Functionalizations of surfaces of concrete

The functionalization of concrete surfaces is a fast-growing field, not only because of the ease with which this construction material can be produced, but also because of the large number of surfaces available in urban environments. This article takes stock of the various functionalities already available on the market or currently being developed, which make it possible to envisage other properties for this construction material beyond its intrinsic properties of structural strength and durability. After a reminder of the intrinsic variability of concrete surface composition, we list the various parameters and processes (formwork, stripping agents, post-treatments) impacting the appearance of concrete. We then turn our attention to coloring, considering the possibility of coloring concrete not in the mass, but via a transfer of pigments to its surface. This is followed by a presentation of the levers that can be used to influence the interaction of water with concrete (i.e. how to make it less permeable, superhydrophilic or, on the contrary, superhydrophobic). Interactions between gaseous pollutants and concrete surfaces are then explained, by studying the influence of two types of functionalization aimed at improving air quality: the incorporation of photo-catalytic pigments, or activated carbons, within concrete. Finally, the suitability of concrete surfaces for photovoltaic energy production is presented by describing two distinct processes for functionalizing building facades: the bonding of solar cells to cladding panels, and the direct deposition of thin photovoltaic layers on concrete under partial vacuum.

At the end of the article, readers will find a glossary and table of acronyms and symbols.