COMUNICAÇÃO TÉCNICA _____________________________________________________________________________________________________________________________________________________ _________________________________________________ Nº 171296 Why use the lab to characterize old mortar coatings? Claudia Bastos do Nascimento Mirian Cruxên Barros de Oliveira Valdecir Angelo Quarcioni Pôster apresentado no 16th annual International Preservation Trades Workshop ‐ IPTW 2012, Charleston A série “Comunicação Técnica” compreende trabalhos elaborados por técnicos do IPT, apresentados em eventos, publicados em revistas especializadas ou quando seu conteúdo apresentar relevância pública. ___________________________________________________________________________________________________ Instituto de Pesquisas Tecnológicas do Estado de São Paulo S/A - IPT Av. Prof. Almeida Prado, 532 | Cidade Universitária ou Caixa Postal 0141 | CEP 01064-970 São Paulo | SP | Brasil | CEP 05508-901 Tel 11 3767 4374/4000 | Fax 11 3767-4099 www.ipt.br WHY USE THE LAB TO CHARACTERIZE OLD MORTAR COATINGS? Claudia Bastos do Nascimento1; Mírian Cruxên Barros de Oliveira2; Valdecir Angelo Quarcioni2 1 Instituto do Patrimônio Histórico e Artístico Nacional - IPHAN, Brazil 2 Instituto de Pesquisas Tecnológicas do Estado de São Paulo, IPT, Brazil 4. Results – Study Case of Sobradão Aguiar Vallin (Bananal/SP) 1. Abstract The present work aims to draw attention to laboratory and human resources available in research institutes laboratories, especially in the IPT-Institute for Technological Research of the State of São Paulo, Brazil, to subsidize the technical survey of built heritage and its restoration projects, specifically in the case of inorganic mortar coatings. It also aims to highlight the importance of interdisciplinary work required in these cases. The different stages of laboratory assistance and the benefits derived are presented in details, always seeking the care and preservation of the built heritage. Thus, it is essential for investment promotion agencies in project financing laboratory infrastructure, multidisciplinary research projects focused on technical and scientific research applied to cultural heritage.. This study related of the Sobradão Aguiar Vallin building was requested by the former Department of Recovery of Cultural Property in the State of São Paulo, responsible for the collection of samples sent to our laboratory. Therefore, only the characterization of the two samples of mortar coating were performed, identified as external coating and internal coating. In both samples the renderings consisted of mixed cement mortars, lime and quartz sand with high fines content (39% in the inner and 30% in the outer coating). The proportions binder: aggregate, in mass, is 1: 10.4 for the internal coating and for 1: 18.7 for the outer coating. 2. Introduction It is essential to promote technical and political discussion about the necessities of exchange among restorers of built heritage and support laboratories in order to facilitate financial resource desirable for the development of research technical-scientific nature of the buildings, their building systems and their materials. This poster will try to answer initially two questions, central to this discussion: • Why use the laboratory characterization? • When you use a lab? Figures 2 to 5 show the grading curve of the aggregate and the microscopic characteristics of the mortars coating studied. Assumptions: • The principle of minimum intervention • Research of the heritage property with technical-scientific approach • Follow up with technical and scientific support for the intervention and the use of appropriate records of all activities. According to the obtained informations, the walls of the building are made of rammed earth and adobe. We considered the proportions binder: aggregate compatible with the recommendation of CRATerre (1983) coverings sealing elements in soil. 3. Working Methods The Figure 1, based on Lichtenstein (1986), presents a flowchart with the different stages of a study of historical building which precede the restoration project. Cadastral Survey Technical Survey - Research of mortar coatings: Inspection Critical analysis of technical documentation The experience of IPT - Institute for Technological Research of the State of São Paulo is based on two aspects: - Inspection-building techniques. - Characterization of materials to formulate repairing materials. visual assessment monitoring essays in loco Survey geometric / spatial Characterization of architectural style and construction techniques Historical Survey Bibliographical Survey Sampling Characterization and laboratory evaluation INVESTIGATION Identification of anomalies and deterioration mechanisms The goals of these aspects are: a) Evaluation of the state of conservation and investigation of the causes of pathological manifestations for specifying corrective, preventive measures and direct sampling, which is derived fundamentally from tactile and visual inspection of the building, complemented when necessary with tests to verify in situ the bond strength, and laboratory analysis, such as verification of soluble salts and microorganisms (fungi / algae). The pathologic manifestations commonly found in the coatings of buildings of historical value studied by our lab are: presence of moisture (ascending, accidental) presence of biofilm (fungi, algae) and higher plants, soluble salts, shrinkage cracking by thermal variation or by presence of higher plants. The presence of cement is an evidence that it was incorporated coating after construction, since the building is from 1860, and the start of production of cement in Brazil dates from 1888, and culminated in 1924 with the implementation of a industrial plant in Perus in São Paulo State by the Companhia de Cimento Portland. We don’t have any registers about imported cement used in this building. Identification of agents and deterioration mechanisms Recommendations for intervention 5. Conclusions Simulation Laboratory Performance evaluation Physical compatibility lower mech. resist. Chemical Compatibility Restoration Project Figure1 - Flowchart of the stages of the restoration project. b) Identification of materials and construction techniques in order to understand the history of the building and supporting the attribution of value. Multidisciplinary scientific studies should be provided in phase of fundraising and planning activities in order to provide the financial resources and the time needed to research activity. The labs experience, added to the restorer, minimizes the risks of inappropriate interventions and promotes the search for solutions that respect the principle of minimum intervention. Thus, it is essential for investment promotion agencies in project financing laboratory infrastructure, multidisciplinary research projects focused on technical and scientific research applied to cultural heritage. activities. 6. References In this case, the characterization of isolated samples, no further details of the building obtained in situ, as modifications or repairs performed in over a hundred years, makes it difficult to do precise suggestions. So, our recommendations were based in the literature for buildings constructed of earth (CRATerre, 1983). 7. Acknowledgements IPT - Institute for Technological Research ooacIPTtivities. ooacIPTtivities. The Getty Foundation IPTPTçççIPTIPTIPTPTçççIPTIPT APT - Association for Preservation Technology International • The selection of instrumental techniques depend on the goals, as mentioned, however, there is a tendency among the technical community to perform physical, chemical, mineralogical and microstructural. Generally we use: mineralogical analysis by X-ray diffraction, petrographic analysis (optical microscopy), particle size analysis of the aggregate by sieving and sedimentation and mix proportion determination (by chemical analysis). A natural consequence of the characterization of mortars is the formulation of repair mortars, but it is not an activity performed routinely. The formulation of mortar should be the object of careful study, especially when the mortar presents specific aesthetic characteristics, which require greater care. The formulation of mortar repair occurs from the characterization of mortar building and characterization of materials available in the market. The selection of the formulation is linked to the evaluation of the appearance and texture similar to the original coating and evaluation of physical performance (water absorption, no shrinkage cracking) and mechanical (bond strength). CRATerre. CENTRE DE RECHERCHE ET D’APPLICATION TERRE. 1983. Construire em Terre. 2 ed. Paris: Ed. Alternatives. 286 p. INSTITUTO DE PESQUISAS TECNOLÓGICAS DO ESTADO DE SÃO PAULO (IPT). Caracterização de duas amostras de argamassa de revestimento do Sobradão Aguiar Vallin. Relatório Técnico no 54816 . São Paulo. SP. 2001. LICHTENSTEIN, N. B. Patologia das construções. São Paulo: EPUSP. (Boletim técnico 06). 1986. activities.