An experimental method to investigate concrete spalling in temperature

Title: An experimental method to investigate concrete spalling in temperature
Author(s): G. Debicki, R. Haniche and F. Delhomme
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: 189 - 195
Total Pages: 7
Nb references: 9
Language: English

Abstract: In a concrete exposed to high temperatures, two indissociable processes arise: a “thermomechanical” process in which the gradient of thermal deformation generates stresses within the material and a “thermo-hydrous” process which generates driving force to put in movement vapour and liquid water. The last one induces a drying process at the surface and an increase of moisture inside the material which can also generate, by gas pressure and/or water dilatation, stresses within the material. An explosive spalling especially caused by the last process can appear for some kinds of concrete. To detect the explosive spalling sensibility of a concrete mixture, a simple test on spherical specimens is proposed and justified.
To investigate this method, an experimental program has been led. The studied mixtures are high performance concrete with or without polypropylene fibres. Two different stored methods are used: under water and in an air-tight plastic bag. The size effect is also analysed by testing three sphere diameters: 12, 18, 24 cm. The heating rate is 5 °C.min-1. The data recorded are the mass specimen, the temperatures on the surface and in the centre of the sphere.
This exploratory work brings the following elements: a critical percentage of polypropylene fibre to avoid spalling is proposed, the scattering of the results seems reduced and the smaller specimens diameter accentuate the thermo-hydrous process.

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