Engineered self-cleaning cementitious composites

Patent metadata

Field	Value
Publication number	US-2017334781-A1
Application number	US-201515524132-A
Country	US
Kind code	A1
Filing date	Nov 3, 2015
Priority date	Nov 3, 2014
Publication date	Nov 23, 2017
Grant date	—

Abstract

The present invention relates to a cementitous composite specifically engineered to possess self-cleaning abilities while maintaining their unique strain-hardening behaviour and the preparation of the said composite. The cementitious composite comprises a hydraulic cement, a plurality of fibers, in particular polyvinyl alcohol fibers wherein the ratio of the plurality of fibers to the hydraulic cement is in a range from 1 to 3% by volume; a self-cleaning agent, in particular nanoparticulate titanium dioxide (TiO 2 ) wherein the weight ratio of the self-cleaning agent to the hydraulic cement is in a range from 0.01 to 1.

First claim

1 . A cementitious mixture for preparing a ductile self-cleaning cementitious composite, the cementitious mixture comprising:
a hydraulic cement; water, wherein the ratio of water to the hydraulic cement is a range from 0.2 to 1 by weight; a plurality of fibers, wherein the average length of each fiber is in a range from 4 to 30 mm, wherein the ratio of the plurality of fibers to the hydraulic cement is in a range from 1 to 3% by volume; and a self-cleaning agent, wherein the ratio of the self-cleaning agent to the hydraulic cement is in a range from 0.01 to 1 by weight.

2 . The cementitious mixture of claim 1 , wherein the self-cleaning agent is selected from the group consisting of nanoparticles of titanium dioxide (TiO 2 ), zinc oxide (ZnO), iron (III) oxide (Fe 2 O 3 ), cadmium sulfide (CdS), zinc sulfide (ZnS), tungsten (VI) oxide (WO 3 ), copper (I) oxide (Cu 2 O), silver phosphate (Ag 3 PO 4 ), strontium titanate (SrTiO 3 ), barium titanate (BaTiO 3 ), calcium titanate (CaTiO 3 ), and a mixture thereof.

3 . The cementitious mixture of claim 2 , wherein the self-cleaning agent is TiO 2 nanoparticles.

4 . The cementitious mixture of any one of claims 1 to 3 , wherein the ratio of the self-cleaning agent to the hydraulic cement is in a range from 0.05 to 0.1 by weight.

5 . The cementitious mixture of claim 4 , wherein self-cleaning agent is TiO 2 nanoparticles and the ratio of TiO 2 nanoparticles to the hydraulic cement is 0.05 or 0.1 by weight.

6 . The cementitious mixture of any one of claims 1 to 5 , wherein the hydraulic cement is selected from the group consisting of Portland cement, blended Portland cement, expansive cement, rapid setting and hardening cement, calcium aluminate cement, magnesium phosphate, and a mixture thereof.

7 . The cementitious mixture of claim 6 , wherein the hydraulic cement comprises Type I white Portland cement.

8 . The cementitious mixture of any one of claims 1 to 7 , wherein the plurality of fibers are selected from a group consisting of polypropylene (PP) fibers, aromatic polyamide fibers, high modulus polyethylene (PE) fibers, polyvinyl alcohol (PVA) fibers, steel fibers, and a mixture thereof.

9 . The cementitious mixture of claim 8 , wherein the plurality of fibers are PVA fibers.

10 . The cementitious mixture of claim 9 , wherein the ratio of the plurality of PVA fibers to the hydraulic cement is 2% by volume.

11 . The cementitious mixture of any one of claims 1 to 10 , further comprising a viscosity control agent, wherein the ratio of viscosity control agent to the hydraulic cement is in a range from 0.001 to 0.05 by weight.

12 . The cementitious mixture of claim 11 , wherein the viscosity control agent comprises methylcellulose, polyvinyl alcohol, or starch.

13 . The cementitious mixture of any one of claims 1 to 12 , further comprising a water reducing agent, wherein the ratio of water reducing agent to the hydraulic cement is in a range from 0.005 to 0.07 by weight.

14 . The cementitious mixture of claim 13 , wherein the water reducing agent comprises a polycarboxylate-based superplasticizer and the ratio of the water reducing agent to the hydraulic cement is in a range from 0.01 to 0.05 by weight.

15 . A method of preparing a ductile self-cleaning cementitious composite, the method comprising:
mixing a hydraulic cement, water, wherein the ratio of water to the hydraulic cement is a range from 0.2 to 1 by weight; a plurality of fibers, wherein the average length of each fiber is in a range from 4 to 30 mm, wherein the ratio of the plurality of fibers to the hydraulic cement is in a range from 1 to 3% by volume; and a self-cleaning agent, wherein the ratio of the self-cleaning agent to the hydraulic cement is in a range from 0.01 to 1 by weight; and curing the mixture.

16 . The method of claim 15 , wherein the self-cleaning agent is selected from the group consisting of nanoparticles of titanium dioxide (TiO 2 ), zinc oxide (ZnO), iron (III) oxide (Fe 2 O 3 ), cadmium sulfide (CdS), zinc sulfide (ZnS), tungsten (VI) oxide (WO 3 ), copper (I) oxide (Cu 2 O), silver phosphate (Ag 3 PO 4 ), strontium titanate (SrTiO 3 ), barium titanate (BaTiO 3 ), calcium titanate (CaTiO 3 ), and a mixture thereof.

17 . The method of claim 16 , wherein the self-cleaning agent is TiO 2 nanoparticles.

18 . The method of any one of claims 15 to 17 , wherein the ratio of the self-cleaning agent to the hydraulic cement is in a range from 0.05 to 0.1 by weight.

19 . The method of claim 18 , wherein self-cleaning agent is TiO 2 nanoparticles and the ratio of TiO 2 nanoparticles to the hydraulic cement is 0.05 or 0.1 by weight.

20 . The method of any one of claims 15 to 19 , wherein the hydraulic cement is selected from the group consisting of Portland cement, blended Portland cement, expansive cement, rapid setting and hardening cement, calcium aluminate cement, magnesium phosphate, and a mixture thereof.

21 . The method of claim 20 , wherein the hydraulic cement comprises Type I white Portland cement.

22 . The method of any one of claims 15 to 21 , wherein the plurality of fibers are selected from a group consisting of polypropylene (PP) fibers, aromatic polyamide fibers, high modulus polyethylene (PE) fibers, polyvinyl alcohol (PVA) fibers, steel fibers, and a mixture thereof.

23 . The method of claim 22 , wherein the plurality of fibers are PVA fibers.

24 . The method of claim 23 , wherein the ratio of the plurality of PVA fibers to the hydraulic cement is 2% by volume.

25 . The method of any one of claims 15 to 24 , further comprising a viscosity control agent, wherein the ratio of viscosity control agent to the hydraulic cement is in a range from 0.001 to 0.05 by weight.

26 . The method of claim 25 , wherein the viscosity control agent comprises methylcellulose, polyvinyl alcohol, or starch.

27 . The method of any one of claims 15 to 26 , further comprising a water reducing agent, wherein the ratio of water reducing agent to the hydraulic cement is in a range from 0.005 to 0.07 by weight.

28 . The method of claim 27 , wherein the water reducing agent comprises a polycarboxylate-based superplasticizer and the ratio of the water reducing agent to the hydraulic cement is in a range from 0.01 to 0.05 by weight.

Assignees

• Univ Nanyang Tech

Inventors

• Yang En-Hua
• Zhao Aiqin

Classifications

• C04B28/34

  containing cold phosphate binders · CPC title

• C04B2111/2061

  Materials containing photocatalysts, e.g. TiO2, for avoiding staining by air pollutants or the like · CPC title

• C04B28/06

  Aluminous cements (monolithic refractories or refractory mortars C04B35/66) · CPC title

• C04B28/04 Primary

  Portland cements · CPC title