Chloride ion analysis in São Pedro Cathedral restoration mortar

Abstract

The pathological manifestations found in masonry structures in regions with a marine atmosphere have humidity and soluble salts as the main agents of deterioration of construction materials. Among the various techniques and materials used for the recovery of these structures, there is the execution of coatings with sanitation mortars. In Brazil there are still insufficient studies on new materials and constructive techniques related to the recovery of masonry with salinization pathologies. For the execution of the research, the east and west facades were identified as being the ones of action and in them seven critical points of humidity in the coating. Samples were taken to analyze the percentage of retention of chloride ions using a potentiometer with a silver electrode. In the samples, the condition of integrity of the original components of the sanitation mortar was verified from the observation of the crystalline structures, by X-ray diffraction (DRX), and the presence of the constituent elements, by X-ray fluorescence. The results showed that the proposed formulation for the new sanitation mortar fulfilled its protective function by retaining chloride ions in its pores and, also, that its original constituents have not been degraded so far.

Keywords
Historic buildings; Saline environment; Sanitation mortar; Retention of chloride ions