Evaluation of the mechanical properties on fracture of cement pastes with addition of graphene oxide

ABSTRACT

Cement-based composite materials, including cement paste, mortar and concrete, are the most commonly used materials in civil construction. However, its brittle nature, high hardness, low tensile strength and propensity to cracking are key factors that compromise durability and result in high maintenance costs for structures. Reinforcement materials such as steel bars, steel fibers, carbon fibers, glass fibers and polymers have been extensively applied to concrete in recent years. Although these materials can greatly improve the toughness of concrete, solving well the defects that occur in the micro scale inherent to cementitious materials, the fractures in these materials persist. Nanomaterials (such as nanosilica, carbon nanotubes and graphene derivatives) can act as a complement to traditional fibers, further reinforcing fibrous cementitious materials, through mechanisms that restrict the initiation and propagation of cracks at the nanometer scale, as well as providing an extremely high specific surface area for interaction with cement hydration products. Among the nanomaterials, graphene oxide (GO) has an enormous potential for application in cementitious composites. In this work, tests were carried out with the addition of GO produced and patented at CTNano/UFMG in cement pastes class CP-III-RS-40. The objective was to evaluate the mechanical properties of cement pastes with the addition of GO, at the levels of 0.03% and 0.05%. Among the addition levels analyzed, the content of 0.05%GO allowed to obtain the best results at 28 days of curing. Increases of 19.40%, 16.86%, 27.37% and 21.55% were obtained in the modulus of elasticity, flexural tensile strength, fracture toughness and fracture energy, respectively. In view of these results, it can be inferred that GO has the potential to be applied in civil construction, aiming the improvement of the mechanical properties and fracture parameters of cement pastes.

Keywords
Cement composites; Nanomaterials; Graphene oxide; Mechanical properties