Concrete spalling due to fire exposure and the influence of polypropylene fibres on microcracking

Title: Concrete spalling due to fire exposure and the influence of polypropylene fibres on microcracking
Author(s): S. Huismann, M. Korzen, F. Weise and B. Meng
Paper category : conference
Book title: 2nd International RILEM Workshop on Concrete Spalling due to Fire Exposure
Editor(s): E.A.B. Koenders and F. Dehn
ISBN: 978-2-35158-118-6
e-ISBN: 978-2-35158-119-3
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 327 - 336
Total Pages: 10
Nb references: 14
Language: English

Abstract: This paper presents the results of fire tests with high strength concrete (HSC) elements with and without adding polypropylene (PP) fibres. PP fibres were generally used in concrete to prevent explosive spalling because they increase the permeability of the concrete during heating in the relevant temperature range. As a result the moisture can escape fast enough out of the specimen and pore pressures are reduced. Without PP fibres the dense microstructure of the HSC retards the moisture transport and pore pressures increase until explosive spalling occurs. The reason for PP fibre induced increase in permeability is up to now not sufficiently understood. Based on their research the authors come to the conclusion that microcracking starting from the fibres is the key mechanism of this phenomenon. Therefore the research study is focused on the investigation of the influence of PP fibres on microcracking. For this purpose an acoustic emission (AE) analysis was performed on 600 x 600 x 300 mm3 specimens during a hydrocarbon (HC) fire exposure. Through this innovative technique the monitoring of the crack and spalling development can be realized indirectly with high resolution. This experimental method is a new approach in the context of fire spalling. The AE results were validated by microscopic investigations after the fire tests. Supplementary to the AE analysis pore pressure measurements were performed in different depths of the specimens. These results will be related to the AE results for a better understanding of the interaction between microcracking and pore pressure.

Online publication: 2012-01-17
Publication type : full_text
Public price (Euros): 0.00