Experimental study of the freeze and thaw effects on the mechanical behaviour of self-compacting high-performance fibre-reinforced concrete containing active powders and/or Carbon NanoTubes

ABSTRACT In this paper, the mechanical properties of High-performance fiber reinforced cementitious composites containing active powders, such as metakaolin and fly ash, with a combination of carbon nanotubes (CNTs) and steel fibers have been investigated. The presence of active powders and their combination with micro-silica, increase the physical and mechanical properties of fibre concrete. Subsequently, by adding CNTs, the precise microstructural properties of concrete before and after 300 cycles of thawing-freezing, according to the ASTMC666 standard by scanning electron microscope (SEM) have been analysed. The results reveal that by adding active powders and steel fibres in the concrete, the volume of cavities reduces, and the bonding between concrete components increases. moreover, the addition of functionalised CNTs creates the crack bridge and prevents the propagation and growth of micro-cracks. This leads to increasing the mechanical properties of concrete before the cycles and decreasing the strength loss (bendingand compressive) after thawing-freezing cycles.