Cement reinforced with high concentrations of mechanically dispersed multiwalled carbon nanotubes and carbon nanofibers

Patent metadata

Field	Value
Publication number	US-11851374-B2
Application number	US-202117376426-A
Country	US
Kind code	B2
Filing date	Jul 15, 2021
Priority date	Jul 15, 2020
Publication date	Dec 26, 2023
Grant date	Dec 26, 2023

Abstract

Methods for the dispersion and synthesis of multi-walled carbon nanotube-cement composites with high concentrations of multi-walled carbon nanotubes that do not require chemical dispersion aids or dispersion-enhancing chemical surface functionalization are provided. Also provided are multi-walled carbon nanotube-cement composites made using the methods. Methods for the dispersion and synthesis of carbon nanofiber-cement composites with high concentrations of carbon nanofibers that do not require chemical dispersion aids or dispersion-enhancing chemical surface functionalization are further provided. Also provided are carbon nanofiber-cement composites made using the methods.

First claim

What is claimed is:

1. A cement composite comprising:
Portland cement; and
multiwalled carbon nanotubes that are free of dispersion-enhancing chemical surface functionalization and are present at a concentration in the range from 0.2 wt % to 1.0 wt %, based on the total weight of the Portland cement and the multiwalled carbon nanotubes, wherein:
the cement composite is free of dispersing aids;
the cement composite has a gel porosity in the range from 0.15 to 0.20 and a capillary porosity of less than 0.1;
the cement composite has a volume fraction of high-density calcium-silicate-hydrates in the range from 0.3 to 0.6; and
the cement composite has a Young' modulus in the range from 15 GPa to 50 GPa.

2. The cement composite of claim 1 consisting essentially of the Portland cement and the multiwalled carbon nanotubes.

3. The cement composite of claim 1 consisting only of the Portland cement and the multiwalled carbon nanotubes.

4. The cement composite of claim 1 , wherein the multiwalled carbon nanotubes have an average diameter in the range from 5 nm to 50 nm and an average length in the range from 1 μm to 50 μm.

5. The cement composite of claim 1 having a volume fraction of low-density calcium-silicate-hydrates in the range from 0.01 to 0.15 and a volume fraction of calcium hydroxide in the range from 0.25 to 0.40.

6. The cement composite of claim 1 having a concentration of multiwalled carbon nanotubes in the range from 0.2 wt % to 0.5 wt. %, based on the total weight of the Portland cement and the multiwalled carbon nanotubes.

7. The cement composite of claim 6 having a volume fraction of high-density calcium-silicate-hydrates in the range from 0.5 to 0.6.

8. The cement composite of claim 7 having a fracture toughness in the range from 0.70 MPa√{square root over (m)} to 0.80 MPa√{square root over (m)}.

9. The cement composite of claim 5 having a concentration of multiwalled carbon nanotubes in the range from 0.2 wt % to 0.5 wt. %, based on the total weight of the Portland cement and the multiwalled carbon nanotubes, a volume fraction of high-density calcium-silicate-hydrates in the range from 0.5 to 0.6, and a fracture toughness in the range from 0.70 MPa√{square root over (m)} to 0.80 MPa√{square root over (m)}.

10. The cement composite of claim 1 , wherein gel pores having a pore size of 2 nm or smaller make up at least half of the total porosity.

11. A cement composite comprising:
Portland cement; and
carbon nanofibers that are free of dispersion-enhancing chemical surface functionalization and are present at a concentration in the range from 0.1 wt % to 0.5 wt %, based on the total weight of the Portland cement and the carbon nanofibers, wherein:
the cement composite is free of dispersing aids;
the cement composite has a gel porosity in the range from 0.16 to 0.20 and a capillary porosity of less than 0.1;
the cement composite has a volume fraction of high-density calcium-silicate-hydrates in the range from 0.65 to 0.75; and
the cement composite has a Young' modulus in the range from 30 GPa to 40 GPa.

12. The cement composite of claim 11 consisting essentially of the Portland cement and the carbon nanofibers.

13. The cement composite of claim 11 consisting only of the Portland cement and the carbon nanofibers.

14. The cement composite of claim 11 , wherein the carbon nanofibers have an average diameter in the range from 70 nm to 500 nm and an average length in the range from 50 μm to 200 μm.

15. The cement composite of claim 11 having a volume fraction of low-density calcium-silicate-hydrates in the range from 0.005 to 0.05, a volume fraction of ultrahigh-density calcium-silicate-hydrates in the range from 0.05 to 0.20, and a volume fraction of clinker in the range from 0.05 to 0.15.

16. The cement composite of claim 15 having a fracture toughness in the range from 0.70 MPa√{square root over (m)} to 0.80 MPa√{square root over (m)}.

17. The cement composite of claim 11 , wherein gel pores having a pore size of 2 nm or smaller make up at least half of the total porosity.

Assignees

• Univ Northwestern

Inventors

• Akono Ange-Therese
• Chen Jiaxin

Classifications

• C04B28/04 Primary

  Portland cements · CPC title

• C04B14/026

  of particular shape, e.g. nanotubes · CPC title

• C04B14/386

  Carbon (carbon nanotubes C04B14/026) · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title