| ABSTRACT: | MICROWAVE INSPECTION OF CIVIL STRUCTURES
F Volgyi
Budapest University Of Technology And Economics, Budapest, Hungary
This paper is devoted for microwave moisture-measurement (aquametry) and composition estimation of
civil structures, because in recent years considerable efforts have been made in applying microwave
technique to test dielectric materials and metals. The first part of this "invited" talk is an overview of the
work done by researchers (all over the World) involved in using microwave (or high frequency
electromagnetic-) signals for non-destructive testing and evaluation (NDT&E) mainly of concrete (in place
and fresh).
In the second part of this paper will be introduced three new instruments developed at Budapest University
of Technology and Economics (BUTE). The first item is a/ direct- contact sensor (DCS), for use in bins of
raw materials (such as sand-, crushed stone) and in concrete mixers. B/ a particle- board monitoring
instrument (PBM), using free- space technique. And c/ a non- contact moisture sensor (NCS), for use in
concrete mixers above the moving mix.
Some innovative solutions are introduced to these instruments. The DCS uses three-frequency integrated
microstrip antennas (MSA) and a protecting hard ceramic cap transformer for sensing reflections at the near-
field. To reach a high accuracy and density- independent operation, a back propagation artificial neural
network (ANN) was developed. Code- modulated-, passive back- scatters are applied at PBM, using
circularly- polarised MSA-s. This complex permittivity monitoring system gives us information about
moisture distribution, abnormal density or glue- overdose or presence of air inclusions in the board (having
dimensions of 3m by 17m), at the moment of its occurrence.
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