|
Canada's “Rock to Road” Magazine
July-August
2007 Issue
For a copy of the issue
that contains these articles with colour photos, click
here.
New
asphalt plant geared for b.C. growth
By Andy Bateman, Engineering
Editor
A
new hot mix asphalt plant is in pole position to take advantage of the
development boom in British Columbia’s Lower Mainland.
Officially described as “Columbia Bitulithic’s Port Kells
asphalt facility,” the plant is located some 35 km south east
of Vancouver, on the south side of the Fraser River and close to Golden
Ears Bridge project. The new set up includes a new stationary drum mix
plant, high capacity raw material storage, multiple feed bins, bag house,
finished product storage, control tower and truck load out, together
with a batch tower transferred from Columbia Bitulithic’s decommissioned
Coquitlam plant. Add extensive air and water quality protection measures
as well as noise reducing equipment to that list for an impressive example
of modern hot mix asphalt production technology.
Larry Howorth, the company’s general
manager of asphalt plants in the Greater Vancouver Area, explains that
the new location was selected to take advantage of current and projected
growth south east and east of Vancouver. “The plant is well positioned
to meet the increased demand for asphalt in Surrey, Langley and Abbotsford
south of the Fraser River as well as Maple Ridge north of the Fraser
on completion of the Golden Ears Bridge in 2009. Having both drum and
batch capacity provides full market coverage. High volume contracts
can be supplied from the drum plant while smaller volume retail business
or specialty mixes can be supplied from the batch plant. The batch plant
also provides winter operating flexibility. Here in Vancouver we tend
to keep our plants open pretty well all year round, shutting down only
a few weeks for winter repairs. On many of those winter days,
the batch plant comes in very handy for mixing smaller loads of the
various mixes, including cold mix, which is best produced in a batch
plant for safety reasons.”
In operation, aggregates arriving on site
are stored in one of six storage bays, each with a capacity of 5000
tonnes. Reclaimed Asphalt Pavement (RAP) will be stored separately in
a 2500 tonnes capacity bay. Material is recovered from these bays by
wheel loader to charge a bank of eight cold feed bins or four RAP feed
bins. Cold feed and RAP are conveyed to the plant separately, with both
conveyor systems incorporating a 4x10 scalping screen to pre screen
all feed material. Asphalt cement is pumped to the plant from one of
three 120 tonnes capacity tanks. The hot mix plant itself teams an Astec
Double Barrel drum mixer with a Phoenix Talon PT100 burner to provide
a nominal aggregate drying capacity of 363 tonnes/h. Within the drum,
feed aggregates are dried and superheated in the rotating inner dryer
drum of the plant. The heated aggregates then discharge into the stationary
outer shell of the plant where RAP, other additives and asphalt cement
are added as required, with mixing provided by paddles on the outside
face of the rotating inner drum. The resulting asphalt mixture is transferred
via a drag conveyor and a silo top conveyor system into four product
silos, each having a rated capacity of 270 tonnes, giving a total of
1080 tonnes of finished product storage. Underneath the product silos
are two 41.2 m long Pacific Industrial scales, with each scale served
by two silos. After loading, trucks pull forward to the end of the scale
where the driver collects a ticket from a remote printer and heads for
the job site.
General plant superintendent Reynold Amey
explains the thinking behind some key design aspects of the new operation.
“Having eight cold feed bins compared to the four to six of many
plants allows the mixing of an increased variety of aggregates. Some
of these may be the same size though from a different location and therefore
necessitating a separate mix design. This mix design flexibility is
expected to become increasingly important as aggregate supply tightens
and sources are changed more often. By the same token, having four recycle
feed bins where most plants have only one or two will allow increased
RAP usage through improved control of recycled asphalt cement and rock
being added to new mix. This makes good business sense, as higher RAP
content means significant cost savings from reduced virgin asphalt cement
and aggregate demand. Stockpile covers are provided for RAP, sand and
7 mm minus materials, that is, feed materials containing fine sized
fractions. These covers keep stockpiles dry, resulting in lower drying
costs. At the same time, the covers also help control fugitive dust
emissions, an area that is attracting increased regulatory scrutiny
in addition to odours and noise. On that note, the Greater Vancouver
Regional District (GVRD) required the entire site to be paved to reduce
dust emissions, a good practice in any case to eliminate mud tracking
or stockpile contamination in wet weather.”
The extensive list of environmental protection
measures continues. The asphalt cement (A/C) tanks are fully contained
(along with a 6000 gallon diesel tank) and their vertical rather than
traditional horizontal mounting conserves much needed space. Oil flow
to the plant is controlled by air actuated valves on the A/C tanks,
while vent condensers on the top of the each tank cool the exiting gases
so that hydrocarbons in the gas stream are condensed and drain back
down into the tank.
On the plant, variable frequency drives
on both the burner blower and the baghouse exhaust fan result in both
electrical savings and a significant reduction in the noise generated
by each component. As a result, it is possible to stand on the burner
platform and carry on a conversation at normal volume with the burner
firing at full capacity.
Both odours and volatile organic compounds
(VOC) emissions are minimized with the Double Barrel technology. The
exhaust system that evacuates steam and products of combustion from
the inner drum also evacuates steam and hydrocarbons from the mixing
chamber. These are pulled back through the aggregate dropout holes and
into the flame for incineration.
The air emissions permit that Columbia
Bitulithic was required to obtain from the GVRD included the company’s
own request for a permit that would authorize a maximum of 47 tonnes
of total emissions per year. By comparison, the Port Kells plant replaces
two older plants that are currently authorized to emit up to 330 tonnes
per year and current air emissions in the GVRD are in the order of 3.4
million tonnes per year, not including carbon dioxide. The plant will
be fired by natural gas, with low sulphur diesel fuel as back up in
accordance with the air quality permit.
The baghouse is fitted with micro-denier
capped Nomex bags providing much higher dust collection efficiency than
standard bags. As a result, the baghouse is expected to emit less than
20mg/m3 of aggregate dust, or 50 per cent less than the current maximum
outlet concentration requirement of 40mg/m3.
The plant’s silo-top blue smoke
package is designed to minimize odours and the escape of hydrocarbons
associated with the filling of the product storage silos. Instead, captured
hydrocarbons are ducted back to the dryer burner where they are injected
into the flame for incineration.
Surface runoff from the whole operation
is directed to an oil/water separator, sediment pond, and water treatment
system that chemically precipitates out and captures suspended solids,
and includes a specially modified 12.2 m cargo container for the flocculent
system. All run off water discharged from the site must be four times
cleaner than the nearby Fraser River is today.
Close attention has also been paid to
the production process, with mix production automated by a PC based
control system instead of panel mounted, push button control systems,
thereby bringing all of the plant’s controls onto one computer
screen. This system, together with closed circuit cameras at key process
points, give the plant operator close control over mix selection, production
and storage. During truck loading, the long scales mean that both tare
and gross weights can be measured live, as even trucks with pup boxes
are fully on the scale throughout the loading cycle. One scale is designated
for internal customers and the other for external customers to provide
faster service and trucking cost savings for all customers.
Now hidden, the plant’s design and
location also necessitated significant foundation works. Seismic (earthquake)
concerns meant engineering for and placement of a total of 56 piles,
some of which had to be driven to a depth of 33.6 m to support major
plant components such as the silos, liquid AC tank farm, slat conveyor
and drum mixer. The pile cap (concrete foundation constructed atop the
piles) for the silos is 15.25 m. x 12.2 m x 1.22 m thick while a 225
tonnes capacity crawler was required to lift the silos themselves onto
the foundation base plates. Despite these challenges, it took only 16
months from the beginning of the rezoning application to project completion
and plant start up, with an actual plant construction period of just
seven months.
Columbia Bitulithic is a division of Lafarge
Canada Inc.
Back to
top
U.K.
quarry show triumphs weather
Hillhead
– the world’s largest working quarry and heavy equipment
show - attracted a near record crowd despite the heavy rains that inundated
most of England in the weeks leading up to this year’s event.
According to show officials, total attendance at Hillhead 2007, which
took place June 26-28 was an impressive 18,500, slightly fewer than
the record-breaking attendance at the previous show in 2005.
The 450 leading international manufacturers
and suppliers who took part in the biennial event at Tarmac’s
Hillhead Quarry, near Buxton, Derbyshire, used 140 000 m2 of showground
space to exhibit their latest equipment, machinery and services for
the quarrying, recycling, heavy construction and related industries.
The largest working and static exhibit
was mounted by Terex Corporation whose various divisions introduced
a wide range of new products including five new Powerscreen machines
- the Chieftain 1700 and 2100X mobile screens, the Horizon 5163 mobile
horizontal screen, the Finesmaster 120 compact dewatering screen and
the Phoenix 3300 trommel. Terex’s Finlay unit used Hillhead to
demonstrate their newly introduced C-1540 cone crusher and to launch
the company’s new track-mounted 1-1310RS impact crusher. Also
on show was a new Finlay MP300 mobile wash plant.
Terex Pegson brought an array of their
track-mounted machines to Hillhead including an XA400 hydraulic-adjust
jaw crusher, a 1300 Maxtrak cone crusher, a 1412 Trakpactor and 1000SR
cone crusher.
The company also introduced its new XV350
track-mounted vertical shaft impact (VSI) crusher which represents a
collaboration between US-based Terex Canica and UK-based Terex Pegson.
The new machine, which features a Canica 2050 VSI packaged on a Terex
Pegson tracked chassis, can produce a range of fine products at capacity
of up to 318 tonnes/h. The 37-tonne XV350 is powered by a Caterpillar
C13 Tier III ACERT diesel engine that is rated at 440 hp.
Terex’s large two-storey hospitality
suite provided a viewing deck for visitors to watch two Terex articulated
haulers, a new TA30 with independent front suspension and a the top-of-range
TA40, being loaded in the adjacent demo area by a TC240 hydraulic excavator
and one of Terex’s new high-capacity TL450 wheel loaders.
Volvo CE took advantage of Hillhead 2007
to include a number of compactors, pavers and cold milling machines
from the newly-acquired road development business unit of Ingersoll-Rand
alongside their lineup of heavy and compact construction equipment for
the first time. Among the new Volvo CE machines at the show was the
50-tonne L350F wheel loader. The 6.2 m3 face loader, which replaces
the L330E, features the latest Volvo D16E Tier III-compliant V-ACT diesel
engine and a complete Volvo powertrain.
Another major Hillhead exhibitor was JCB
which showed the largest machine it has ever built, the 51.4 m long-reach
JS460LR hydraulic excavator. Featuring an Isuzu 305 hp six cylinder
turbocharged diesel engine, the JS460LR boasts an impressive 24 m reach.
JCB also showcased its range of heavy-duty machines and specialized
attachments tailored specifically for the quarrying industry. The machines
displayed comprised hydraulic excavators (including the manufacturer’s
flagship 46-tonne JS460), wheeled loading shovels, wheel loaders and
articulated dump trucks. A new Tier lll JS255LC excavator was joined
by a JS260XD demolition-spec’d excavator, 436 and 456 high-torque
wheel loaders and 722 articulated trucks in the working area for live
demos.
The Sandvik exhibit at Hillhead 2007 offered
visitors with their first opportunity in the United Kingdom to meet
the various members of the Sandvik “family” since it was
extended by the purchase of Extec Screen and Crushers Ltd. and Fintec
Crushing and Screening Ltd. at the end of April. Sandvik used four separate
stands at the show to display the company’s comprehensive range
of equipment and solutions for all stages of the extractive industries
from drilling, blasting and breaking, through crushing and screening,
to recycling and reprocessing.
Extec displayed a total of six machines,
including the new S-6 Doublescreen and C-10+ jaw crusher. The S-6 incorporates
a larger frame size, increased screen area and longer conveyors than
the previous S-5 model, while the C-10+ has numerous advanced features
designed to increase its versatility and durability.
Fintec unveiled its new track-mounted 1440 track-mounted impact crusher
which is equipped with a feeder and separate two-deck pre-screen. Powered
by a Cat C13 Tier lll-compliant engine and equipped with a Sandvik PR301D
horizontal shaft impact crusher with a feed opening of 900 mm x 1360
mm, the 1440 offer throughput of 300 tonnes/h to 350 tonnes/h depending
on the feed material. Fintec also introduced its newly redesigned 1080
track-mounted cone crusher.
Canadian aggregate machinery manufacturer,
McCloskey International Ltd. presented their 407, 512, 616 and 621 trommel
screeners as well as their 123, 302, Kompaq flatdeck and Minisizer vibrating
screeners at the company’s stand. Several McCloskey machines were
also part of the live demonstrations including the newest product, the
R155 High Energy™ three-way-split screener. According to McCloskey,
the 16x5 top deck and 15x5 bottom deck screen boxes offer a full 14.39
m2 of screening area for maximum production in heavy screening applications.
The R155 is designed to complement the company’s new S-Series
flatdeck screeners. The R155 can handle primary screening for feeding
a crusher while the S190 or S130 screen finished products.
Metso Minerals showcased their new LT60
track-mounted mobile crusher and ST458 four-way-split mobile screen.
The LT60, which forms part of the company’s newly upgraded range
of track-mounted mobile crushers, can generate up to 500 tonnes/h, while
the ST458 offers a maximum throughput of 400 tonnes/h.
Other major manufacturers exhibiting and/or
demonstrating machines at Hillhead 2007 included Finning/Caterpillar,
Komatsu, Liebherr, Atlas Copco, Hazemag and Cummins.
Established in 1982, the Hillhead show
is organized by QMJ Publishing Ltd.
Back
to top
Successful
B.C. quarry adapts to remote location
Adaptable
employees and a flexible production process are behind the long term
success of a remote B.C. quarry.
By Andy Bateman, Engineering
Editor
The
Jervis Inlet operation of Jack Cewe Limited is located on B.C.’s
Sunshine Coast, some 100 km north west of Vancouver and accessible only
by water. Location has certainly not prevented its solid growth however,
with 700 000 tonnes of aggregates shipped annually to customers in B.C’s
Lower Mainland, Alaska and other North American coastal markets. The
operation must also a strong contender for record distance shipped,
having supplied aggregates to a U.S. airbase on Wake Island, a Pacific
atoll located over 7000 km from the Sunshine Coast. Plant manager Mike
Dusenbury explains that the operation’s successful development
over many years can be attributed to two main factors; the people working
there and a flexible production process. For employees, cross training
and the ability to perform multiple jobs are the norm. On the process
side, a versatile set up allows a full range of aggregates to be produced
in response to changing market demands.
Officially known as the Treat Creek Pit,
the operation’s ability to produce a wide product range is due
in part to the availability of two distinct raw materials. A consolidated
granite outcrop and an unconsolidated granitic sand and gravel deposit
are both worked here, with key elements of the production process reflecting
the dual sources. A primary jaw crusher reduces shot rock from the quarry
as well as oversize from the pit, while a separate wash plant produces
a range of washed aggregates from the pit deposit.
Downstream of these two plants, the majority
of material processing takes place at the secondary plant, known on
site simply as the crusher and utilising material from jaw and wash
plants as feedstock. The secondary plant circuits integrate three screens,
two vertical shaft impact crushers and two flow control splitter boxes
to make a wide range of cubical (well shaped) products.
At the time of Aggregates & Roadbuilding’s
visit, raw material was being extracted from the quarry and pit at the
same time. In the quarry, drilling and blasting contractor Pacific Blasting
was utilising a tight blast pattern to maximise the yield of 89 mm minus
product for a specific customer.
After blasting, shot rock was loosened
and baled out by a John Deere 450D LC excavator before loading and hauling
to the plant. Meanwhile, pit run in the sand and gravel deposit was
being loaded a Caterpillar 988H wheel loader, with some pre-sorting
to cast out boulders larger than 750 mm. The pit run was then hauled
to the plant by two Caterpillar 730 articulated dump trucks (ADTs),
with a smaller Caterpillar D250 ADT added to the haul fleet when required.
At the plant, the trucks dumped pit run
into a feeder hopper with grizzly bars set at a 102 mm opening. Material
passing through the grizzly was conveyed to the wash plant where a Deister
8x24 dry screen first separated the feed at 25 mm. Material larger than
25 mm was conveyed to the secondary plant surge pile, while material
smaller than 25 mm was conveyed to the wash plant surge pile. Material
drawn from the wash plant surge pile was then directed over the wash
plant’s Deister 8x20 rinsing screen separating three washed coarse
sized products; 25 mm concrete rock, 12.7 mm washed rock and 4.8
mm birds eye stone.
The sand (minus 4.75 mm) fraction passing
the wet screen’s bottom deck was directed to a Kolberg computer-controlled
classifying tank producing concrete sand and a by-product sand, the
latter being used directly in dyke construction or blended into crushed
aggregate base. Back at the raw feed hopper, large pieces up to 750
mm retained on the grizzly were conveyed to a separate stockpile and
from there loader fed into the same Hewitt-Robins 3048 primary jaw that
was crushing quarry shot rock. The resulting 152 mm minus crusher run
was conveyed (together with the 102 mm x 25 mm material from the wash
plant) to the secondary plant surge pile.
At the secondary plant, material from
the surge pile passed over a Telsmith 6x16 double-deck screen from which
76 mm minus was stockpiled as finished product and 152 mm x 76 mm oversize
was conveyed to a Terex Canica 125 Vertical Shaft Impactor (VSI). The
76 mm minus well graded crusher run from the VSI was directed to a splitter
box. This splitter box allowed the plant operator to direct the material
to a second Telsmith 6 x 16 Telsmith double-deck screen separating 25
mm minus, a Deister 8x24 triple-deck screen or a combination of the
two screens.
Material going to the Deister screen was
separated into 9.5 mm crusher dust (100 per cent crushed), 25 mm crushed
clear and 12.7 mm crushed clear finished products and stockpiled. At
the same time, oversize from the Deister screen was directed to a Terex
Canica 2350 VSI. In this circuit, crusher run from the 2350 discharged
into a second splitter box which allowed the operator to control material
flow rates back to the Deister screen, the 125 VSI or a combination
of both. Material handling duties on site were completed by a Caterpillar
wheel loader fleet that included two 980G’s, three 988B’s,
a 966G, a 988H and two 980B’s. Excavation work was completed by
the John Deere 450D LC or a newly-arrived Hitachi 270LC-3 excavator.
Dusenbury adds that water-only access
certainly adds operational challenges that might not suit some. “With
no nearby communities, all our plant operators get here by crew boat
each day from a dock near the village of Egmont. So, whether it’s
a belt repair or operating a different piece of equipment, it’s
important that our people know how to keep things running. Over the
years, we have designed and built most of this plant ourselves and,
during that time, many of our operators have learned plant repair and
maintenance as well as equipment operation.
A similarly flexible approach is essential
for other people on site, such as our drilling and blasting contractor,
who may have to deal with special or new situations. In terms of supplies,
there is regular barge traffic leaving here with product and arriving
with supplies and heavy equipment on an as needed basis. However, deliveries
can take several days, so we maintain an inventory of critical spares
and consumables at all times. To illustrate the point, we have two 1000
kW generator sets plus two smaller units to supply electricity here,
as mains power transmission is not a practical proposition. To keep
those generators and all the mobile fleet running, we have diesel fuel
storage capacity totalling 48 000 gallons, or much more than would normally
be stored by an urban operation of comparable size.”
Similar adaptability is apparent in the
production process. The wash plant and secondary plants each have their
own surge pile of feed material to allow independent operation when
required. In addition, a number of the operation’s finished product
stockpiles are located over a long reclaim tunnel to facilitate barge
loading and final product blending if required. As a final process step,
a rewash screen circuit at the end of the product reclaim conveyor allows
certain products to be rewashed prior to barge loading.
At the secondary plant, the screen, splitter box and crushing circuits
provide a high level of control over the percentage of crushed surfaces
in the finished product. Dusenbury adds that other quarry operators
were highly sceptical when Cewe first installed VSI’s at the Jervis
Inlet location, expecting rapid wear rates in the abrasive granite.
However, these crushers have now been in service for several years and,
according to Dusenbury, deliver very good finished product shape with
few flats and elongations at reasonable unit wear cost.
The addition of the large Deister 8x24
screen into the VSI circuits was also a good move, as it has significantly
increased the production rates for smaller sized products. At the wash
plant, the current range of coarse and fine sized products contain only
natural rounds (absent any crushing) so are well suited for concrete
production. That could change with changing specifications if, for instance,
the operation was called upon to make a manufactured sand having 100
per cent crushed surfaces. In that event, the Jervis Inlet team would
no doubt find ways of adding crushing capacity to the wash plant circuit.
According to published industry literature,
VSI’s can deliver high output tonnage, portability, versatility,
cubical particle shape and accept larger feed sizes than other finishing
crushers, all at relatively low capital cost. Another group of producers
utilise VSI’s to beneficiate otherwise good deposits containing
soft or friable material. Like all equipment, some care is needed to
ensure the application is appropriate for a VSI. These crushers are
sensitive to oversize feed, tramp metal, and overspeed, all of which
can damage their hard but relatively brittle high chrome iron or tungsten
carbide wear parts. Contrary to popular belief, medium or higher feed
abrasiveness does not necessarily rule out the use of a VSI. Wear rate
is influenced by the silica content of the feed, the accepted guideline
of abrasiveness, as well as other factors such as moisture content,
impeller speed and tonnage.
Advance
sampling is always recommended to select the best crushing chamber for
a particular application and confirm that the cost of wear parts will
be reasonable. The Terex Canica 125 VSI at Jervis Inlet has a rated
maximum feed size of 203 mm. Its maximum throughput capacity and impeller
speed are 680 tonnes/h and 1050RPM respectively, with both dependant
on feed size. Recommended motor size is 700 hp.The somewhat smaller
Canica 2350 VSI has a maximum feed size of 152 mm and a maximum throughput
capacity of 544 tonnes/h. Its power requirement for maximum throughput
is 500-800 hp, depending on application.
Back
to top
Riding
the development wave
Paving contractors in
British Columbia’s Fraser Valley are being kept busy by the region’s
development wave.
By Andy Bateman, Engineering
Editor
Superior
Asphalt Paving Ltd. is a familiar name in the Fraser Valley contracting
world. This established mid-size paving contractor has 30 experienced
employees and, equally important, a solid reputation for quality paving
on commercial, industrial and residential paving contracts from facilities
in Langley, Abbotsford, Chilliwack, Maple Ridge and Vancouver. Superior’s
Harvey Lalli confirms that the company’s order books are being
kept full by the region’s solid growth which, if some of the latest
development statistics are anything to go by, seems set to accelerate
still further. (See Langley industrial permits break annual record in
six months).
Aggregates & Roadbuilding saw the
company’s crew in action on a recent commercial paving contract
in Langley. This particular job was located on Highway 10 in Langley,
where Superior was paving the forecourt of the new Wolfe’s Langley
Mazda dealership as subcontractor to Teck Construction Ltd.
Mainline paving crews in particular will
appreciate the challenges of achieving a smooth tight mat on a job with
runs as short as 5 m, frequent changes of direction, tight space, several
wedge shaped infills, hand work and numerous joints. Before paving,
the relatively deep base under the surface mix included 300mm of pit
run and 150 mm of granular base material. Lalli explains that base material
is typically laid to this thickness in the area to avoid soft spots.
Once the base material was compacted, hot mix asphalt supplied by Imperial
Paving Ltd. was placed and compacted to a finished thickness of 50 mm
by a LeeBoy 8515 conveyor asphalt paver. Compaction equipment working
with the paver included Ammann AV16K and AV12 tandem vibrating rollers
as well as a Caterpillar CB335E compactor.
Superior Asphalt Paving’s fleet
of four pavers from the LeeBoy range includes one 8816, two 8500’s
as well as the 8515 used on this contract. Specifications indicate that
the 8515 conveyor asphalt paver weighs 7.2 tonnes, has a 2.44 m to 4.6
m paving width and is powered by a 74 hp Hatz silent pack engine. Its
specifications include a 6.8 tonnes capacity receiving hopper, dual
914 mm wide conveyors and 305 mm diameter augers with sonic auger controls.
The heavy duty vibrating Legend screed is equipped with electric heating
as an option, while its 1067 mm front-mounted hydraulic screed extensions
are said to be easily adjustable to deliver a seamless mat. Manufacturer’s
data adds that cut-off plates enable varying paving widths as small
as 305 mm and as wide as 4.58 m. The 8515 is available with high deck
or low deck dual operator stations in which a joystick controls forward
and reverse electronically and the operator has electronic steering
controls from either side of the paver. Electronic mat control options
include single electronic grade control, electronic grade control, grade
& slope control and laser tracking. The heavier 8816 weighs 11.3
tonnes and is powered by a 130 hp Cummins engine. Its specifications
include a 9.1 tonnes capacity receiving hopper, twin 457 mm independent
slat conveyors and 356 mm variable speed augers with independent auger
and conveyor control.
Back to
top
The
value of intelligence
How documentation from intelligent Compaction
saves money - now and later
Success
and confidence are two entities that usually go hand in hand. Whether
it’s a football team, a multi-million dollar corporation or a
road contractor, very rarely does a person or group succeed without
first having the confidence to believe that success is possible. Conversely,
having overconfidence in a faulty premise can often lead to failure.
Contractors specializing in soil or asphalt
compaction could probably talk a lot about confidence and success, depending
on their individual experiences. What they might say is that confidence
comes in varying degrees.
Until recently, a contractor’s confidence
relied entirely on the expertise of a roller operator, in combination
with density tests taken from random positions on a job site. After
completion of several successful projects, a contractor’s confidence
would justifiably grow. But even with the best work done by the best
workers, there was simply no way to know for certain that optimum compaction
had been achieved over the entire area of a project.
From time to time, projects failed due
to improper compaction of a surface or sub-base. And in the construction
business, failure can mean having to redo small or large portions of
a project, leading to wasted time and expense.
It would be ideal for a person in any
profession to possess a tool that could help guarantee success. Fortunately
for contractors in the compaction business, there is such a tool in
the form of rollers with Intelligent Compaction systems. This technology
has just begun to take off in the United States in the past several
years, and for good reason, because it gives the contractor 100-percent
confidence that the job was done correctly. A closer look at Intelligent
Compaction will illustrate exactly why the system is so valuable.
Consistent, uniform
results
To fully appreciate the advantages provided
by Intelligent Compaction, it’s important to first understand
the fundamental differences that the technology presents in comparison
with standard rollers. Work on a job site begins much the same way with
or without Intelligent Compaction rollers. Both situations may involve
making successive passes with a roller over a test strip or test lane
of material. A nuclear or non-nuclear testing device is then used to
determine if the specified density for that particular job has been
achieved. But in terms of what the two roller types are trying to accomplish
with this process, the similarities end there.
When using a basic roller, the test procedure
is intended to define the maximum number of passes needed to achieve
proper compaction, with the assumption being that if there is no deviation
in the material and from that rolling pattern and operating speed, the
same end result will be achieved throughout the entire project. With
Intelligent Compaction, the initial control test is not performed to
establish a set number of necessary passes to be made, but rather is
used to determine an energy measurement that correlates with the specified
density to be achieved over the whole area.
As it moves along the work surface, an
Intelligent Compaction roller measures vibratory energy reflected from
the material being compacted. The energy numbers attained have a direct
correlation with density readings from a proven testing device. Most
Intelligent Compaction systems include some form of visual display that
shows stiffness measurements as the roller moves over the material.
All the roller operator has to do is achieve the same energy value from
the material over the entire surface.
A conventional roller isn’t able
to give any quantifiable feedback, so the operator must rely on observations
and experience to make compaction as uniform as possible. And in many
cases today, unseasoned roller operators are often forced into duty,
making it more difficult to achieve consistent compaction. Once the
job is complete, density tests are taken manually from randomly selected
positions. Because the testing is random, it is impossible to guarantee
uniform or proper compaction over the entire job site. Even if every
tested position was compacted properly, there’s no way of knowing
if soft spots exist in other locations.
This is in sharp contrast to an Intelligent
Compaction system, which monitors the compaction process consistently
over 100 per cent of the area that’s being compacted. Whether
it’s a 40-year veteran or a first-time roller operator, no guessing
is needed. The operator actually knows when proper compaction has been
achieved in any given location.
Smarter than the
average roller
Intelligent Compaction systems have the
ability to achieve consistent, uniform compaction because they are intuitive
machines. In fact, the design of the system requires that it be built
into the roller to function because it is the roller itself that monitors
the vibrational energy, or stiffness, of the compacted material. Material
stiffness equates directly to density. And based on the stiffness readings
that the machine receives, it will automatically adjust the output energy
that the roller’s drum is putting into the work surface. The roller
makes this adjustment through a process called vectoring, which involves
changing the angle of the energy delivered from the drum. For softer
areas, the drum will direct energy at a straight vertical angle. As
the material stiffens, the roller directs the drum’s energy at
a more horizontal angle, eventually becoming fully horizontal as the
surface reaches optimum compaction. By delivering the appropriate levels
of compactive effort into the material at all times, Intelligent Compaction
not only ensures that the required density is achieved, but also prevents
material from being over-compacted.
Over-compaction can be just as problematic
as under-compaction. Once the material has achieved maximum density,
continuing to deliver additional force can be destructive and cause
the material to lose density. The feedback from some Intelligent Compaction
systems will let the operator know that enough work has been done on
a given area. For other systems, the roller adjusts force automatically
even if the operator isn’t paying attention.
In addition to avoiding the damaging effects
of over-compaction, Intelligent Compaction also prevents roller operators
from wasting time in areas that no longer need attention. Knowing exactly
when to stop allows the operator to move on to another part of the surface
where further compaction is needed. For a contractor, this immediately
translates into cost savings for labour and fuel, and it also prevents
unnecessary wear and tear on the machine.
Intelligent Compaction rollers can expedite jobs even further because
the system’s design allows it to physically produce more energy.
Conventional rollers have a dual amplitude
system and are essentially limited to two different force values that
can be delivered. Only one amplitude is available on Intelligent Compaction
systems, but it is a higher amplitude that produces more force. Unlike
a conventional roller, Intelligent Compaction uses the vectoring process
to regulate how much of that force is actually delivered to the material.
The roller is not limited to one force value, but rather can adjust
to any value necessary.
In some cases, rollers with Intelligent
Compaction will produce up to 30 per cent more centrifugal force than
their counterparts without the technology. Putting 30 per cent more
energy into the material means achieving density about 30 per cent faster.
For example, a job that previously took 10 passes to achieve proper
compaction could potentially be completed in only seven passes.
Depending on the job and the material
to be compacted, the higher energy output provided by an Intelligent
Compaction roller could also allow for compaction of thicker material.
Being able to place deeper lifts in fewer layers is another way for
a contractor to save time and money.
With fewer passes required to compact
the work surface – or greater lift depths that can be placed and
compacted – Intelligent Compaction rollers can achieve the end
result much sooner, allowing the operator to move forward to other areas
of a project.
Standing by your work
The day-to-day cost savings that Intelligent
Compaction affords a contractor certainly help to justify the cost of
purchasing the more expensive system. But also important is what the
technology provides to the contractor well after the last day of the
job. Intelligent Compaction systems not only monitor the compaction
process for the purpose of adjusting to changing densities of the material,
but they also provide documentation of the work done over 100 per cent
of the project.
This documentation can be stored electronically
or printed on a piece of paper. The printout shows the travel speed
of the machine, the distance traveled, the force value produced by the
machine, and the compacted material’s vibrational energy reading.
But more than simply showing raw data, the information illustrates a
progression of compaction results achieved throughout the project. This
gives the contractor documented proof to qualify that the work was done
correctly in the event that other problems are discovered at a later
time.
In the case of a failed road, excavation
could determine the exact cause of the failure. If it’s found
that a certain area did not receive proper compaction, the contractor
could be held at fault if he can’t prove the job was done correctly.
If a roller without an Intelligent Compaction system was used, the only
available documentation is the random density testing from the site.
And if the failed area wasn’t tested, the contractor could be
held financially responsible for every aspect of the road’s repair.
The performance and accuracy of Intelligent
Compaction has earned the technology high credibility in the construction
business. Documented results from Intelligent Compaction systems are
widely accepted by departments of transportation at the federal and
state levels. In situations where a warranty issue comes into question
or goes into litigation due to some sort of later failure on a project,
contractors have the ammunition to show that their end of the job was
done correctly.
Value on many levels
A contractor’s job will never be
stress-free. With looming deadlines and unexpected setbacks, there will
always be some reason for concern. But Intelligent Compaction can alleviate
several of those worries and provide versatility in the process.
An asphalt contractor could utilize the
technology to test the density of an existing road or previously compacted
base before placing and compacting asphalt, providing further insurance
that a project will succeed. Intelligent Compaction also allows a contractor
to work in a variety of different materials and applications, creating
more opportunities for profit.
Getting good value out of a product isn’t
always easy. But Intelligent Compaction systems take care of this on
their own by providing the ability to produce improved, uniform results.
And the subsequent profits, labour savings and the insurance of documentation
all create direct monetary benefits for the contractor.
It’s these benefits and the end
result of proper compaction being achieved over 100 percent of the job
that make for a truly confident contractor. And with that full confidence
firmly in place, success is sure to follow.
Back to
top
Heavy
Construction Show reflects western growth
Billed as Western Canada’s
biggest show for the heavy construction industry, the 9th biennial Heavy
Construction Show was a big hit with visitors, manufacturers and distributors.
By Andy Bateman, Engineering
Editor
The
Heavy Construction Show targets those involved in construction, public
works and road maintenance, with the 2007 exhibitor list totalling 125
suppliers of equipment, accessories, wear parts and support services.
This approach certainly seems to be working, with show growth mirroring
strong industry growth in the Western Canada. Organizers report a 25
per cent increase in attendance for 2007, with a total of 5615 visitors
over the course of the two day event, held June 1-2, 2007 in Abbotsford,
B.C. The static part of this year’s show was held at the Tradex
exhibition centre at Abbotsford International Airport, while a simultaneous
live equipment display was held at the nearby “Demo Zone”.
According to its promoters, it is this two-shows-in-one format that
sets the Heavy Construction Show apart by giving visitors the opportunity
to both view and operate new equipment.
While some preferred to take a close look
at exhibitor offerings in the comfort of the Tradex exhibition halls,
excellent weather spurred most to take the 7 km shuttle bus ride to
the 25-acre Demo Zone. Here, visitors lined up to operate equipment
in a specially prepared terraced area that provided a good simulation
of working loose material in a pit or excavation application. With perhaps
40 machines working at any one time, the impressive outdoor show included
several excavators from most major manufacturer’s product lines,
with dozers, skid steers, ADT’s and special attachments rounding
out the action scene.
Back to
top
July-August
2007 issue
Aggregates
and Roadbuilding Magazine
4999 St Catherine Street West.
Suite 315
Westmount, Quebec H3Z 1T3
Tel: (514) 487-9868 Fax: (514) 487-9276
EMail: rocktoroad@sympatico.ca
|
