Evaluación del daño térmico de columnas de hormigón a gran escala expuestas a altas temperaturas utilizando microscopía electrónica de barrido y difracción de rayos X

Publicado

2018-10-01

Thermal damage evaluation of full scale concrete columns exposed to high temperatures using scanning electron microscopy and X-ray diffraction

Evaluación del daño térmico de columnas de hormigón a gran escala expuestas a altas temperaturas utilizando microscopía electrónica de barrido y difracción de rayos X

Palabras clave:

concrete, high temperature, microstructure, scanning electron microscopy (SEM), x-ray diffraction (XRD) (en)
hormigón, altas temperaturas, microestrutura, microscopía electrónica de barrido (SEM), difracción de rayos X (XRD) (es)

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Autores/as

Bruno Fernandes Universidade do Vale do Rio dos Sinos https://orcid.org/0000-0002-3979-6486
Augusto Masiero Gil Universidade Estadual de Campinas https://orcid.org/0000-0001-6167-7638
Fabrício Longhi Bolina Universidade do Vale do Rio dos Sinos https://orcid.org/0000-0002-0495-099X
Bernardo Fonseca Tutikian Universidade do Vale do Rio dos Sinos https://orcid.org/0000-0003-1319-0547

Resumen (en)
Resumen (es)

When exposed to elevated temperatures, concrete suffers physicochemical changes, resulting in reduction of mechanical properties, cracking and spalling. These macroscopic changes are related to changes in the microstructure of concrete. In this paper, the microstructure of thermally damaged concrete from real-scale reinforced concrete columns was studied, using scanning electron microscopy (SEM) and x-ray diffraction (XRD). Two real-scale reinforced concrete columns, with different concrete mixtures, were exposed to ISO 834 firestandard curve for 4 hours. After heating, concrete core samples were drilled, sectioned and analyzed in different column section depths.Core samples from reference column not exposed to high temperatures, were also obtained. Macroscopic observations showed a change inthe color of concrete exposed to high temperatures. SEM micrographs presented distinct changes in morphology, like coarsening, and thepresence of cracks and voids. XRD diagrams showed a reduction of portlandite and presence of larnite as depth increases.

Cuando se expone a temperaturas elevadas, el concreto sufre cambios fisicoquímicos relacionados con cambios en la microestructura del hormigón. En este artículo, se estudió la microestructura del concreto dañado térmicamente en columnas de hormigón armado a escala real, utilizando microscopía electrónica de barrido (SEM) y difracción de rayos X (XRD). Dos columnas de hormigón armado a escala real, con diferentes mezclas de hormigón, se expusieron a la curva estándar de fuego ISO 834 durante 4 horas. Las observaciones macroscópicas mostraron un cambio en el color del concreto expuesto a altas temperaturas. Las micrografías SEM presentaron cambios distintos en la morfología, como el engrosamiento y la presencia de grietas y huecos. Los diagramas de XRD mostraron una reducción de portlandita y la presencia de larnita a medida que aumentó la profundidad.

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Citas

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