Highly concentrated nano-reinforcement suspensions for cementitious materials and method of reinforcing such materials

1. A method for producing reinforced cement-based materials comprising a concentrated suspension of multiwall carbon nanotubes (MWCNTs), comprising the steps of:

(a) providing a first solution, said first solution comprising water and surfactant;

(b) creating a second solution by dispersing said MWCNTs in said first solution, wherein said second solution has a first UV-vis-NIR absorbance value, and wherein the concentration of MWCNTs in said second solution is less than or equal to 0.16 weight %;

(c) creating a third solution by ultracentrifuging said second solution,

wherein said third solution comprises a concentrated portion and a non-concentrated portion,

wherein said concentrated portion has a second UV-vis-NIR absorbance value, and said second UV-Vis-NIR absorbance value is between 3.13 and 4.87 times said first UV-vis-NIR absorbance value; and

(d) removing said non-concentrated portion from said third solution to create said concentrated suspension of MWCNTs.

2. The method of claim 1 wherein dispersing occurs by ultrasonication.

3. The method of claim 1 wherein ultracentrifuging utilizes a swing bucket rotor.

4. The method of claim 1 wherein ultracentrifuging utilizes a fixed angle rotor.

5. The method of claim 1 wherein said concentrated portion is positioned below said non-concentrated portion.

6. The method of claim 1 further comprising the step of adding water to said concentrated suspension of MWCNTs to create a fourth solution.

7. The method of claim 6 wherein the concentration of MWCNTs in said fourth solution is less than or equal to 0.16 weight %.

8. The method of claim 1 wherein said concentrated suspension of MWCNTs comprises non-bundled MWCNTs.

9. The method of claim 1 wherein said MWCNTs are non-chemically functionalized.