We are currently working on the microwave sensor which can detect the
electrical properties (permittivity and thickness) of different layers of
materials from the analysis of microwave reflection. The permittivity is
dependent upon the amount of moisure, matretial type and air void inside
different layers of pavement. The method, however, will not ne useful if the
pavement is very damp. Water will absorb all energy and hence will not
peneterate deep enough.
The project is still at develping stage we have carried out some lab
experiments with acrylic sheets and it works with 99.9% accuracy.
Kailash Thakur, D. Sc.
Electromagnetic Sensing, Imaging and Sensing
Industrial Research Ltd, 24 Balfour Rd, Parnell
Auckland, New Zealand
ph: +64 9 373 8666
ph: +64 9 626 6282 (a/h)
fax: +64 9 302 8106
email: [log in to unmask]
web: http://www.vision.irl.cri.nz/me_team/kailash.html
Conference web: http://www.isema2003.org
-----Original Message-----
From: The list is for the use of academics and others interested in
technical, op [mailto:[log in to unmask]]On Behalf
Of David Cebon
Sent: Saturday, 27 April 2002 02:43
To: [log in to unmask]
Subject: Fwd: Determination/Monitoring of erosion below concrete
slabs/pavement s
Dear research colleagues,
After my question on how to judge a concrete pavement after 10-13 years in a
Design-Construct/Build-Maintain contract I gt quite a lot of suggestions.
However, in a brainstorm session we derived at the conclusion that we don't
have a real working system or equipment to judge the (remaining) structural
design life of the pavement after 10-13 years. Of course you can count the
number of cracks etc and even measure the deflections although these will be
very low but still you don't have or get knowledge about the situation at
the bottom of the concrete pavement. To complicate the problem it is
required that the concrete surface will be covered with a porous asphalt
layer (noise reduction). One major problem is possible existence of erosion
problems. When you see that the porous asphalt is very dirty by fine
aggegrates or that trucks are pumping this out of the pavement you are
already too late.
Therefore I would like to ask your attention for the following question(s):
1. Do you know references in which the erosion process below concrete
pavements is monitored and which (ndt) equipment is used.
2. Do you have suggestions how to measure in a non destructive way a
quantity which can be related to the amount of erosion.
(Wave-speed/SASW || Ground Radar Penetration || Capacity
measure :: Relation with the density)
It will not be possible to carry out destructive monitoring tests but it
will be possible to build in something like a steel plate in the base below
the concrete pavement .
Looking forwards to your reaction and thanks in advance
Ad Pronk
Road & Hydraulic Eng. Div.
Rijkswaterstaat
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