Photocatalytic Concrete Blocks Nanomodified with Zinc Oxide for Paving: Mechanical Performance and Microstructural Characteristics

Abstract

Abstract Concrete block pavement is considered an ideal substrate for the application of photocatalyst materials. In the paving area, titanium dioxide (TiO2) has been the most widely used semiconductor because of its properties. However, zinc oxide (ZnO) has been recently used as an alternative material to TiO2 in heterogeneous photocatalysis, being applied mainly for the treatment of liquid effluents. In this perspective, the aim of this study was to evaluate the capacity of concrete blocks nanomodified with ZnO in the degradation of nitrogen oxides (NOx) as well as the impact of the nanomaterial on the mechanical properties and microstructural characteristics of concretes. For this purpose, concretes were produced with ZnO incorporation of 3 %, 6 %, and 9 %, being submitted to photocatalytic tests, simple compressive strength, flexural strength, and dynamic Young’s modulus, as well as mercury intrusion porosimetry tests and image evaluations using scanning electron microscopy. Together, evaluation of the influence of nano-ZnO on cement paste hydration reactions was carried out. It could be concluded that the addition of ZnO to concrete provides photooxidative capacity to the material; however, it impairs the mechanical performance and the development of the cementitious matrix microstructure.