Durability of multi-walled carbon nanotube reinforced concrete

In this study the durability of concrete reinforced with different types of multi-walled carbon nanotubes (CNTs) is analysed. One type of acid treated CNTs and two types of pristine CNTs with distinct aspect ratios were analysed. Common structural concrete with various w/c ratios were produced and characterized regarding immersion and capillary water absorption and carbonation and chloride penetration resistance. Results show the potential of CNTs contribution to the enhancement of mechanical and durability properties of concrete, regardless of the type of CNTs and w/c ratio. The incorporation of 0.05-0.1% CNTs, by weight of cement, improved mechanical strength and durability properties up to 21% and 25%, respectively. The incorporation of CNTs was more effective when concrete was subjected to cracking conditions. In general, the best performance was found in concrete with higher amounts of CNTs of lower aspect ratio. Functionalized CNTs showed lower to similar behaviour to pristine CNTs of identical aspect ratio. The crack bridging and nucleation effect provided by CNTs was confirmed by SEM and thermogravimetric analysis.