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Article Dans Une Revue Materials Année : 2022

Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes

Résumé

Concretes can be exposed to a magnesium attack in several environments leading to the for-mation of magnesium silicate hydrates (M-S-H) and brucite (MH). The formation of M-S-H is likely to alter the properties of the cement matrix because it is linked to the decalcification of C-S-H. However, relatively few data on M-S-H exist in the literature. In order to characterize, physically and mechanically, the M-S-H phase, pure M-S-H cohesive pastes are needed. This work studies the formation of cohesive M-S-H pastes made with MgO-to-SiO2 atomic ratios of 0.78, 1 and 1.3, from two types of silica (silica fume or colloidal silica) and under 20 °C and 50 °C thermal curing. X-ray diffraction and thermogravimetric analyses confirmed that the consump-tion of brucite and the formation of M-S-H were quicker with a 50 °C curing. Energy-dispersive X-ray spectroscopy and microtomography showed that colloidal silica enabled a better distribu-tion of the particles than silica fume. Microstructural characterizations were conducted under the protocol with colloidal silica and 50 °C thermal curing. Porosity investigations allowed to describe the M-S-H pastes as highly porous materials with a low content of micropores in comparison with mesopores. The type of mixing influenced the mesopore size distribution.
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Dates et versions

hal-03565401 , version 1 (10-02-2022)

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Charlotte Dewitte, Alexandra Bertron, Mejdi Neji, Laurie Lacarriere, Alexandre Dauzeres. Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes. Materials, 2022, 15 (2), pp.547. ⟨10.3390/ma15020547⟩. ⟨hal-03565401⟩
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