DIGEST 2006 - Sabita

easily formed and shaped where
necessary. To date no problems
have been noted with the
pavement, and no subsequent
rutting or movement of the
asphalt has been observed.
Also no “slumping” and bleeding of
the mix in transit was observed as
was normally the case with these
long haulage paving projects. This
feature resulted in real savings as
bleeding would have damaged the
insulating materials.
It was evident that the road
authority had widened the working
window of asphalt in Broken Hill
by another four months, which has
“paved the way” for an extended
programme next year. The trial
was an outstanding
success, with both
the subcontractor
and the road
authority impressed
by the performance
of the FT
wax-modified
asphalt.
Boral Asphalt noted
that FT wax
modification
provides a practical
and economical
means of
significantly
increasing the range of products
available from our regional asphalt
plants, while still providing a
quality product for the client.
Durban freeways
The addition of
FT wax lowered
the mixing and
compaction
temperature
by 20 0 C more
than would
otherwise have
been possible
road closures. Work on the
Southern Freeway Phase 2 and 3,
as well as on the Western Freeway
Phase 1 and 2, recently benefited
from the use of FT wax modifier.
The project team had great
difficulties with thin surfacing work
(25 mm wearing course)
scheduled to be laid at night in
conditions falling ambient
temperatures as winter
approached. It proved impossible
to meet the asphalt specifications
using the specified modified binder
within the allowed construction
window, as only day time work on
Sundays produced satisfactory
results.
Penalties
The impending
penalties for delays
prompted the
supplier, National
Asphalt, to use their
extensive
experience with FT
wax to persuade the
client to allow a trial
section with this
modifier. The
results showed that
work could be
carried out at night and during
winter time since the addition of
FT wax lowered the mixing and
compaction temperature by 20 0 C
more than would have been
possible using the specified
modified asphalt.
The Southern and Western
Freeways of the Durban Metropolis
both carry heavy traffic loads
offering very little opportunity for
The client approved the use of FT
wax for the remainder of the
projects.
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