TY - JOUR A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meng, Birgit T1 - Polypropylen-Fasern in Hochleistungsbetonen - Wirkungsmechanismen im Brandfall N2 - Bauteile bzw. Tragwerke aus Hochleistungsbetonen müssen in der Regel gegen brandinduzierte Abplatzungen mit geeigneten Maßnahmen geschützt werden, um einen ausreichenden Feuerwiderstand im Brandfall zu gewährleisten. Die bisher wirtschaftlich und technologisch sinnvollste Methode zur Verhinderung von explosionsartigen Betonabplatzungen im Brandfall ist die Zugabe von Polypropylen-Fasern. Die Wirksamkeit der Fasern konnte zwar empirisch gezeigt werden, es stellt sich allerdings die Frage, welche Mechanismen zur Verhinderung der Abplatzungen führen. Der vorliegende Beitrag fasst bisherige Theorien zur Wirkungsweise von Polypropylen-Fasern in brandbeanspruchten Hochleistungsbetonen zusammen und stellt eine innovative Methodologie zur Erforschung der mikrostrukturellen Prozesse vor. Die Ergebnisse zeigen, dass die nach dem Schmelzen und Zersetzen der Polypropylen-Fasern frei werdenden Mikrokanäle durch eine gleichzeitig einsetzende Mikrorissbildung netzartig verbunden werden. Die Mikrorissbildung ermöglicht somit den Abbau von Eigen- und Zwangsspannungen im Beton (mechanischer Effekt) und die Entstehung eines Transportwegesystems für den ausströmenden Wasserdampf (Permeationseffekt).--------------------------------------------------------------------------- Structural members and bearing structures of high performance concrete generally have to be protected against explosive spalling due to fire exposure to guarantee a sufficient fire resistance. Up to now, the economically and technologically most worthwhile method to prevent explosive spalling is the addition of polypropylene fibres. Though the effectiveness of the fibres could be shown empirically, the mechanisms preventing explosive spalling are still debatable. The present article summarizes the existing theories concerning the mode of action of polypropylene fibres in fire exposed high performance concretes and presents an innovative methodology for analysing the micro structural processes. The results show that due to the thermal decomposition of the polypropylene fibres micro channels are created and simultaneously connected due to a netlike micro crack formation. This enables the relief of internal stresses (mechanical effect) and the formation of a permeable transport system for the escaping water vapour (permeation effect). KW - Polypropylen-Fasern KW - Brandschutz KW - Structural fire protection KW - Computertomographie KW - Computed tomography KW - Hochleistungsbeton KW - High performance concrete KW - Messtechnik KW - Mikrorisse KW - Micro cracks KW - Polypropylen-Fasern KW - Polypropylene fibres KW - PP-Fasern KW - Prüfmethoden KW - Rasterelektronenmikroskopie KW - Scanning electron microscopy KW - Risse KW - Schallemissionsanalyse KW - Acoustic emission KW - UHPC KW - Baustoffe KW - Brandschutz KW - Versuche PY - 2012 DO - https://doi.org/10.1002/best.201200024 SN - 0005-9900 SN - 1437-1006 VL - 107 IS - 7 SP - 476 EP - 483 PB - Ernst CY - Berlin AN - OPUS4-26174 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Meng, Birgit T1 - Zur Wirkungsweise von PP-Fasern in brandbeanspruchten Hochleistungsbetonen T2 - 52. DAfStb-Forschungskolloquium 2011, BAM CY - Berlin, Germany DA - 2011-11-07 PY - 2011 AN - OPUS4-25228 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Meng, Birgit ED - Rogge, A. ED - Meng, B. T1 - Zur Wirkungsweise von Polypropylen-Fasern in brandbeanspruchten Hochleistungsbetonen T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 KW - Polypropylen-Fasern KW - Hochfester Beton KW - Schallemissionsanalyse KW - Röntgen 3D-Computertomographie KW - Rasterelektronenmikroskopie PY - 2011 SN - 978-3-9814281-0-0 SP - 134 EP - 140 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25188 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meng, Birgit T1 - The mode of action of polypropylene fibres in high performance concrete at high temperatures T2 - 2nd international RILEM workshop on concrete spalling due to fire exposure CY - Delft, Netherlands DA - 2011-10-05 PY - 2011 AN - OPUS4-24714 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Korzen, Manfred A1 - Weise, Frank T1 - Monitoring of fire damage processes in concrete by pore pressure and acoustic emission measurements T2 - 2nd international RILEM workshop on concrete spalling due to fire exposure CY - Delft, Netherlands DA - 2011-10-05 PY - 2011 AN - OPUS4-24715 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meng, Birgit A1 - Schneider, U. ED - Koenders, E.A.B. ED - Dehn, F. T1 - The mode of action of polypropylene fibres in high performance concrete at high temperatures N2 - It has been shown in fire tests that polypropylene fibres reduce or avoid explosive spalling of high performance concrete. In the critical temperature ränge up to 300 °C the permeability of HPC increases by using polypropylene fibre. Due to this the water vapour, which is the main reason for explosive spalling, can escape. There exist different theories in the literature conceming the micro structural mechanisms, which cause an increase in the permeability. Within the framework of an internal research project at BAM an innovative methodology was developed for experimental verifying of existing theories and to get new insights into this problem The methodology used is unique and has been undertaken here for the first time. This consists of the combination of acoustic emission and ultrasonic measurement during temperature loading and the non-destructive micro structural analysis of cooled down samples with the aid of micro X-ray computed tomography. For the validation of the nondestructive test methods scanning electron microscopic images of prepared samples were undertaken. The results show that due to the thermal decomposition of the polypropylene fibres micro canals emerge. These are connected due to a simultaneous micro cack formation. T2 - 2nd International RILEM workshop on concrete spalling due to fire exposure CY - Delft, The Netherlands DA - 05.10.2011 KW - Spalling KW - Polypropylene fibres KW - High performance concrete KW - Acoustic emission KW - X-ray computed tomography KW - Scanning electron microscopy PY - 2011 SN - 978-2-35158-118-6 SP - 289 EP - 296 PB - RILEM Publications AN - OPUS4-24835 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pereira, F. A1 - Pistol, Klaus A1 - Korzen, Manfred A1 - Weise, Frank A1 - Pimienta, P. A1 - Carré, H. A1 - Huismann, Sven ED - Koenders, E.A.B. ED - Dehn, F. T1 - Monitoring of fire damage processes in concrete by pore pressure and acoustic emission measurements N2 - 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. T2 - 2nd International RILEM workshop on concrete spalling due to fire exposure CY - Delft, The Netherlands DA - 05.10.2011 KW - Ordinary concrete KW - High temperature KW - Gas pore pressure KW - Acoustic emission KW - Spalling PY - 2011 SN - 978-2-35158-118-6 SP - 69 EP - 77 PB - RILEM Publications AN - OPUS4-24818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pistol, Klaus A1 - Weise, Frank T1 - Novel investigation of the behaviour of polypropylene fibres in high strength concrete at high temperatures T2 - 8th fib International PhD symposium in civil engineering CY - Lyngby, Denmark DA - 2010-06-20 KW - Polypropylene fibres KW - Explosive spalling KW - High strength concrete KW - Computer tomography KW - Scanning electron microscopy PY - 2010 SN - 9788778773012 SP - 407 EP - 412 AN - OPUS4-21630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Prinz, Carsten A1 - Weise, Frank A1 - Klobes, Peter T1 - Analysis of thermal induced microstructural changes in self-compacting concrete using mercury porosimetry T2 - XV. Workshop über die Charakterisierung von feinteiligen und porösen Festkörpern CY - Bad Soden, Germany DA - 2010-11-16 PY - 2010 AN - OPUS4-22708 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Apitz, S. A1 - Pistol, Klaus A1 - Weise, Frank A1 - Berger, J. T1 - Untersuchung des Zwängungsverhaltens von selbstverdichtendem Beton bei instationärer Hochtemperaturbeanspruchung bis 750 °C KW - Zwangsspannung KW - Selbstverdichtender Beton (SVB) KW - Hochtemperaturverhalten KW - Polypropylenfasern (PPF) PY - 2012 SN - 978-3-8440-1196-8 VL - 3 SP - 83 EP - 93 PB - Shaker AN - OPUS4-26564 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -