Diagnosis of Pathological Manifestations and Characterization of the Mortar Coating from the Facades of Historical Buildings in Porto Alegre — Brazil: A Case Study of Château and Observatório Astronômico

ABSTRACT

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.

KEYWORDS:

• Characterization
• diagnosis
• facades
• historical buildings
• mortar coating
• pathological manifestations
• Porto Alegre

Acknowledgments

The authors appreciate the financial support of CNPq (Conselho Nacional de Desenvolvimento Tecnológico) and CAPES (Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), and the support of LAMTAC (Laboratório de Materiais e Tecnologia do Ambiente Construído), LACER (Laboratório de Materiais Cerâmicos), LAMAT (Laboratório Multiusuário de Análise Térmica), PPGCI (Programa de Pós-Graduação em Engenharia Civil: Construção e Infraestrutura) and UFRGS (Universidade Federal do Rio Grande do Sul).

Notes

¹ Inventário do Patrimônio Cultural de Bens Imóveis, Categoria Estruturação (Cultural Heritage Inventory), published in Porto Alegre Official Gazette, of March 07, 2008 (Porto Alegre 2008).

² State law nº 11.525 of September 15, 2000 (Rio Grande do Sul 2000).

³ Livro do Tombo Histórico (Heritage List): Registration nº 556, of 06/19/2000 (IPHAN (Instituto do Patrimônio Histórico e Artístico Nacional) 2000).