Diagnosis of Pathological Manifestations and Characterization of the Mortar Coating from the Facades of Historical Buildings in Porto Alegre - Brazil: A Case Study of Chateau and Observatorio Astronomico

This article presents the diagnosis of pathological manifestations on the mortar coating from the facades of two historical buildings of scientific and social importance in Porto Alegre, Brazil. Documental investigation, visual survey, percussion and thermography tests, mapping of damages, and characterization of the coatings were performed. Coatings were characterized by determining the binder:aggregate proportion and the aggregate particle size distribution; X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and qualitative test of soluble salts were performed. The damage maps present the extension of anomalies, like detachments and areas with moisture, which were located with support of thermography results. Mortar samples extracted from the buildings indicated binder:aggregate proportions, in dry mass, ranging from 1:1 to 1:2.7. In the binder, it was verified mainly the existence of calcite and quartz through XRD; with XRF, magnesium oxide was additionally verified and calcite was also found with TGA. Chlorides and sulfates were identified by XRF and test of soluble salts. The fineness module and the particle size distribution of siliceous aggregates from different samples were similar.