There are many strands to the latest developments in mixing technology for both concrete and asphalt, but they are united by the need to meet demand for more economical machines that are safe and intuitive to operate.
The big news in terms of asphalt mixing
technologies has been the development warm mix asphalt (WMA) processes
which allow producers of asphalt pavement material to lower the
temperatures at which the material is mixed and laid.
production temperatures of 140°C to 180°C for traditional hot mix
asphalt (HMA), today's warm mixes are created at 90°C and 150°C.
reductions have the obvious benefits of cutting fuel consumption and
decreasing emissions. In addition, engineering benefits include better
compaction on the road, the ability to haul material for longer
distances, and extending the paving season by being able to pave at
Marini - a subsidiary of Fayat - said two
main techniques for producing WMA have emerged. One involves the
addition of either solid or liquid bituminous binders, and the other
involves the use of additive-free foamed bitumen.
manufacturer is championing the foam route, and has developed the new
Aquablack foam generator which it claims is a low cost, emissions-free
device that can be easily installed on a metering line of a new plant or
a plant to be upgraded.
The Aquablack consists of three main
elements - an independent memory card, which manages production data, a
foam gun or online foam generator and a mass flowmeter equipped with an
The additive-free foam (consisting of hot bitumen
and 3% water on average) is created in the foam gun just before the
point at which bitumen is injected into the mixer. Using Aquablack
allows warm mix asphalt to be produced at 150°C, if not lower, according
to the company.
Other developments for both asphalt and concrete
mixing technology have centred on transportability and improvements to
plant controls and data logging technology as well as environmental
concerns such as emissions and noise.
Cemen Tech has developed
user-friendly controls for its concrete dispensers, and has introduced a
new style of control panel for its Mobile Concrete Dispenser line.
new panel is lighted for night time operations and incorporates
controls for the hydraulically powered water pump and the water flow
control valve directly at the operator's panel to make adjustments easy
In addition, water flow meters and admixture flow
meters are all centrally located in the panel for easy operation. The
panel also has a multi section hydraulic control valve which reduces
hydraulic hosing and allows for easier maintenance, according to the
asphalt side, meanwhile, Astec has also developed a new control system
for its plants. The PMIII system consists of individual modules for
burners, silos, motor controls, blending and loadout. The modules can be
installed together as a package or individually, allowing operators to
customise the controls at an asphalt facility.
Astec designed the
PMIII interface with minimal graphics on each screen so as not to
appear overcrowded, and the system has built-in diagnostics which are
said to minimise plant downtime by helping operators identify the source
of any problems.
Data logging is another area of focus for
Astec, which has also launched the Data Acquisition System Hub (DASH),
which is compatible with the company's TCII, PMII and PMIII control
This new system provides a real-time snapshot of
operations by gathering information from all plants, displaying it in
interactive charts and making it accessible via web browser, or flash
compatible devices such as Android tablets and smartphones.
data collected from each plant includes mix totals, raw material usage,
current production rates as well as moistures and mix temperature. Fuel
consumption can also be monitored for plants that have fuel meters
connected to the plant control system.
DASH also collects sales
data, which can be aggregated across plants to show totals shipped to a
job or sold to the same customer from multiple plants. The idea is to
speed up the resolution of any production problems, and allow management
decisions to be taken more quickly.
It has been a busy year for
Astec, whose other launches include a new V-Flight drum design as well
as a new portable asphalt plant. The company described its new drum
design as a "breakthrough", and said it would now be a standard
component on all new drums and made available as retrofits.
V-Flights are said to provide greater aggregate uniformity during the
drying process, resulting in better heat transfer, a reduction of fuel
use and increased productivity. Astec claimed that a reasonable
expectation for fuel savings on a high recycled asphalt pavement (RAP)
mix or open-graded mix would be about 10%.
Using the V-flights in
conjunction with an optional variable frequency drive (VFD) also adds
flexibility by extending the range of mixes that can be produced without
requiring that the flights be adjusted. With the VFD, a plant operator
will also have the ability to control exhaust temperatures regardless of
the mix design.
For the highest level of regulation, Astec is
introducing a stack temperature control system package that incorporates
the V-flights along with the VFD controls. This system automatically
modulates the drum speed to maintain a set temperature, and Astec
claimed it would allow customers to use more RAP in mixes as a result.
Dillman, a division of Astec, has introduced the portable 200 TPH
Dillman Voyager asphalt plant. The new plant is built around the Dillman
unified drum and includes a 50 tonne self-erecting surge bin to ensure a
quick set-up without the need for cranes.
Designed for producers
which require a plant made to move several times during the paving
season, the Voyager offers a straight-forward design with components
that can be dismantled, moved to a new site and set up and ready for
production in about five days.
type of highly mobile and flexible design is also reflected by other
manufactures. Lintec, for instance, has introduced a fully
containerised Gussasphalt plant - all the components of which (including
the mixer, burner, electrical cabinets etc) are pre-installed into
easily transportable containers, which have certified shipping
Gussasphalt is a very dense type of mastic asphalt
bound by a polymer modified binder. Lintec's latest plant, which has a
capacity of 20 tonnes per hour, was sold to French contractor Colas'
subsidiary SMAC in April this year.
Lintec claims that its
containerised plant design leads to lower transport costs and handling
times, with the plants up and operating after a week. No concrete
foundations are required as the large bottom area of the containers give
enough stability on a normal compacted site service, and the fact that
all the components are housed also lowers noise, dust and heat
Noise reduction has also been a central concern for
Ammann, which has developed a new silencer - the Ammapax - to help
contractors tackle this. The device, which does not require any extra
room as it is fixed to the chimney opening, is available in different
configurations that can reduce noise levels by 10 dB, 15 dB or 20 dB,
depending on requirements. It is also compatible with plants made by
Meanwhile, Ammann has also developed a new
module to add to its AS1 technology platform in asphalt plants - the
EcoView system. This technology is designed to show at a glance how
efficiently a mixing plant is working by continuously recording
operating and energy-related data such as fuel, electricity consumption
and CO2 emissions and presenting this in graphical form to the mixing
Comparisons with "previous performance" indicate trends
and any necessary need for action. The idea is to make energy costs per
tonne of asphalt as transparent as possible, and provide indicators for
possible causes of an increase in energy consumption.
also launched a new range of asphalt mixing plant - the Unibatch
models, which it describes as "all rounders". UniBatch plants have a
capacities range from 80 to 350 tonnes per hour and feature "future
proof" designs, capable of being modified to adapt to a wide range of
sites. The plants have a modular construction, with individual
components transported in standard containers, and the range is
compatible with all of Ammann's recycling technologies.
Asphalt Drum Mixers' (ADM) new EX Series of asphalt plants were also
developed to cope with recycled material and can process high
percentages of RAP. Capable of producing between 100 and 425 tonnes of
asphalt per hour, the EX Series use separate drying and mixing zones to
achieve the maximum level of heat transfer and fuel efficiency.
Series plants are available in portable or stationary versions and can
be operated by just one plant operator and one loader operator. ADM also
designed the plants to reintroduce emissions back to the drum's
combustion zone, making the plant more environmentally friendly.
has also broadened its range of asphalt plants with the introduction of
the new Top Tower 3000, which can produce 240 tonnes per hour and is
capable of a recycling rate of up to 35%.
The company said the
main innovation on the new plant concerned the upper part of the mixing
tower and the screen in particular. The idea was to upgrade the screen
and maximise the screening area (38 m² of total screening capacity and
6.6 m² for the sand screen), while keeping the dimensions down to a
minimum. In addition, the screen has been optimised with new access
hatches for quick and easy access to the different meshes, simplifying
Furthermore, the aggregate and filler
weighing hoppers on the Top Tower 3000 have been redesigned and
enlarged, mainly in response to the requirements of customers producing
special asphalt mixes containing high levels of filler, according to
Marini said its Top Tower models now offer a complete
range covering all outputs from 200 to 300 tonnes per hour. It said
each model is also capable of integrating the most recent technological
developments in terms of recycling solutions, including a recycling
ring, direct introduction into the mixer, combined ring and mixer
solution and parallel drums, as well as accommodating warm-mix asphalt
production, including the addition of foam bitumen, solid and liquid
additives and the injection of wet sand.
expect to see demand for such environmentally friendly plants increase
in the future, but not across all markets. As Ammann points out, plants
with recycling capabilities and reduced emissions are in demand in
markets where resources are tight and environmental requirements are
However, demand can differ significantly
from region to region, and Ammann said one of its key strategies would
be to improve its capacity to adapt its products to suit local customer
This tailor-made approach could become a decisive
competitive factor in the mixing sector, while the trends of increased
automation and transportability also look likely to continue to shape
Source- International Construction
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