Microstructural characteristics of HPC under different thermo-mechanical and thermo-hydraulic conditions

The microstructural characteristics of high performance concrete (HPC) samples were analysed using scanning electronic microscopy (SEM) and X-ray diffraction (XRD) following thermo-hydraulic and thermo-mechanical testing. The relationship between engineering behaviour (transport and mechanical prope...

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Bibliographic Details
Published in:Materials and structures 1999-12, Vol.32 (10), p.727-733
Main Authors: Li, X J, Li, Z J, Onofrei, M, Ballivy, G, Khayat, K H
Format: Article
Language:English
Subjects:
Alloys
Building construction
Building materials
Calcium silicate hydrate
Cement paste
Civil engineering
Concretes
Crack initiation
Electronics
Failure analysis
Failure mechanisms
Fracture mechanics
Materials science
Mechanical properties
Mechanical tests
Microcracks
Microstructure
Porosity
Slaked lime
Thermomechanical properties
Transport
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Summary:The microstructural characteristics of high performance concrete (HPC) samples were analysed using scanning electronic microscopy (SEM) and X-ray diffraction (XRD) following thermo-hydraulic and thermo-mechanical testing. The relationship between engineering behaviour (transport and mechanical properties) and microstructure for HPC was then analysed. The failure mechanism of HPC under thermo-mechanical conditions was also discussed. Lower porosity, a higher content of calcium silicate hydrate (C−S−H) and a lower content of the crystalline-phase calcium hydroxide (CH) in both the cement paste and transition zone all exerted a positive influence on the transport and mechanical properties of HPC. By increasing temperature to 200°C, the evaporation of water led to an increase in capillary porosity as well as to a reduction in the cohesive forces between C−S−H layers, which cause degradation of the concrete’s transport and mechanical properties. Microcracking under thermo-mechanical conditions proved to be the main failure mechanism of HPC.
ISSN:1359-5997
1871-6873
DOI:10.1007/BF02905069