Elton Bauer

Infrared thermography – evaluation of the results reproducibility

Purpose – Infrared thermography is increasingly being used to diagnose pathologies in buildings, such as facade defects. The purpose of this paper is to assess the results reproducibility and the equipment influence on the measurements. To do so, it was defined as case study the assessment of rendering delamination. Design/methodology/approach – Two infrared cameras of different makers were used to detect the presence of defects deliberately created in specimens. The tests were done in the laboratory with a heat source. The defects were detected through a temperature gradient between the zones with and without defect. Findings – With this thermographic imaging, it was possible to identify the defects in the specimen both qualitatively and quantitatively. The results were found to be reproducible in the three cycles performed. The influence of the equipment on the results was of little significance for the quantitative assessment criterion “temperature difference between zones with and without defect”, but...

Criteria for Identification of Ceramic Detachments in Building Facades with Infrared Thermography

Infrared thermography is a nondestructive technique with great application potential to study the pathologies of buildings. The use of passive thermography to evaluate building facades subjected to sun incidence has allowed interesting advances in the identification of regions with initial detachments that are not visible on the facade surfaces. There are, however, several difficulties in the methodology, especially regarding the best moment to visualize the anomalies. These moments depend mainly on the heat flow in the facade, which is not constant. The objective of this study is to identify the best conditions to visualize the anomalies by performing field and laboratory studies to evaluate delta-T and contrast functions. To this end, a laboratory study was developed. It consisted of heating and cooling experimental base plates with manufactured internal defects, which were monitored by a sequence of thermograms obtained continuously. The field study consisted of evaluating an area of a building facade with detachment patches. The thermal evolution of the facade was monitored continuously by thermography for 10 h. The results indicate that delta-T cannot be used as the sole parameter to identify the anomalies. It is also highlighted that knowing the direction of heat flow is important since the contrast functions have shown that the anomalies are best visualized at the beginning of the heat flow, heating or cooling. It proved that the criteria obtained in the laboratory are applicable to field studies, especially if it is possible to analyze previously the heat flow on the facade.

Friction Influence between Particles in the Behavior of Flow of Lime-Rendering Mortars

The behavior and properties of rendering mortars, in the fresh state, are influenced primarily by particle grading, amount of water employed, and the shape and surface texture of particles. Production processes and application of rendering mortars demand an appropriate adjustment in their materials so that the plasticity and consistency need to be optimized allowing an appropriate execution of rendering. The friction between particles of sand is decisive in the rheological behavior of mortars. In this context, the present study evaluates the mortar flow behavior focusing on the influence of microfine content and grading of sands on friction angle of mortars. For experimental development, mortars that differ according to binder/aggregate ratios and aggregate grading distributions were used, in addition to using sands with different microfine contents. The mortar consistencies were established based on the cone penetration test. The mortars were tested to determine the internal friction angle using the direct shear test. The yield stress was obtained from the Vane test. The results indicate a relationship between the microfine content and the internal friction angle of the mortars, identifying a strong influences of friction under the behavior of flow of the rendering mortars.

Matriz de análise do índice de chuva dirigida (ICD) para a cidade de Brasília-DF

As condicoes de exposicao da envoltoria do edificio afetam a sua durabilidade. A acao combinada dos agentes de degradacao que atuam nas fachadas acelera a degradacao, comprometendo o desempenho higrotermico e diminuindo a vida util da edificacao. Um dos principais agentes de degradacao e a acao da chuva dirigida, resultante do efeito combinado de chuva e vento, que intensifica o umedecimento da fachada e as infiltracoes. Este trabalho apresenta a determinacao dos indices de chuva dirigida (ICD) anuais e mensais para a cidade de Brasilia-DF, com base em tres periodos: 1961-1990, 1991-2000 e 2001-2010. Ainda, estabelece uma matriz de referencia para analise do grau de exposicao das fachadas a degradacao pela acao da chuva dirigida direcional, visando a selecao de estrategias arquitetonicas que influenciam a vida util da envoltoria da edificacao. Para a determinacao do indice de chuva dirigida direcional (ICDd) foi adotado o metodo semi-empirico de mensuracao proposto por Lacy. Os valores encontrados para os ICD- anual mostram que Brasilia encontra-se na faixa de classificacao Moderado (3 ≤ ICD < 5). Conclui-se que, mesmo sendo Brasilia classificada na faixa de condicao de exposicao Moderada, os ICDd-mensal mostram que o efeito combinado de chuva e vento nos meses chuvosos, principalmente de novembro a marco, pode ser agressivo para a durabilidade e vida util das fachadas. Quando observada a matriz de analise que relaciona os ICDd-mensal com as faixas de direcao do vento, verifica-se que as fachadas mais expostas a acao das chuvas dirigidas sao aquelas orientadas para Leste, Nordeste e Norte, seguidas pela Noroeste.Palavras-Chave: chuva dirigida, indice de chuva dirigida, fachada, durabilidade, desempenho.