49
july-august 2013
international
construction
MIXING TECHNOLOGY
Adding to the mix
From waste to profit
Ecogravel used on Italian motorway project
>
C
ontractor Tomat wanted to reduce its environmental impact by using Ecogravel
instead of basalt aggregates on a project to construct the third lane of the
Villesse-Gorizia motorway intersection in Italy.
Ecogravel is crushed slag that has been screened to remove residual iron. The
resulting material has the obvious benefit of a reduced environmental impact compared
to natural aggregate production.
One of the strengths of Ecogravel is said by asphalt plant manufacturer Marini to
be the reliability of the grading curve, while it is also very resistant to abrasion and
chipping. In addition, the fact that it is derived from a waste material of means that it is
generating a profit where there would have been waste.
The company chose a 200 tonne per hour Marini Top Tower 3000 to produce the
asphalt for the project. Designed for working in motorway conditions, all the plant’s
component parts including the aggregate cold feeders are positioned on metal
foundations on compact ground and are said to be well-suited to relocation along the
route.
The plant’s bitumen and fuel silos were fitted with an overflow tank to avoid spillage
in case of breakdown. The Top Tower 3000 also features insulated hot asphalt storage
bins as standard.
Marini said a production rate of 27,000 tonnes in six months was achieved, allowing
Tomat to complete the project on schedule.
Simem’s new Eagle series feature a concrete
production range of 60 to 160 m
3
/h and are designed
for easy transport with generic vehicles, as well as
installation without foundations
Astec has also introduced new technology in the form of a
diagnostic tool known as The Source. This is a hand-held device
that simulates most of the electrical signals coming into an
asphalt plant control system. It is said to help simplify plant
setup and troubleshooting.
Once asphalt is produced, storage can then become an issue.
Asphalt Drum Mixers (ADM) has tried to offer as much
flexibility as it can in this respect by introducing new stationary
and self-erect asphalt storage silos that are compatible with both
its own and competitor models of asphalt plants.
The storage silos receive freshly mixed asphalt from a conveyor
and keep it at a constant temperature until it is discharged. The
stationary and self-erect designs allow them to be used in various
asphalt plant configurations, and multiple capacity options are
available.
The capacity of ADM’s self-erect silos ranges from 30 to 75
tonnes, and stationary silo models hold between 100 and 300
tonnes of asphalt mix. All models are equipped with alarms to
alert operators when asphalt levels are
high, and they feature a fiberglass blanket
insulation to provide heat retention
while the mixture is stored. Optional oil
or electric heating systems are available
to ensure asphalt is kept at the desired
temperature.
All silos can be equipped with low
material alarms and LC1000 loadout
computers, which work together with
truck scales, weight batchers or reverse
(negative) weigh systems. The LC1000
allows operators to access truck loading
data, job files, silo inventory and more.
Concrete
On the concrete side there are new
developments focussed on increasing
the efficiency of mixing technology, and
recycling is also a key issue affecting
developments in this sector.
US contractor Hosea O Weaver and Sons plant invested in a
272 tonne per hour Unified counterflow asphalt drum mixer
from Astec. It found that the plant was able to consistently
run at 317 tonnes per hour without causing a problem.
