Desenvolvimento de um composto cimentício fotocatalítico com adições de g-C3N4 e grafeno

Abstract

Inefficiency in terms of durability and maintenance in buildings causes a large consumption of materials. Therefore, the development of advanced materials is necessary to be able to reverse this situation. In this context, photocatalysis is seen as one of the most promising “green alternatives”. In addition to contribute to a better air quality through the decomposition of contaminants, this process can still be explored in construction materials to promote self-cleaning properties. Therefore, the main objectives of this research are: 1) verify the efficiency of the photocatalytic activity of a cement paste manufactured with the combination of two nanomaterials, one of them still few studied in cementitious matrices: the g-C3N4; 2) check the influence of the nanomaterials on the rheological, mechanical, and photocatalytic properties of cement pastes. Considering a possible synergy between the g-C3N4 and graphene materials and aiming to improve the mechanical strength, graphene was also added to the cementitious matrix. The composite materials were then characterized and evaluated in the fresh and hardened states. Regarding the mechanical strength, the greatest gains were obtained with pastes containing graphene, reaching a 17.7% increase in compressive strength and a 13% increase in flexural tensile strength. The graphitic carbon nitride did not promote significant mechanical changes when incorporated at intermediate or high levels. On the other hand, from a rheological point of view, the g-C3N4 was the most responsible for large changes in the fresh state. To determine the photocatalytic activity, the removal rate of methylene blue dye in water as a function of the time was evaluated. The samples with the highest percentage of g-C3N4, with or without graphene, were the ones showing the best results for this parameter, reaching approximately 60% of dye removal. This research indicates a significant trend for the practical application of g-C3N4 and graphene to produce cementitious composite materials with potentially enhanced photocatalytic capabilities.