Influência da adição de g-C3N4 nas propriedades mecânicas e de durabilidade de argamassas estruturais

Abstract

Indirectly, the construction industry contributes on a large scale to atmospheric pollution through the high consumption of cement, since the production of clinker, the main raw material for cement, generates significant emissions of greenhouse gases. Although Portland cement is widely used in composites and has high compressive strength, its tensile and flexural strength values are low, which makes it fragile and with reduced durability, contributing to the formation of cracks in structures and, consequently, allowing deformations that can lead to the penetration of deleterious agents. In this context, one of the solutions that have been highlighted in civil engineering is the development of innovative, sustainable and intelligent materials, through the addition of nanomaterials in the composition of mortars, aiming to improve microstructural properties. Among the nanomaterials with evidence of structural contribution, graphitic carbon nitride (g-C3N4) has been proven to be an interesting alternative, as it has a graphene-like carbon-based structure, in addition to exhibiting high chemical stability and excellent electronic and optical properties. The present study verified the influence of g-C3N4, with 0.25%, 0.50% and 1.0% by the content of cement, on the physical and chemical properties of structural mortars. However, it is common for nanostructures to present nucleation effects, low dispersion and homogenization, which can be reduced by the insertion of functional groups. For this, the hydroxylation of the surface of this nanomaterial was performed, using hydrogen peroxide (H2O2) and ultrasonic treatment. The functionalization product was incorporated into the mortar with a content of 1.0% by the content of cement. The analyzes of the mechanical strengths at 28 days reveal an increase of 16.0% in axial compression and 18.3% in flexural tensile strength between the reference sample and the sample with 1.0% exfoliated g-C3N4, while for the functionalized product this increase was subtle in compression (5.6%) and by 25.6% in flexural tensile strength. In general, both materials were able to improve the mechanical performance of the mortar in different ways, and function as mechanical reinforcement for the development of more resistant and less robust structures.