SEDL / STP / STP691-EB / STP36064S

Microstructure of Concrete in Aggressive Environments

Regourd, M
Doctor of Physical Science, Engineer CNAM and Engineer, Centre D'Etudes et de Recherches de L'Industrie des Liants Hydrauliques, Paris,

Hornain, H
Doctor of Physical Science, Engineer CNAM and Engineer, Centre D'Etudes et de Recherches de L'Industrie des Liants Hydrauliques, Paris,

Mortureux, B
Doctor of Physical Science, Engineer CNAM and Engineer, Centre D'Etudes et de Recherches de L'Industrie des Liants Hydrauliques, Paris,

Pages: 16    Published: Jan 1980

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Abstract

All the constituents of concrete can be attacked. Some degradations occur after a long period of time. So, it is important to know the chemical and physical mechanisms of the corrosion and the behavior of built structures. In our studies on the durability of concrete, chemical and technological tests have been completed by microstructure examination with scanning electron microscopy and X-ray diffraction. In the present stage of our research into the attack of concrete by seawater, several factors can be noted. The formation of expansive ettringite is related to the content, the crystalline form, and the granularity of tricalcium aluminate. The carbonation reaction transforms ettringite into thaumasite. The dissolving of lime-rich compounds like hydrated silicates C-S-H brings about their progressive transformation into Ca-Mg silicates. Some aggregates have been found to have reacted with alkalis. A dense concrete with a high cement content will offer a good resistance to chemical and physical attacks.