60 | CONCRETO & Construções
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Figure 12
Detail of the micro-milled surface and view of the motorway in Leon,
Spain (IECA)
5. OTHER LOW-NOISE SURFACE
FINISHING TECHNIQUES
5.1 Longitudinal tining
In the U.S.A., other finishing tech-
niques are used as well. In many states,
fine longitudinal grooves are applied to
the fresh concrete with a comb. This
also produces good results in terms of
noise and skid resistance, as long as
the process is carefully applied. This
technique is not being used in Europe.
5.2 Micro-milling
Micro-milling (or fine milling) is
a surface restoration technique us-
ing conventional cold mills of which
the cutting teeth are more closely
spaced on the milling drum.
Although it is mostly used on sec-
ondary roads, micro-milling can be
an alternative on motorways as well.
This was the case in Leon (Spain).
Acoustic characteristics have not
been measured but based on earlier
trial sections in Belgium, the rolling
noise level is about 1dB higher com-
pared to a diamond ground surface.
5.3 Diamond grinding
The technique of longitudinal tin-
ing of the hardened concrete, known
as “diamond grinding” is also often
used. This technique has already
been used frequently in several
countries for the restoration of ex-
isting concrete surfaces. This can
result in tyre-pavement noise levels
that are even lower than for exposed
aggregate concrete.
In 2009 a trial section in CRCP was
built in Germany, the “Geseke access
road” pilot project, in order to inves-
tigate the different surface character-
istics of the diamond ground texture
(Ref. 12). The surface was finished
with a longitudinally aligned ground
texture whereby two different groove
spacing distances (blade spacing 2
mm and 3 mm / blade width 3,2 mm /
grinding depth 3mm) were implement-
ed. Measurements with the CPX-trail-
er revealed excellent results : as low
as 94,9 dB(A) for the 2mm texture.
Repeated measurements in 2013
showed virtually unchanged noise lev-
els (95,2 dB(A)), confirming the high
durability of the ground texture.
5.4 Next Generation Concrete
Surface (NGCS)
In the U.S., the International
Grooving and Grinding Association
(IGGA) has developed a smoother
and even quieter surface, socalled
“Next Generation Concrete Surface”
(NGCS). A thin layer of concrete
surface is removed through the
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Figure 13
Detail view of the diamond ground surface and texture of the “Geseke
access road” in Germany (S. Riffel (2014))
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Figure 14
“NGCS” (International Grooving
and Grinding Association)
