Civil and Environmental Engineering
 
 
Nano-Engineering and Multiscale Performance of Cement-Based Composites

Concrete is a material whose basic building block exists on the scale of nanometers.

Nano-engineering of concrete is a quickly emerging field. It encompasses the incorporation of nano-sized additives (e.g., nanoparticles and nanotubes) to control material behavior and add novel properties and the grafting of molecules onto cement particles, cement phases, aggregates, and additives (including nano-sized additives) in order to provide surface functionality, which can be adjusted to promote specific interfacial interactions.

  A Complex Multiscale Material

 

Our group investigates the application of carbon nanofibers (CNFs) as a nano-reinforcement to replace steel rebar, one of the main causes of concrete degradation.

 

Rebar Nano rebar

 

Key aspects in translating the properties of CNFs to cement composites at a practical length scale include proper dispersion of the CNFs in the cement paste and the degree of interfacial interaction between the CNFs and the surrounding matrix. This requires understanding the microstructure and nature of assemblages of cement phases and CNFs in addition to evaluating the mechanical performance of the CNF/cement composite.

Our group studies the relationship between paste microstructure, composite engineering properties, and CNF dispersion. We explore a number of methods to improve disaggregation and dispersion of the CNFs and to activate the graphite surface for enhancing interfacial interaction through surface functionalization and coatings, optimal physical blending, and/or the use of surfactants and other admixtures.

 

Selected References

"Performance of carbon nanofibers/cementitious composites with a high-range water-reducer," C. Gay and F. Sanchez. Transportation Research Record: Journal of the Transportation Research Board, In press, October 2009. View Abstract.

"Carbon nanofibre/cement composites: challenges and promises as structural materials," F. Sanchez. International Journal of Materials and Structural Integrity, 3(2-3), 217-226, 2009. [Special issue on Nanotechnology for Structural Materials; Guest Editors: M.R. Taha and M. Al-Haik]. View Abstract.

"Microstructure and macroscopic properties of hybrid carbon nanofibers/silica fume cement composites," F. Sanchez and C. Ince. Composites Science and Technology, 69(7-8), 1310-1318, 2009. View Abstract.