Influence of carbon nanotubes on steel–concrete bond strength
In this study, the bond strength between steel and concrete reinforced with multi-walled carbon nanotubes (CNTs) is analysed. To this end, pull-out tests were carried out for concretes with incorporation of 0.05–0.1% of different types of functionalized and unfunctionalized CNTs with distinct aspect ratios and dispersion techniques. The results showed that CNTs can improve both compressive strength and steel–concrete bond up to 21% and 14% respectively, as compared to plain concrete. The highest compressive strength was found in concrete with higher amounts of lower aspect ratio CNTs, while the best steel–concrete bond performance was attained for concrete with lower amounts of higher aspect ratio CNTs. CNTs were effective to retain the crack propagation, increasing the bonding stiffness and reducing the deformation of concrete consoles between steel ribs. CNTs of higher aspect ratio could better contribute with their microcrack bridging effect. Microscopic analysis confirmed the adequate dispersion and microcrack bridging provided by CNTs, delaying the macrocrack propagation within the aggregate–paste and steel–concrete interfacial transition zones.
Publisher URL: https://link.springer.com/article/10.1617/s11527-018-1279-8