Insight into dynamic compressive response of carbon nanotube/carbon fiber-reinforced concrete

Abstract

The dynamic compressive properties of concrete reinforced with the carbon nanotubes (CNTs) and carbon fibers (CFs) were investigated in this paper. For both single and hybrid addition, the CNTs and CFs enhanced the dynamic compressive strength of the concrete, but the hybrid addition showed a higher enhancement effect. Hybrid CNTs and CFs were more conducive to improve the strain-rate effect of the dynamic compressive strength, and when the content of hybrid CNTs and CFs was constant, a higher proportion of CNTs led to a more significant improvement. However, the addition of CNTs alone reduced the strain-rate effect. The addition of CNTs increased the content of hexagonal prismatic Ca(OH)2, the proportions of gel pores and harmless capillaries, and decreased the porosity of the concrete, thus enhancing the dynamic compressive strength of the concrete. The addition of CFs increased the porosity of the concrete and the probability of large pores. But the crack-inhibition action of the CFs still led to the increase of the dynamic compressive strength. The hybrid synergistic effect of CNTs and CFs was more conducive to enhance the dynamic compressive strength and its strain-rate effect, and also to enhance the impact resistance of the concrete.