Tensile and Shear Response of Concrete with Nano-Materials

• Pierre van Tonder

  Civil Engineering Science, Faculty of Engineering and the Built Environment, University of Johannesburg, Auckland Park, Johannesburg, South Africa

In concrete members that are subjected to bending, such as beams and slabs, the tensile and shear strength of concrete is an important property. Over the years, a lot of work has been done to try and improve these properties. It has been found that concrete’s biggest shortcoming is its weak tensile and shear strength. To improve the tensile and shear strength, different types of reinforcement, such as round bars or fibres, have been added to the concrete. The interfacial transition zone’s strength and density are improved, due to the small size and tensile strength of the incorporated nano-materials.  The tensile and shear strength of concrete is the focus of this investigation with the incorporation of multi-walled carbon nano-tubes (MWCNTs) and graphite nano-fibres (GNFs) into the concrete mix. One of the limitations to the use of nano-materials in concrete mixes is the tendency of the carbon nanotubes to adhere to one another due to the formation of balls and the strong van der Waals interaction forces. Additionally, there is a lack of cohesion between the nanotubes, which can be attributed to the cost of nano-materials. However, cohesion can be increased by using gum arabic and a process called functionalization, which helps to improve the dispersion and purification process of the nano-materials.

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