Efeitos da adição de óxido de grafeno em argamassas de reparo estrutural submetidas à carbonatação

Abstract

Graphene and its derivatives have shown great results in the improvement of cementitious composites. Graphene oxide (GO) stands out among these derivatives, with its large specific surface area, high mechanical strength, and good chemical stability. Mixed with Portland Cement, its layers physically can contribute to a greater mechanical strength of the final composite. In addition, according to specific literature, GO can influence the cement hydration process, acting like a nucleator of the cement hydration products and refining the pore structure of the hydrated cement. These characteristics are very desirable in a structural repair material for reinforced concrete since the reduction of the penetration of aggressive agents in the cementitious matrix avoids its carbonation and, therefore, the triggering of the corrosion process of the steel bars. This work studied the effect of GO in structural repair mortars (grout) subjected to carbonation. The grout was developed with Portland Cement, stone powder, sand and GO at three different rates (0.00 %, 0.03 %, and 0.10 % to the cement mass). Workability tests in the fresh state (using a flow table) were carried out. The tensile and compressive strength of the material in the hardened state and the advance of the carbonation front, in an accelerated carbonation process, were also evaluated. It was verified that the mortar with 0.03% of GO presented the best results in terms of tensile strength and carbonation depth. It was also noted difficulty in the homogeneous molding of the samples with the addition of OG in the content of 0.1 %, resulting in a reduction in their compressive strength and greater variability of their results. Thus, considering the positive results of the tests, it is understood that graphene oxide is a promising material that can contribute to the improvement of cementitious materials.