The Development of Photoactive Admixtures for Concrete and Cement-Based Plaster Finishes, to Create Self-Cleaning Surfaces

Abstract

This article presents research and development on innovative photoactive admixtures for concrete and cement-based plasters for the finishing of concrete surfaces finished this year. The goal of the development was to provide the resulting surfaces of these newly developed materials with a self-cleaning ability stemming from photocatalytic reaction during exposure to UV radiation. The specific function of all these products is based on the photocatalytic oxidative mineralization of all organic structures present on the surface, i.e., their gradual transformation into the final simple inorganic compounds, which are carbon dioxide, water and the corresponding mineral acids. This research and development was carried out as part of a project supported by the Czech Ministry of Industry and Trade, in the TRIO programme; and in cooperation of BETOSAN s.r.o., the Technical University of Liberec, the Institute of Inorganic Chemistry of the Czech Academy of Sciences and the J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences. The first type of developed material is a photocatalytically active admixture in powder form, allowing the preparation of concrete surfaces with photocatalytic properties. The second type of developed material is a photocatalytically active cement-based plaster, intended primarily for application to a concrete substrate. Two final versions of both materials were developed. In the case of the plaster this means preparation of two colour variants, specifically white and grey. For the powder concrete admixture two types with different application procedures were developed. This means one version of admixture mixed throughout the entire volume of the concrete and second variant applied only in the surface layer of the concrete. We anticipate mainly exterior applications on the self-cleaning outer shell of buildings, as well as treatment of the surface layer of various structures such as bridges, noise barriers, traffic barriers and tunnels. The developed materials can also be used in interiors under specific conditions, with anticipated uses in the health care and food processing industries.