Self-compacting engineered cementitious composite

• US 6,809,131 B2
• Filed: 07/10/2001
• Issued: 10/26/2004
• Est. Priority Date: 07/10/2000
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Kong, Hyun-Joon, Li, Victor C.
• Primary Examiner(s): SZEKELY, PETER A
• Application Number:
  US09/902,064
• Publication Number:
  US 20020019465A1
• Time in Patent Office: 1,204 Days
• Field of Search: 524/5
• US Class Current: 524/5
• CPC Class Codes: C04B 16/0625 Polyalkenes, e.g. polyethylene
• CPC Class Codes: C04B 16/0641 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 20/1018 with organic materials pigments or dyes C04B20/1096
• CPC Class Codes: C04B 20/1088 Water
• CPC Class Codes: C04B 2103/32 Superplasticisers
• CPC Class Codes: C04B 2103/44 Thickening, gelling or viscosity increasing agents
• CPC Class Codes: C04B 2111/00103 Self-compacting mixtures
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 40/0028 Aspects relating to the mixing step of the mortar preparation
• CPC Class Codes: Y02A 30/30 in transportation, e.g. on roads, waterways or railways

Abstract

Short fiber-reinforced engineering cementitious composites which are self-compacting, can be prepared by adding hydrophilic polymer fibers to a cement composition containing polymeric thickener and superplasticizer. The compositions are exceptionally ductile and exhibit many of the physical characteristics previously available only with hydrophobic high performance polyethylene fibers.

Claims

1. A self-compacting, fiber-reinforced engineered cementitious composite comprising:

cementitious material comprising;

cement and sand;

at least one polymeric thickener;

at least one superplasticizer; and

water; and

from 0.5 to 10 volume % of hydrophilic reinforcing fibers having a modulus (E) of about 35-50 GPa and a percent elongation of about 3-20%;

wherein the hydrophilic fibers are coated with an oiling agent comprising poly(oxymethylene).

2. The composite of claim 1 wherein the hydrophilic fibers comprise polyvinyl alcohol fibers.

3. The composite of claim 1 further comprising hydrophobic fibers.

4. The composite of claim 1 wherein the hydrophilic fibers have a tenacity of about 1000-2500 MPa.

5. The composite of claim 1 wherein the hydrophilic fibers have a modulus (E) of about 40-45 GPa.

6. The composite of claim 5 wherein the hydrophilic fibers have a diameter of about 10-60 μ

m.

7. The composite of claim 6 wherein the hydrophilic fibers have a length of about 5-30 mm.

23. The composite of claim 1 wherein the components are present in sufficient amounts such that when the composite is cured the resulting cured product has a first crack strength of 2.1-2.6 MPa and an ultimate tensile strength of 2.8-3.8 MPa.

24. The composite of claim 23 wherein the components are present in sufficient amounts such that when the composite is cured the resulting cured product has a tensile strain capacity of 3-7.5%.

25. The composite of claim 1 wherein the components are provided in such amounts that the composite has a water-cement ratio of about 25 wt % to about 60 wt %, a sand-cement ratio of about 20 wt % to about 160 wt %, a thickener-cement ratio of about 0.001 wt % to about 0.5 wt %, and a superplasticizer-cement ratio of about 0.1 wt % to about 5 wt %.

26. The composite of claim 1 wherein the fibers have been coated with 0.5-1.5 weight percent of the oiling agent.

8. A method of making a composite structural material (engineered cementitious composite), said method comprising:

mixing from 0.5 to 10 volume % of hydrophilic reinforcing fibers having a modulus (E) of about 35-50 GPa and a percent elongation of about 3-20% with cementitious material comprising cement and sand, at least one polymeric thickener, at least one superplasticizer, and water, wherein the hydrophilic fibers are coated with an oiling agent comprising poly(oxymethylene).

9. The method of claim 8 wherein the hydrophilic fibers comprise polyvinyl alcohol fibers.

10. The method of claim 8 further comprising hydrophobic fibers.

11. The method of claim 8 wherein the hydrophilic fibers have a tenacity of about 1000-2500 MPa.

12. The method of claim 11 wherein the hydrophilic fibers have a modulus (E) of about 40-45 GPa.

13. The method of claim 12 wherein the hydrophilic fibers have a diameter of about 10-60 μ

m.

14. The method of claim 13 wherein the hydrophilic fibers have a length of about 5-30 mm.

15. The method of claim 8 wherein the composite structural material is made without the use of any external vibration.

16. The method of claim 14 wherein the composite structural material is made without the use of any external vibration.

17. A method of making a composite structural material (engineered cementitious composite), said method comprising:

1) mixing powders of dry cement, sand, fly ash and defoamer;

2) mixing the dry powder mixture of

     1) with water;

3) mixing an aqueous solution of cellulose compound with the mixture of

     2);

4) mixing an aqueous solution of superplasticizer with the mixture of

     3); and

5) mixing hydrophilic fibers having a modulus (E) of about 35-50 GPa and a percent elongation of about 3-20% with the mixture of

     4), wherein the hydrophilic fibers are coated with an oiling agent comprising poly(oxymethylene).

18. The method of claim 17 wherein the components and the mixture of 2) are mixed for about 2 minutes, wherein the components of mixture 3) are mixed for about 5 to 10 minutes, and wherein the components of mixture 4) are mixed for about 2 minutes.

19. The method of claim 18 wherein additional water is mixed with the mixture of 5).

20. The method of claim 17 wherein the reinforcing hydrophilic fibers are pre-soaked in water before being mixed with the mixture of 4).

21. The method of claim 17 wherein the hydrophilic fibers are in random, discontinuous form.

22. The method of claim 17 wherein the hydrophilic fibers are provided in a bundle form.