Influence of the chemical composition of mortars on algal biofouling

The main cause of building-facade biodeterioration is the growth of microorganisms. The state of surface is among parameters which affects the most biofouling kinetics. The main objective of this study was to highlight the influence of mortar chemistry and its physical properties on algal growth. The green algae Klebsormidium flaccidum was chosen for this work because of its representativeness. In order to characterize the influence of the mortar chemistry on biofouling, Portland cement (CEMI) and aluminate cement (CAC) were used. The biofouling kinetics was followed on samples tested in a laboratory bench, where the mortar specimens were exposed to a sprinkling of algal suspension. The algal growth was daily monitored by image analysis. The colonization rate was given by the ratio of colonized area to the total surface. In our case, the surface roughness does not seem to affect the algal colonization. The experimental method highlights that surface pH and chemistry of cement used in mortar formulations have an influence on algal fouling. In fact, the colonization kinetics of CAC mortars is lower than that of CEMI mortars