Effects of nanoparticles on the mechanical behaviour of fibre-reinforced concrete

The tensile behaviour of concrete corresponds to approximately 10% of its compressive strength. This limitation can be overcome with the incorporation of short fibres in concrete. Adding fibres to concrete increases its direct tensile strength, flexural tensile strength, toughness and ductility, and improves its crack resistance and ability to absorb energy after cracking. This paper focuses on the effect of the incorporation of carbon nanotubes (CNTs) in concrete reinforced with steel fibres on the flexural strength, toughness and residual strength of the concrete. For this purpose, three-point flexural tests were performed on prismatic-notched specimens. Concretes were manufactured with 1% steel fibres and three different quantities of nanoparticles (0.05, 0.10 and 0.15%). Compressive strength tests were also carried out. The fibre-reinforced concrete with the lowest content of CNTs (0.05%) led to an increase in maximum flexural strength by 9% when compared with the addition of only steel fibre and by more than 48% for the concrete without fibres. In addition, the residual strength also increased, leading to greater rigidity, toughness and load-bearing capacity.