Interacción entre comportamiento hídrico, sales superficiales y eficacia de tratamientos de control de biodeterioro en fachadas de ladrillo cerámico en ambiente urbano húmedo

Abstract

This applied experimental study, conducted in Bogotá D.C., Colombia, analyzes the behavior of ceramic bricks subjected to biodeterioration under high humidity conditions and evaluates the effectiveness of a 10% benzalkonium chloride (Benzalkonium Chloride) treatment on the substrate. Two complementary methodologies are employed: (i) quantification of biodeterioration through digital image processing, using chromatic segmentation and pixel-by-pixel analysis to determine the percentage of coverage and its temporal variation post-treatment; and (ii) physicochemical characterization of the material through capillary absorption tests, pH analysis, soluble salt content measurement, and scanning electron microscopy with EDS analysis. The results showed a progressive reduction of the active biofilm at both concentrations evaluated, with a greater response in the sample treated with 10% benzalkonium chloride, which achieved an effectiveness of 91.59% after 92 hours of follow-up. From a physicochemical standpoint, the pH showed little variation, decreasing from 9.61 in the untreated sample to 9.35 in the treated sample, while the soluble salt content increased from 0.09% to 0.21%. The capillary absorption test revealed an approximate 61% reduction in initial water absorption, although complete waterproofing of the material was not evident. SEM-EDS analysis identified morphological alterations in the biofilm, surface residues associated with the treatment, and an increase in carbon, oxygen, and chlorine, consistent with the surface persistence of the BAC. It is concluded that the 10% BAC showed high efficacy in reducing the active biofilm under the evaluated conditions; however, its performance should be interpreted holistically, considering biological efficacy, the modification of water behavior, the increase in soluble salts, and the surface interaction with the ceramic matrix.