A synthesis of work carried out for several years within our laboratory is presented. The first p... more A synthesis of work carried out for several years within our laboratory is presented. The first part includes an experimental study. The tests are performed on hollow cylindrical concrete specimens, subjected to compressive loading. At stress levels lower than 80 % of the peak stress, the variation of permeability is small and it is slightly influenced by the stress, but as the load exceeds 80 % of the peak stress, micro-cracking increases rapidly, causing an increase of the permeability and a greater sensitivity to the applied load. In the post-peak phase the increase of permeability is much larger due to significant crack width growth. The effects of the applied load on permeability are greater with temperature. Finally, the experimental results seem to agree with the format of coupled evolution of the permeability due to damage and temperature assumed by Gawin et al. [ 1 0]. The second part of this paper includes a numerical study. The lattice mechanics model is extended to the hydraulic problem and, for this case, it appears that permeability is the size independent variable. Additionally, the evolution of permeability with damage and with stress ratio in the pre-peak phase is compared with experimental results on different types of concrete.
L'objectif de cette étude est de caractériser l'interaction entre endommagement, température et p... more L'objectif de cette étude est de caractériser l'interaction entre endommagement, température et perméabilité du béton de structure. Les essais sont effectués sur des échantillons cylindriques creux, soumis à une compression uniaxiale et à des températures allant jusqu'à 150 °C. Les résultats obtenus montrent que, pour un chargement inférieur à 80-85 % du chargement maximal, la variation de la perméabilité reste faible et peu influencée par le chargement. Quand le chargement excède 80-85 % du chargement maximal et approche le pic, l'endommagement croît rapidement, entraînant une augmentation importante de la perméabilité. Dans la phase post-pic, l'accroissement de la perméabilité devient très significatif suite à l'ouverture des macrofissures. L'augmentation de la perméabilité avec le chargement mécanique appliqué semble s'accroître à température élevée, provoquant l'altération de la structure poreuse du béton. Enfin, les résultats obtenus révèlent que les effets de l'endommagement et de la température peuvent être découplés pour l'estimation de l'évolution de la perméabilité du béton.
The objective of this study is to investigate damage-temperature-stress level-permeability intera... more The objective of this study is to investigate damage-temperature-stress level-permeability interactions in structural concrete. The tests are performed on hollow cylindrical concrete specimens, subjected to compressive loading and temperature up to 150°C. The results emphasize that at stress levels lower than 80% of the peak stress, the variation of permeability is small and it is slightly influenced by the stress. As a matter of fact, the permeability under load is smaller than the permeability measured after unloading. As the load exceeds 80% of the peak stress, microcracking increases rapidly, causing an increase of the permeability and a greater sensitivity to the applied load, i.e. a noticeable difference between the permeability measured under load and after unloading, the first becoming greater than the latter. In the post-peak phase the increase of permeability is much larger due to significant crack width growth. The increase of permeability with the applied load seems to be greater with temperature, inducing further alterations of concrete and dilation of the porous structure of the material. Finally, the experimental results seem to agree with the format of coupled evolution of the permeability due to damage and temperature assumed by Gawin et al. [D. Gawin, C.E. Majorana, B.A. Schrefler, Numerical analysis of hygro-thermal behaviour and damage of concrete at high temperature, Mechanics of Cohesive-Frictional Materials 4 (1999) 37-74.].
A synthesis of work carried out for several years within our laboratory is presented. The first p... more A synthesis of work carried out for several years within our laboratory is presented. The first part includes an experimental study. The tests are performed on hollow cylindrical concrete specimens, subjected to compressive loading. At stress levels lower than 80 % of the peak stress, the variation of permeability is small and it is slightly influenced by the stress, but as the load exceeds 80 % of the peak stress, micro-cracking increases rapidly, causing an increase of the permeability and a greater sensitivity to the applied load. In the post-peak phase the increase of permeability is much larger due to significant crack width growth. The effects of the applied load on permeability are greater with temperature. Finally, the experimental results seem to agree with the format of coupled evolution of the permeability due to damage and temperature assumed by Gawin et al. [ 1 0]. The second part of this paper includes a numerical study. The lattice mechanics model is extended to the hydraulic problem and, for this case, it appears that permeability is the size independent variable. Additionally, the evolution of permeability with damage and with stress ratio in the pre-peak phase is compared with experimental results on different types of concrete.
L'objectif de cette étude est de caractériser l'interaction entre endommagement, température et p... more L'objectif de cette étude est de caractériser l'interaction entre endommagement, température et perméabilité du béton de structure. Les essais sont effectués sur des échantillons cylindriques creux, soumis à une compression uniaxiale et à des températures allant jusqu'à 150 °C. Les résultats obtenus montrent que, pour un chargement inférieur à 80-85 % du chargement maximal, la variation de la perméabilité reste faible et peu influencée par le chargement. Quand le chargement excède 80-85 % du chargement maximal et approche le pic, l'endommagement croît rapidement, entraînant une augmentation importante de la perméabilité. Dans la phase post-pic, l'accroissement de la perméabilité devient très significatif suite à l'ouverture des macrofissures. L'augmentation de la perméabilité avec le chargement mécanique appliqué semble s'accroître à température élevée, provoquant l'altération de la structure poreuse du béton. Enfin, les résultats obtenus révèlent que les effets de l'endommagement et de la température peuvent être découplés pour l'estimation de l'évolution de la perméabilité du béton.
The objective of this study is to investigate damage-temperature-stress level-permeability intera... more The objective of this study is to investigate damage-temperature-stress level-permeability interactions in structural concrete. The tests are performed on hollow cylindrical concrete specimens, subjected to compressive loading and temperature up to 150°C. The results emphasize that at stress levels lower than 80% of the peak stress, the variation of permeability is small and it is slightly influenced by the stress. As a matter of fact, the permeability under load is smaller than the permeability measured after unloading. As the load exceeds 80% of the peak stress, microcracking increases rapidly, causing an increase of the permeability and a greater sensitivity to the applied load, i.e. a noticeable difference between the permeability measured under load and after unloading, the first becoming greater than the latter. In the post-peak phase the increase of permeability is much larger due to significant crack width growth. The increase of permeability with the applied load seems to be greater with temperature, inducing further alterations of concrete and dilation of the porous structure of the material. Finally, the experimental results seem to agree with the format of coupled evolution of the permeability due to damage and temperature assumed by Gawin et al. [D. Gawin, C.E. Majorana, B.A. Schrefler, Numerical analysis of hygro-thermal behaviour and damage of concrete at high temperature, Mechanics of Cohesive-Frictional Materials 4 (1999) 37-74.].
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