fold increase in the shear rate of the test composition is effected.

3. A cementitious composition as claimed in claim 1 characterised in that the organic polymer or copolymer is hydrolysed vinyl acetate polymer or copolymer.

4. A cementitious composition as claimed in claim 3 characterised in that the organic polymer or copolymer is hydrolysed poly(vinyl acetate).

5. A cementitious composition as claimed in claim 3 or claim 4 characterised in that the degree of hydrolysis of the vinyl acetate polymer or copolymer is at least 50%.

6. A cementitious composition as claimed in claim 5 characterised in that the degree of hydrolysis is in the range 70% to 90%.

7. A cementitious composition as claimed in claim 1 characterised in that the composition contains at least 3% of organic polymer or copolymer by weight of the hydraulic cement in the composition.

8. A cementitious composition as claimed in claim 1 characterised in that the hydraulic cement is an aluminous cement or a calcium silicate cement.

9. A cementitious composition as claimed in claim 1 characterised in that the composition contains not more than 18% by weight of water.

10. A cementitious composition as claimed in claim 1 characterised in that the composition contains particulate aggregate and in that the hydraulic cement and the polymer or copolymer are selected such that a test composition comprising hydraulic cement plus particulate aggregate (in total 100 parts by weight), 5 parts by weight of the polymer or copolymer, and 16 parts by weight of water when extruded in a capillary rheometer undergoes an increase of at least 25% in shear stress when a ten-fold increase in the shear rate of the test composition is effected when the shear rates as measured are within the range 0.1 to 5 second^-1.

11. A cementitious product produced by setting of a cementitious composition as claimed in claim 1.

12. A cementitious product as claimed in claim 11 characterised in that not more than 2% of the total volume of the product comprises pores having a maximum dimension exceeding 100 microns.

13. A cementitious product as claimed in claim 12 characterised in that not more than 0.5% of the total volume of the product comprises pores having a maximum dimension exceeding 15 microns.

14. A cementitious product as claimed in claim 11 characterised in that the product comprises a proportion of pores which is not more than 3% of the apparent volume of the product.

15. A cementitious product as claimed in claim 14 characterised in that the product comprises a proportion of pores which is not more than 1% of the apparent volume of the product.

18. A cementitious product as claimed in claim 11 having a flexural strength of at least 100 MPa.

19. A cementitious product as claimed in claim 18 having a flexural strength of at least 150 MPa.

16. A cementitious product characterised in that said product has a flexural strength of at least 100 MPa.

17. A cementitious product as claimed in claim 16 characterised in that said product has a flexural strength of at least 150 MPa.