NDTnet 1998 Aug, Vol.3 No.8

Abstract

Neutron radiography (NR) is a very useful non-destructive method for determination of moisture and of other hydrogenous materials (e.g. hydrophobic agents) in laboratory samples of porous building materials. Monitoring of relatively fast (lmm/min) processes of moisture transport in porous building materials is enabled by near real time NR methods based on novel imaging plates neutron detectors (IP-ND, developed by Fuji). Hydrogen content is determined by neutron beam transmission analysis (1). The spatial resolution of this NR technique is about 0.2 mm and detection sensitivity is 0.3 w.% H₂O. Quantitative method was calibrated by a series of standard porous samples with well known moisture content as well as with a standard Plexiglas step wedge.

Fig.: Moisture concentration profiles in a brick sample.

Deterioration of building materials is originated by different processes that all require presence of water and are promo-ted by transport of water and solutions of harmful substances, e.g. SO₂, salts and chlorides etc. Therefore precise quantitative mea-surements of moisture content and 8 monitoring of moisture transport are E important. The time frozen images of an advancing water front in porous samples can be recorded with time resolution of 1-40 sec. In the Figure moisture concentration profiles in a brick sample at different wetting times are presented.

Fast NR imaging techniques and quantitative neutron transmission analysis have a practical application value in the building material and ceramic industries. The verification of the efficiency of various hydrophobic treatments and coatings applied to porous building materials, study of application processes of hydrophobic agents and of various moisture transport phenomena in research on various effective hydrophobic materials are typical routine problems of interest for the building materials industry and in civil engineering.

Reference:
1. T. Nemec, J. Rant, M. Kaling, Proc. 4th International Conf. of Slovenian Society for Non-destructive Testing, Ljubljana, 1997, 151-158.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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