Spalling of concrete as studied by NMR

Title: Spalling of concrete as studied by NMR
Author(s): L. Pel, G.H.A. van der Heijden, H. Huinink
Paper category : conference
Book title: 2nd International RILEM Symposium on Advances in Concrete through Science and Engineering
Editor(s): J. Marchand, B. Bissonnette, R. Gagné, M. Jolin and F. Paradis
Print-ISBN: 2-35158-003-6
e-ISBN: 2351580028
Publisher: RILEM Publications SARL
Publication year: 2006
Nb references: 7
Language: English

Abstract: During the past twenty years concrete has developed in both strength and durability. A downside to these improvements is the increased risk of explosive spalling in case of fire. Different factors such as heating rate, applied loading, permeability, and moisture saturation play an important role in spalling. One of the explanations for spalling is the pressure build up by evaporating moisture which is unable to escape. To study the moisture migration inside concrete during intense heating a dedicated Nuclear Magnetic Resonance (NMR) setup was built.
With this setup one dimensional moisture profiles can be measured as function of time. For the magnetic field a 1.5 T medical scanner (Philips, Gyroscan) is used. The samples can be heated to temperatures up to 250 oC. Preliminary measurements on fired-clay brick and calcium-silicate brick have shown that during heating a receding drying front is observed. In the fired-clay brick the position of the drying front correlates with the position at which 100 oC is reached. However, in both the calcium-silicate brick and the concrete samples the drying front lags behind on the temperature. As a result water is superheated to a temperature above 100 oC, which could result in large pressures.

Keywords: NMR concrete spalling moisture temperature

Online publication: 2006-08-02
Classification: 3.3 Theme 3: Monitoring, Repair and Maintenance of Concrete Structures
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580028.107