Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2019 (23) (entfernen)
Dokumenttyp
- Beitrag zu einem Tagungsband (9)
- Vortrag (7)
- Zeitschriftenartikel (5)
- Posterpräsentation (2)
Schlagworte
- AKR (5)
- Innenhydrophobierung (4)
- UHPC (4)
- Microstructure (3)
- Moisture clog (3)
- 1H-NMR (2)
- AKR-Betonversuche (2)
- ASR (2)
- Baustoffe (2)
- Betonfahrbahn (2)
Organisationseinheit der BAM
- 7.1 Baustoffe (23) (entfernen)
Eingeladener Vortrag
- nein (7)
Thermally-induced moisture transport in high-performance concrete studied by X-ray-CT and 1H-NMR
(2019)
The thermohydraulic damage mechanism is one of the primary causes for explosive spalling of highperformance concrete. This paper presents the spatially- and temporally-resolved analysis of the thermally-induced moisture transport and reconfiguration processes by means of X-ray-CT and 1HNMR.
Thermal testing results for a high-performance concrete, which is sensitive to explosive spalling and which was prepared with and without added polypropylene fibres, are presented in this paper. These results indicate that the addition of fibres leads to a faster and deeper migration of the drying front and, thus, to a lower likelihood of vapour-pressure induced explosive spalling.
The aim of this paper is to implement a numerical model to reproduce the nonlinear behavior of cob walls under shear loading.
Axial compression, pull-off, and diagonal compression tests were carried out to derive the mechanical parameters. In addition, the stressstrain relationships, the nonlinear behavior, and the failure modes were defined. The experimental results were then used to calibrate a finiteelement model. The material behavior was simulated through a macromodeling approach adopting the total strain rotating crack model.
A sensitivity analysis was conducted to assess the effects of varying the parameters with higher uncertainty on the structural behavior.
The numerical model achieved good correspondence with the experimental results in terms of simulation of the shear stress–shear strain relationship and of damage pattern.
Water migration in one-side heated concrete: 4D in-situ CT monitoring of the moisture-clog-effect
(2019)
Explosive spalling due to fire exposure in concrete structures can lead severe damage and, in the worst case, to premature component failure. For this reason, an in situ investigation of water Migration in concrete due to surface heating was undertaken.
During these experiments, a miniaturized concrete specimen within a confining and insulating double-hull was subjected to surface heating during simultaneous X-ray computed tomography (CT) scanning. Through the use of subtraction-based Image analysis techniques, it was possible to observe and quantify not only drying within areas of the concrete matrix close to the heated surface, but also the migration of moisture to both pore and matrix regions deeper within the specimen. It was also discovered that the correction of CT images for specimen deformation using DVC and variable detector performance using calibrated image filters significantly improved the quality of the results. This clearly demonstrates the potential of X-ray CT for evaluation of other rapid-density-change phenomena in concrete and other building materials.