Abstract
The use of new reinforcing materials like carbon nanofibers (CNFs) makes it possible to produce cement based nanocomposites with revolutionary properties. However, in order to take advantage of the CNF's excellent reinforcing efficiency it is necessary to achieve a uniform distribution in the matrix. In this work, nanofiber cementitious composites were produced containing CNFs at an amount of 0.048 wt.% of cement. To achieve good dispersion of the CNFs, a method utilizing a surfactant and ultrasonic processing, was employed. The method was optimized using two parameters: the effect of ultrasonic energy and the effect of surfactant to CNF (SFC/CNF) ratio. Initially, the SFC/CNF ratio on the dispersion of two types of CNFs, one subjected to a new special debulking method and one with minimal debulking process, was investigated. An ultrasonic energy of 2800 kJ/l and a SFC/CNF ratio close to 4.0 was found to be optimal for effective dispersion. Following these values, cement based nanocomposites reinforced with four types of CNFs, subjected to different debulking processes and having different morphology, were produced. Their nanostructure was studied using scanning electron microscopy (SEM). Their mechanical performance was evaluated using fracture mechanics tests. All four CNFs were found to control nanoscale cracking. As a result, both the flexural strength and the stiffness of the nanocomposites were significantly improved. Furthermore, the reinforcing efficiency of the CNFs in the cementitious matrix was shown to depend on the debulking procedure: at later ages, the use of the CNF subjected to the special debulking process was found to be more efficient in improving the mechanical performance of the nanocomposites.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 25-32 |
| Number of pages | 8 |
| Journal | Cement and Concrete Composites |
| Volume | 36 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 2013 |
Funding
The authors would like to acknowledge the financial support from the Infrastructure Technology Institute at Northwestern University under Grant DTRT06-G-0015/M1 . The authors would also like to thank Applied Sciences Inc for supplying the carbon nanofibers. The scanning electron microscopy experiments were carried out in the EPIC facility of NUANCE center at Northwestern University.
Keywords
- Carbon nanofibers
- Dispersion
- Mechanical properties
- Nanocomposites
- Scanning electron microscopy
ASJC Scopus subject areas
- Building and Construction
- General Materials Science