31
november 2014
international
construction
ROADBUILDING
Project pressures
front, emulsion tanker truck, Roadtec RX-900e cold planer,
Roadtec RT-500mobile recycle trailer, a Caterpillar paver and
Caterpillar tandem and rubber-tyred rollers.
The RT-500 functioned like a material transfer vehicle,
providing a steady flow of recycled asphalt pavement (RAP)
to the paver allowing for continuous, steady production runs,
which resulted in smooth a pavement.
BR-381 is constructed with fine grain hard granite aggregate,
whichwas a challenge tomill.The contractor usedKennametal
teeth, whichwere replaced every two to three days of operation.
Themill typically cut 4.33-inches (110mm) deep and averaged
forward progress of 30 fpm (9m\min).
The emulsionpercentagewas adjusted from2.8% to3.5% and
the water was adjusted from 1.8% to 3.5% during operation.
However, the contractor added that on hot days the water
requirements could go as high as 4%.
BrownBrownmodified the paver hopper to add capacity and
installed sloped diverters to help prevent material build-up in
the corners. The hopper was also kept full to add weight and
improve the stability of the screed.
“The advantage of this style of CIRplant is thatmaterial from
the mill is directly deposited into the paver which appears to
help generate an improved surface finishon the newpavement,”
concludedMike Fischer, Roadtec field service technician.
New approach
And in-situ recycling is a concept that can also be applied to
reconstruction of deeper layers of highways. For example,
contractorNyoni Projects is taking a new approach to two road
upgrades in the NorthWest province of South Africa with the
use of two newCat RM300RotaryMixers.
“On both projects, we’ve noticed that the use of the RM300s
enhanced the speedatwhich layerswereprocessedandfinalised,”
said Nyoni Projects managing director, Maclaud Nyoni. “We
can do a 300 mm thick layer in one
operation, yet with graders we could
only do a 150 mm layer at a time. The
production levels from the RM300more
than trebledwhat one could achievewith
a grader team, yet manpower resources
remained the same, and other support
(water trucks) only doubled.”
The North West roads work is the
largest ever for Nyoni Projects. The
first North West section involves the
>
Lagos plant
Demanding requirements pointed toMarini UltiMAP 2000
I
n 2010 a five year planwas put in place to improve roads in and around the Nigerian
capital, Lagos. To help achieve this, a 180 tonne/hour asphalt plant was commissioned
in the suburb of Imota.
A key requirement was that the plant would be able to handle large amounts of recycled
asphalt pavement (RAP) and this dictated the decision to pre-treat thematerial in order to
control the quality of old bitumen and the size of recovered aggregates.
Accuratemetering of materials, flexible production (including the ability to produce small
batches), flexibility and frequent changes of mix (including coloured and fibre-enhanced
mixes) were also all requirements alongwith the need for efficiency and high production
standards.
This all led to the choice of aMarini UltiMAP 2000 in 2013 as the asphalt plant. Among
other key features, the unit offers 300 tonnes of bitumen storage in six tanks, allowing the
use of different blends.
ABOVE: Bloomsdale Excavating is using
13 Volvo full suspension A40F haulers
with K-Tec scrapers tomove 2.5million
m
3
of earth on a road building project in
Illinois, US.
LEFT: Nyoni Projects is using
Caterpillar RM300 rotarymixers to
speed up twomajor road rehabilitation
projects in South Africa.
