TY - JOUR A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meng, Birgit A1 - Diederichs, U. T1 - Polypropylene fibres and micro cracking in fire exposed concrete N2 - Though, concrete in general is a non-combustible building material, modern High Performance Concrete (HPC) is very susceptible to violent explosive spalling during a fire attack. This requires protective measures for fire safety design of concrete structures. The current most worthwhile method to prevent explosive spalling is the addition of monofilament Polypropylene fibres (PP-fibres). However, since it has become common knowledge that PP-fibres are suitable for fire safety design, a variety of theories concerning the mode of action of PP-fibres have been suggested. The present article summarizes the most important hypothesis and presents an innovative method for the analysis of micro structural processes in heated specimens. The results show that due to the thermal decomposition of PP-fibres capillary channels are created. Simultaneously, a netlike micro crack formation occurs, which connects these capillary channels. 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 - Concrete KW - Fire Spalling KW - Micro-Crack KW - Polypropylene Fibres PY - 2014 U6 - https://doi.org/10.4028/www.scientific.net/AMR.897.284 SN - 1022-6680 SN - 1662-8985 VL - 897 SP - 284 EP - 289 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-30383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Pistol, Klaus A1 - Huismann, S. A1 - Diederichs, U. A1 - Pimienta, P. A1 - Jumppanen, U.M. A1 - Mindeguia, J.C. T1 - Stress-strain-relation, compressive strength and modulus of elasticity N2 - This chapter report the most recent experimental results on mechanical behaviour at high temperature of high-performance concretes. After a short introduction, subsection 5.2 describes the main testing methods that were used in the analysed studies. Sub-section 5.3 collects and compares; the temperature-dependency of the compressive strength and modulus of elastici1ty of many experimental studies. The influence of parameters such as the initial compressive strength, the type of aggregate, the presence of additions, the W/C ratio, the moishrre content and the way the mechanical test was performed is analysed. Sub-section 5.4 presents the experimental results obtained under a constant temperature, i.e. creep tests at high temperature. Sub-section 5.5 presents experimental results obtained under increasing temperahrre. These results allow assessing the free thennal strain of concrete (when no mechanical load is applied) and the so-called "transient the1mal strain". Finally, subsection 5.6 collects and analyses the few results conceming the temperature-dependency of the tensile strength of high-perfo1mance concretes. KW - Stress-strain-relation KW - High temperature PY - 2019 SN - 978-3-319-95431-8 SN - 978-3-319-95432-5 SN - 2213-204X SN - 2213-2031 SP - 89 EP - 105 PB - Springer CY - Swizerland AN - OPUS4-47212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -