Inspeção de fachadas históricas: levantamento de materiais e danos de argamassas
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
As argamassas de fachada protegem a edificação, seu conteúdo e revelam sua identidade, funções realçadas quando se trata de patrimônio histórico. Elas sofrem pelo intemperismo, umidade, vandalismo, intervenções malsucedidas e vícios de fabricação. A tese apresenta e aplica uma metodologia de levantamento de danos, materiais e técnicas construtivas, para a conservação ou restauro de argamassas de fachadas históricas. Revisa a literatura de preservação arquitetônica e demonstra a importância desse levantamento. Faz uma compilação dos mecanismos de degradação de argamassas históricas. Traz informações práticas sobre acesso vertical à fachada, definição de objetivos de levantamento, representação da evolução histórica, elaboração de formulários de campo e orçamento. Apresenta proposta de formação de inspetores, revisa a bibliografia e propõe metodologia de levantamento de danos, materiais e métodos construtivos. No levantamento de danos, emprega a inspeção visual e ensaio não destrutivo, por percussão com martelo de bordas em ABS. Revê e propõe critérios de amostragem e protocolos de análises laboratoriais. Emprega análise macroscópica, difração de raios-X (DR-X), petrografia e química por digestão ácida. Traz sugestões quanto à síntese e apresentação dos resultados à equipe de restauração. A metodologia prima pela simplicidade e economicidade, foi desenvolvida através de três estudos de caso, sendo dois no Paço de São Cristóvão Pátio Maior e na fachada principal - e a fachada exterior do futuro Museu da Casa da Moeda do Brasil, ambos no Rio de Janeiro, juntos somando aproximadamente 4.400m² de argamassa. As informações de materiais e métodos construtivos contribuíram para o levantamento histórico e compreensão da patologia. O levantamento de danos por percussão indicou 69% de argamassa comprometida (problemas de aderência ou reposição inadequada) no Pátio Maior, apesar da inspeção visual indicar somente 5% de ausência de argamassa por queda. A demolição cuidadosa das argamassas degradadas comprovou um desvio de apenas 4% do levantamento de danos por percussão. O protocolo de análise laboratorial agrupou as amostras pela inspeção macroscópica e/ou DR-X, realizando análises mais completas apenas em representantes destes grupos. Empregou a DR-X na identificação mineralógica. A petrografia foi muito versátil, agregando informações sobre composição mineralógica, granulometria, porosimetria, traço aproximado e história geológica. O traço foi avaliado através da análise química, comprovada para argamassas de areia, cal e/ou cimento, entretanto limitada na presença de agregado carbonático e/ou argila. Os estudos de caso apresentaram composições de envolvendo cal, areia, saibro, cimento e agregado carbonático. Fragmentos de conchas/corais foram encontrados em diversas amostras. As patologias foram relacionadas a torrões de argila na composição da argamassa, falta de aglomerante e incompatibilidade entre emboço e reboco. A apresentação de resultados na forma de mapas temáticos foi eficaz no ambiente multidisciplinar. A aplicação da metodologia se demonstrou viável e útil no apoio às decisões de restauro de argamassas de fachadas históricas, podendo ser aplicada também a argamassas contemporâneas.
Façade renders protect the building, its content and reveal its identity. Those roles are even more important on cultural heritage buildings. Renders decay under weathering, damp, vandalism, unsuccessful interventions and manufacturing defects. This thesis presents and applies an assessment methodology concerning historical façades plasters, construction methods and damage. The architectural preservation literature is reviewed, highlighting the importance of such assessment. Rendering decay mechanisms are compiled, focused on historical mortars. Practical field information is described, including façade vertical access, assessment objectives definition, historical evolution representation, field forms design and implied costs. An inspector formation proposal is outlined. Materials, construction methods and damage assessment literature are reviewed and a method is proposed. Damage assessment relies on visual inspection and nondestructive essay, using ABS faced hammer percussion. Sampling criteria and laboratory protocols are reviewed and proposed. The proposed protocol applies macroscopic analysis, X-ray diffraction (XRD), petrography and acid digestion chemical analysis. Suggestions are made concerning results synthesis and presentation to preservation team. Presented methodology, based on simplicity and low cost, was developed during three case studies: two on São Cristóvão Palace Main Court and Main Façade- and the exterior façades of the future Casa da Moeda do Brasil Museum, both in Rio de Janeiro. The three studies account for roughly 4.400 m² of assessed rendered surface. Construction methods and materials assessment contributed to the buildings historical studies and pathology comprehension. Percussion assessment evaluated damage on 69% of the Main Court rendered area, although visual inspection accounted only 5% of missing render. Careful demolition of damaged render proved a 4% deviation from percussion assessment forecast. Laboratory protocol grouped samples based on macroscopic evaluation and/or XRD. Only group representatives were submitted to further analysis. XDR was used for mineralogical identification. Petrography proved a very versatile essay, yielding data on composition, granulometry, porosimetry, approximated formulation and geological history. Plaster composition was evaluated by chemical analysis blind proofed for sand, lime and/or Portland cement, though impaired when carbonate aggregate and clay particles are present. Case studies showed various mortar formulations, comprising lime, sand, clay, cement and carbonate aggregate. Sea shell/reef fragments were found in several samples. Pathology was related to the presence of clay lumps, lack of binder and incompatibility between plaster layers. Thematic maps were successfully used in results presentation to multidisciplinary teams. The proposed methodology is viable and useful, supporting decisions within architectural preservation of historical façades plaster rendering. Contemporary façades can benefit from the methodology as well.
Façade renders protect the building, its content and reveal its identity. Those roles are even more important on cultural heritage buildings. Renders decay under weathering, damp, vandalism, unsuccessful interventions and manufacturing defects. This thesis presents and applies an assessment methodology concerning historical façades plasters, construction methods and damage. The architectural preservation literature is reviewed, highlighting the importance of such assessment. Rendering decay mechanisms are compiled, focused on historical mortars. Practical field information is described, including façade vertical access, assessment objectives definition, historical evolution representation, field forms design and implied costs. An inspector formation proposal is outlined. Materials, construction methods and damage assessment literature are reviewed and a method is proposed. Damage assessment relies on visual inspection and nondestructive essay, using ABS faced hammer percussion. Sampling criteria and laboratory protocols are reviewed and proposed. The proposed protocol applies macroscopic analysis, X-ray diffraction (XRD), petrography and acid digestion chemical analysis. Suggestions are made concerning results synthesis and presentation to preservation team. Presented methodology, based on simplicity and low cost, was developed during three case studies: two on São Cristóvão Palace Main Court and Main Façade- and the exterior façades of the future Casa da Moeda do Brasil Museum, both in Rio de Janeiro. The three studies account for roughly 4.400 m² of assessed rendered surface. Construction methods and materials assessment contributed to the buildings historical studies and pathology comprehension. Percussion assessment evaluated damage on 69% of the Main Court rendered area, although visual inspection accounted only 5% of missing render. Careful demolition of damaged render proved a 4% deviation from percussion assessment forecast. Laboratory protocol grouped samples based on macroscopic evaluation and/or XRD. Only group representatives were submitted to further analysis. XDR was used for mineralogical identification. Petrography proved a very versatile essay, yielding data on composition, granulometry, porosimetry, approximated formulation and geological history. Plaster composition was evaluated by chemical analysis blind proofed for sand, lime and/or Portland cement, though impaired when carbonate aggregate and clay particles are present. Case studies showed various mortar formulations, comprising lime, sand, clay, cement and carbonate aggregate. Sea shell/reef fragments were found in several samples. Pathology was related to the presence of clay lumps, lack of binder and incompatibility between plaster layers. Thematic maps were successfully used in results presentation to multidisciplinary teams. The proposed methodology is viable and useful, supporting decisions within architectural preservation of historical façades plaster rendering. Contemporary façades can benefit from the methodology as well.
Palavras-chave
Argamassas, Inspeção de fachadas, Patrimônio histórico, Cultural heritage, Façade assessment, Plaster render