Experimental analysis on changes of the porosity of ultrahigh performance concrete at elevated temperatures

Title: Experimental analysis on changes of the porosity of ultrahigh performance concrete at elevated temperatures
Author(s): E. Klingsch, A. Frangi
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: 345 - 352
Total Pages: 8
Nb references: 7
Language: English

Abstract: The risk of spalling can be reduced significantly by adding PP-Fibres to the fresh concrete.
This paper presents results on the changes in pore volume and the distribution of the pore sizes measured with mercury intrusion porosimetry. A UHPC with different amounts of PP-fibres (0, 2- and 3 kg/m3) was used for these tests. First, temperatures causing explosive spalling were analysed by linear heating of concrete cylinders (ø = 150 mm, h = 300 mm). At second stage, dried small concrete cubes with a length of 4 mm were heated to temperatures close to and above these critical temperatures to investigate changes in the porosity. It was observed that the melting PP-fibres causes an increase in the pore volume mainly due to creating additional large pores (1.7·104 nm). However, the analysis of concrete cubes heated above the critical temperature causing explosive spalling showed that spalling mainly causes an increase of very small pores (1-100 nm). This development is not affected by adding of
PP-fibres.

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