Influence of carbon nanotubes on the performance of concrete and fiber reinforced concrete (FRC)

ABSTRACT

Concrete is a material with a high frequency of use in Brazilian constructions and in buildings in countries around the world. Factors such as reduced material costs, high research volume and high resistance, contributed to the wide use of concrete as a building material. However, concrete has low tensile strength, cracking easily and has a low deformation capacity. Fiber reinforced concrete (FRC) was developed in the 1960s and is a material that presents a good mechanical response in terms of residual strength after cracking of the matrix and consequently a more ductile behavior than concrete without fibers. The effect of adding fibers to the concrete is restricted only to the post-cracking phase of the loading process. The fibers have no effect on the behavior that precedes the peak load. Recent advances in nanotechnology have enable the production of nanoparticles, in particular, carbon nanotubes. The nanoparticles can be used to reinforce the cement matrix to act at the level of its nanostructure. The proposed research studies the behavior of concretes containing the incorporation of carbon nanotubes and also of steel fiber reinforced concrete (SFRC) with the addition of carbon nanotubes. The research aims to evaluate improvements in the response of concretes and SFRC, based on the incorporation of carbon nanoparticles. Compression and flexural tests were performed on notched prismatic specimens. It has been found that nanotubes reduce the absorption of water and improve the mobility of mixtures (concrete and SFRC) in the fresh state. Increases in axial compression strength and flexural strengths of concrete and SFRC materials were also observed when adding carbono nanotubes.

Keywords
Concrete; SFRC; Carbon nanotubes