The influence of carbon nanotubes on the fracture energy, flexural and tensile behavior of cement based composites

Carbon nanotubes (CNTs) can be incorporated into cement-based materials in order to nucleate hydration products, enhance mechanical behavior, control micro crack formation and reduce deformation. Given that, the present paper investigates the mechanical behavior of a cement paste system reinforced with 0.05% and 0.10% of CNTs dispersed in a non-aqueous media of isopropanol on the surface of cement particles. Even though compromising the consistency and affecting the setting time, if well dispersed and properly bonded to the cement hydration products, the CNTs can act as nucleation site of cement hydration products and improve the mechanical properties of a cement paste system. Three-point bending tests in notched specimens and direct tensile tests were carried out using the manufactured material. The presence of CNTs on the cement paste resulted in a 90% of gain in fracture energy, 46% of flexural strength, and 47% tensile strength with addition of up to 0.10% of CNTs. Through SEM observation it is possible to affirm that the dispersion process was effective and CNTs acted as nucleation sites of cement hydration products, allowing its use as a reinforcement material. (C) 2019 Elsevier Ltd. All rights reserved.