Fair-faced concrete and anti-graffiti protection

Abstract

Fair-faced concrete, a design option in public and private buildings, works of art, common structures like bridges and retaing walls, largely built in the twentieth century is susceptible to attacks by graffiti. Durability of concrete depends on the composition and characteristics of the surface, whereby it is essential to study the effects of anti-graffiti protection systems on concrete durability and to adopt the appropriate methodology in order to preserve the integrity and authenticity of this heritage. Concrete is a porous material sometimes deteriorated over the years. The interactions between the inks and the substrate as well as the removal methods sometimes may deteriorate or alter the concrete surface, especially if it is necessary to repeat the removal process. Anti-graffiti products form a protective barrier on the concrete surface, hindering the adhesion of paints or preventing its penetration into the pores of the concrete, which facilitates graffiti paint removal. Thus, an experimental program was developed to analyze changes in durability indicators and surface properties related to concrete deterioration. The following possibilities were studied: (i) concrete without protection before and after application of the spray paint, (ii) concrete with protection before and after application of the spray paint and (iii) after paint removal. The concrete durability indicators studied were water absorption by capillarity and immersion and penetration of CO2. Analysis by stereo binocular microscope, scanning electron microscope and energy dispersive x-ray spectroscopy were performed. The results obtained show that the applied graffiti, the graffiti protection and the graffiti removal affect surface characteristics.