Filtern
Dokumenttyp
- Beitrag zu einem Tagungsband (6)
- Vortrag (6)
- Beitrag zu einem Sammelband (3)
- Posterpräsentation (3)
- Zeitschriftenartikel (1)
- Buchkapitel (1)
- Dissertation (1)
Referierte Publikation
- nein (21) (entfernen)
Schlagworte
- High performance concrete (6)
- High temperatures (6)
- Fire (4)
- Acoustic emission (3)
- Columns (2)
- High temperature (2)
- Polypropylene fibres (2)
- Thermal strain (2)
- Ultrasound (2)
- Brand (1)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (6)
This paper presents the results of an experimental study on the influence of polypropylene (PP) fibres on the thermal strain of high strength concrete (HSC) at temperatures up to 750°C. Concerning this topic only few results can be found in the literature and systematic investigations are missing. However, basic knowledge is necessary to understand the internal damage processes as well as for structural design.
To explain the differences in the thermal strain of HSC with and without addition of PP fibres the internal damage processes were investigated with acoustic emission (AE) analysis and ultrasound (US). Furthermore the weight loss was measured continuously during heating to monitor the drying of the specimen. This novel approach by combining these different methods with strain measurements at high temperatures allows the integral description of the internal damage processes. The results reveal significant differences in the thermal strain of HSC when PP fibres are added. Between 200°C and 250°C the thermal strain of HSC with PP fibres is superimposed by shrinkage caused by accelerated drying. Above 250°C it is lower than that of plain HSC without PP fibres. It is supposed that it is caused by a more homogeneous distribution of micro cracks whereby the fibre beds acting as defects in the concrete.
Hence this paper gives a contribution to the general understanding of the impact of PP fibres in HSC at high temperatures and points out the influence of the fibres on the thermal strain of HSC.
Monitoring of fire damage processes in concrete by pore pressure and acoustic emission measurements
(2011)
This paper presents the combined use of acoustic emission (AE), gas pore pressure and temperature measurements (PT). The simultaneous application of both techniques represents a new methodology in the context of fire spalling and contributes to a better understanding of the mechanisms of fire spalling, particular with regard to the interaction of micro cracking and pore pressure evolution. The study presents fire tests on normal strength concrete specimens with and without reinforcement at ISO Standard fire and at hydrocarbon (HC) fire. Supported by AE-analysis, it can be shown that due to the higher heating rate of the HC-fire in comparison to the ISO Standard fire the damage processes inside the concrete during the exposure are increased combined with augmenting the concrete permeability. As a consequence lower pore pressures were measured. However, despite the lower pore pressures, explosive spalling was observed.