Abstract
Carbon nanotubes (CNTs) have been used as reinforcing material for many different matrices. There are many studies in the literature reporting that reinforcement of CNTs into concrete matrix improved the properties of the concrete. In this study, first unmodified CNTs were reinforced to concrete and it was seen that there were partial decreases in strength despite the increasing rate of CNTs. Thereon, the surfaces of CNTs to be used as reinforcing material were modified with water-soluble surfactants (Polyvinyl alcohol-PVA, Polyvinylpyrrolidone-PVP, Poly (ethylene glycol)-PEG, Dodecylamine-DDA) and reinforced with concrete. In previous studies, many different surfactants were tried to functionalise the surfaces of CNTs. However, in this study, water-soluble polymeric surfactants were preferred without the need for an additional process in order to modify the surfaces of CNTs. In addition, the effect of the surfactants used on the mechanical properties of concrete was examined comparatively. Although the amount of CNTs reinforcement is very low like 0.05 wt%, the increase in strength was seen to be above 60%. The highest strength values were obtained in the sample in which PVA was used as surfactant. Through the surfactants used, bundles of CNTs were fully opened and distributed homogeneously into the concrete matrix, and all of the CNTs were embedded into the matrix by getting wet by the matrix. In the real application, it will be possible to use new generation concretes with higher strength and lighter weight by providing the ease of reinforcing CNTs to the concrete matrix.