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 T2 - 2nd International RILEM workshop on concrete spalling due to fire exposure (Proceedings) 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 -