Canada's “Rock to Road” Magazine

September/October 2003 Issue

• Roadway design accommodates horse-drawn traffic
• Unusual compaction technique pays dividends
• New drill gives two for one performance
  
• Unique attachment improves efficiency, reduces equipment requirements
• Carden Quarry process improvements now a reality
• New granite quarry targets MTO approved sources list

For a copy of the issue that contains these articles with colour photos, click here.

Roadway design accommodates horse-drawn traffic

By Andy Bateman, Engineering Editor

    Few would expect horse-drawn traffic to be considered in modern road design and construction, but this roadbuilding job does just that. The Ontario Ministry of Transportation project is being completed by Guelph-based Cox Construction Ltd. and involves excavation, road widening and paving on a 12 km section of Highway 89 east of Mount Forest. Additional work under the same contract includes bridge widening and culvert extensions, new curbs and gutters, sewers and sidewalks for the village of Conn, as well as bridge repainting and culvert installation at other locations.
    Many of the design changes to two-lane Highway 89 take into account slow moving traffic, as this rural area's population includes Mennonites utilising horse and buggy transportation. (See sidebar on Mennonites). Up to now, dated road geometry such as blind crests and narrow shoulders has meant increased accident risk on a road shared by both modern and horse drawn vehicles. That will change with crest removal at a number of locations to improve driver's lines of sight, together with pavement widening throughout. The width of each paved driving lane has been increased from 3.3 m to 4.25 m (including a 0.5 m paved shoulder), while the gravel shoulders normally used by horse drawn vehicles have been widened from 2 m to 2.5 m.
     The main contract begins one kilometre east of Mount Forest, finishing just east of Conn. Valued at $5.5 million, principal subgrade, subbase and base quantities on this section include 112 000 m3 of dirt excavation, 70 000 tonnes of Granular B and 72 000 tonnes and Granular A road base.

Construction challenges
    Project superintendent Dan Dolby explains that there are a number of Environmentally Sensitive Areas (ESAs) adjacent to the job and these have presented their own challenges in terms of road construction. For instance, a completed stretch parallel to the South Saugeen River had a time window of just 10 days in which all embankment earthworks, drainage and seeding had to be completed. In addition, all embankment work on the north side was completed from above, over the existing safety barrier, as no machine access was allowed alongside the river below.
     Elsewhere on the job, environmental protection measures have included the excavation of several new creek beds, associated culvert extensions, erosion control, the installation of nearly 9 km of silt fence to contain surface runoff and the installation of mesh under embankment sod to inhibit slope erosion. These measures were certainly put to the test in the first half of August, when 193 mm rain fell in the area and necessitated some remedial work.
     In terms of scheduling, the job is being done in four 3 km long sections, with the volume of dirt moving reducing as the job progresses eastwards. Section 1, now complete, involved four major grade cuts, as does Section 2. Section 3 requires just one cut, while Section 4 requires road widening only. For safety reasons, cut sections must be excavated to a width of at least 7 m by the end of each shift to provide two open lanes for night traffic.

Earthmoving
     The majority of the dirt moving is in cut excavations and the excavation of new drainage ditches, with most the excavated material used to widen the pavement. The use of granular base materials depends on specific location: cut areas, once excavated to the required grade, receive a 600 mm lift of Granular B and a 150 mm lift of Granular A, with both lifts levelled and compacted prior to asphalt paving. New shoulders receive a 300 mm lift of Granular A, while pulverized areas typically receive a 50-75 mm lift of Granular A prior to fine grading and compaction.
     Dolby adds that once pulverizing begins on a particular 3 km section, the contractor has just 15 days to complete pulverizing and earth excavation as well as the placement of two lifts of asphalt in that section. A CMI RS-650, owned and operated by Roto-Mill Services, pulverizes and mixes some 90 mm of existing asphalt together with 100 mm -150 mm of existing granular A base. In this application, Dolby reports that the RS-650 unit has been completing a km per day of pulverizing for the full 6.6 m existing pavement width.
     Cox's extensive mobile fleet on this site included Caterpillar 325L and rubber-mounted Caterpillar 224B excavators on advance ditching and embankment construction. Volvo EC-360 and Hitachi EX 450 LC excavators were completing cut excavation, with typically 12 of Cox's Volvo truck fleet hauling away excavated material and bringing in granular base materials. Caterpillar D5N and D4H dozers worked behind the excavators to spread base materials for compaction by Svedala Dynapac CA 302 and Ingersoll-Rand Pro Pac 110 single steel drum compactors. Behind the CMI RS-650, a Caterpillar 140H grader completed initial grading of the pulverized material. In addition to the company fleet, a rental Link-Belt 3400 excavator, boasting an 18.3 m reach, completed slope trimming and ditching in those areas where creek beds and silt fences limited access.

Asphalt production
    Hot mix asphalt for the Highway 89 contract was produced by the company's portable plant, a Cedarapids E400P E Series Magnum CF counterflow drum mix unit with a rated capacity of 318 tonnes/h at 5 per cent moisture content. During production, virgin aggregates are conveyed from its four cold feed bins and introduced into the 14.64 m long by 2.54 m diameter drum by a patented slinger conveyor. RAP is added from a separate bin when recycle mixes are being produced, entering the drum's mixing chamber through a RAP entry attachment downstream of the burner flame. After mixing, coated material from the drum is elevated by an enclosed drag slat conveyor, first discharging into a 4.5 tonnes capacity slug feeder to reduce product segregation and from there into a 57 tonnes capacity portable product silo.
     In terms of combustion efficiency, the plant's counterflow technology provides control over hydrocarbon emissions such as volatile organic compounds (VOCs). Any VOCs produced by the mixing and drying process are incinerated as the gas is drawn through the burner's intensely hot combustion zone. In addition, the fuel efficient Cedarapids/Standard Havens DA110-100 dual atomizer combination oil / gas -fired burner has a patented atomization process for reduced carbon monoxide and nitrous oxide emissions. Measures to provide clean and quiet plant operation include extensive sound proofing and baffling around the burner, with burner access maintained by a tip up hood. Alongside the drum, the portable Magnum 10203 baghouse contains 948 sq. m (10,203 sq ft) of effective cloth area and is designed to filter 56 000 acfm of air at a maximum operating temperature of 1900 Celsius from the drum mixer at a 5.5:1 air to cloth ratio.
     According to the manufacturer, counterflow technology lowers exhaust gas temperatures, thereby increasing drum efficiency and reducing both fuel and maintenance costs. The aggregate feed system, incorporating the patented adjustable slinger, is said to provide precision placement of virgin materials, assists in the production of complex mix designs, provides accurate exhaust gas temperature control and reduces fuel usage through lower stack temperatures. On the asphalt cement metering system, a constant volume pump is also said to reduce maintenance, while a simple meter box eliminates mechanical stack-up pulse generators and compact design interfaces with any asphalt cement tank.

HMA paving
     Asphalt quantities on the job totalled 34,430 tonnes, consisting of HL4 binder mix containing 15 per cent recycled asphalt (RAP) and an HL4 surface mix utilising only virgin material. Hot mix was hauled from the pit based portable asphalt plant to the paving crew by the company's internal fleet, utilising Raglan 36-tonne capacity live bottom trailer units as well as conventional end dumps. On arrival at the site, the trucks discharged into the company's Cedarapids CR561R rubber tracked paver, equipped with a Stretch 20 electrically heated screed and Topcon's Smoothtrac sonic averaging system. Behind the paver, a Dynapac CC 501 dual steel drum compactor completed breakdown compaction followed by a Caterpillar PS 360B pneumatic roller in the secondary position. Once breakdown compaction was complete, the CC 501 looped back behind the PS 360B to provide final finishing of the mat.
     Subcontractors to Cox on the contract include Owen King Ltd. for bridge widening and Roto-Mill Services Ltd. for the pulverizing work.

Changes to Highway 89 are designed to improve visibility and widen the shoulders on a road shared by both modern vehicles and Mennonites using traditional horse and buggy transportation. Mennonites are members of a Christian sect who maintain principles similar to those of the Anabaptists; they baptize only after confession of faith and will not take oaths or undertake military or State service. Common occupations for Mennonites include farming and community service, with Old Order (Wisler horse and buggy) Mennonites found in five major settlements in Pennsylvania, Virginia, Ohio, Indiana, and Ontario.

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Unusual compaction
technique pays dividends

By Andy Bateman, Engineering Editor

    A rarely used rolling pattern and a new compactor proved to be the compaction solution for one paving contractor. ontario Ministry of Transportation Contract 2000 0227 involved the construction of 11 km of new four-lane highway to upgrade Highway 69 near Parry Sound. At $47.6 million, this contract was the biggest and latest part of a 30 km Highway 69 upgrade program and included seven bridges and a large box culvert in addition to new links to Highway 141 and local side roads. The general contractor on the job was the joint venture formed by two Ontario contractors, Bot Construction Ltd. of Oakville and E & E Seegmiller Ltd. of Kitchener, (Aggregates & Roadbuilding, April 2000).
     Hot mix asphalt tender quantities included 49 600 tonnes of HL4 modified and 27 600 tonnes of HL3 modified mixes, with mix designs completed according to conventional Marshall methods. All aggregates for the HL4 mix were site sourced and this presented some challenges to the paving team. The grading of the fine aggregates from these sources was not ideal, necessitating a relatively high stone content in the overall mix. Project engineer Marty Harris explains, " A mix percentage of 48 per cent stone by mass was required at the asphalt plant, compared to a stone content of between 43 per cent and 45 per cent for a typical HL4 mix. This increase in stone content was necessitated by the gradation of the virgin fine aggregate (blending sand), which was fine on the 600µm and 300µm sieves compared to a typical blending sand."
     Les Coulas, Seegmiller's asphalt superintendent, adds that the resulting coarse mix also meant a different approach was needed to achieve a smooth mat and compaction density requirements. Test patterns confirmed that the best results were achieved by reversing conventional rolling methods. Instead of the typical steel, rubber, steel configuration normally used for breakdown, secondary and finishing rollers respectively, Coulas settled on a rubber, steel, rubber set up.
     "The placing of a rubber-tired machine directly behind the paver provided the necessary kneading action to the coarse mix before its compaction by the steel drum units. Once on site, two steel drum units were used for mainline paving, with one unit used elsewhere. Rolling patterns were typically one pass for the breakdown unit, three passes (two vibratory and one static) for the steel drum units and one pass by the finishing roller. "
     Mainline paving comprised three asphalt lifts - a 50 mm lift of HL4 modified lower binder mix, a 40 mm lift of HL4 modified upper binder mix and a final 40 mm lift of HL3 modified surface mix. Ramps received one lift of 50 mm HL4 and one 40 mm lift of HL3, while sideroads received two lifts of HL4.
     Machines used for compaction included Bomag BW 20R pneumatic units and, new to Seegmiller this year, a Bomag BW 205 dual steel drum compactor. According to Coulas, the BW 205's productivity enabled the number of passes in the secondary position to be halved compared to previous units. Factors cited for this performance included the 205's amplitude and frequency capability, as well its digital readout of mat surface temperature. "The temperature display was utilised to keep the compactor within a specified range of travel on the mat. As it approached the paver, the operator monitored the increase in mat temperature until it reached 170° C. At this point, the direction of travel was reversed to prevent any tearing of the mat. At the other end of its travel, the machine travelled only to the point where the mat had cooled to 100° C to maintain efficient compaction."
     The bottom line was the achievement of all bonus goals by the contractor for a smooth, well compacted mat.

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New drill gives two for one performance

By Andy Bateman, Engineering Editor

    A new drill rig is delivering two-for-one performance at an Ontario rock quarry. Bought earlier this year, the new rig has gone into service at the Mara, Ont. quarry of James Dick Aggregates, located 135 km north of Toronto. This limestone operation is the source of a broad range of clear and granular sized aggregates shipped to customers in both the local and Greater Toronto Area markets.
     The Atlas Copco ROC D7-11 cab unit is currently on blast hole drilling in the quarry's evenly bedded upper Bobcaygeon formation bottom bench, where it has replaced two rigs on blast hole production. Like the previous units, the ROC D7-11 is drilling 76.2 mm diameter holes 11.9 m deep to provide 0.31 m of subgrade drilling in the 11.6 m high face. The blast pattern drilled here is square, with burden and spacing each set at 2.44 m. Quarry foreman Hank Wynstekers explains that blasts are completed daily to minimise impacts to residents in the nearby village of Gamebridge. As a result, individual blasts are relatively small at about 5000 tonnes, with each hole yielding about 200 tonnes and a typical blast size of 25 holes. In this application, drill operator Neil Berry reports that new rig is averaging 85.4 m/h on blast hole production, a figure that compares favourably to the combined average of the previous two units.
     After the holes for a shot have been drilled, the bottom of each hole is charged with one 50 mm x 400 mm stick of Dyno Nobel's Unimax dynamite followed by 0.31 m of water resistant ANFO (Ammonium Nitrate Fuel Oil) and 0.31 m of regular ANFO. Three 50 mm x 400 mm Unimax sticks are then added to deal with a local seam of hard rock, followed by the main 6.41 m ANFO column charge. Finally, each hole is capped off with 1.83 m of clear stone stemming. Non-electric 25/500 millisecond delays provide a delay of 25 milliseconds between the Unimax primer charges within each hole and 500 milliseconds between adjacent holes.
     Manufacturer's data indicates that the ROC D7 has a recommended hole range of 64 -115 mm and a maximum hole depth (utilizing T38, T45 or T51 drill steels) of approximately 28 m. A new boom system, said to provide optimum drilling efficiency, utilises the manufacturer's aluminium feed beam and cylinder feed system. The feed in turn carries Atlas Copco's COP 1800-series (top hammer) hydraulic rock drill having maximum impact power of 18kW and maximum torque of 980Nm.
     Modular design of the rig's air, hydraulic and electrical systems is said to facilitate the replacement of any necessary spare parts, while all hoses and electrical cables are tag labelled for easy identification. Boom variants include single or folding on both cab and no cab version. Hill climbing ability is rated at 20°, increasing to 30° with an optional winch that reportedly secures the rig and operator in difficult terrain. A Caterpillar 3126B engine delivering 149 kW at 2200 rpm provides power.
     A computerized version of this rig, the ROC D7 C, features a system that adds rods into the drill string automatically, said to increase production capacity by up to 15 per cent. Here, the operator sets the hole depth and automatic feed alignment and initiates the drilling. The ROC D7 C then completes the hole. ROC Manager software is said to provide monitoring and optimizing of the drilling operation and allows the remote exchange of information between rig and office computer. Drill plans can be designed in the office and sent to the rig, while hole deviation and other drilling data can be analysed in the office as drilling progresses. On board the rig, Rig Control System (RCS), senses variations in rock conditions and adjusts drilling functions. This system is said to deliver smooth and accurate drilling, including smooth ramp-up between the end of collaring and the start of drilling, while minimizing the consumption of rock drilling tools.
     James Dick Aggregates is a division of James Dick Construction Ltd. which is headquarted in Bolton, Ont.

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Unique attachment improves efficiency, reduces equipment requirements

By Andy Bateman, Engineering Editor

A specialized excavator attachment is helping a Nova Scotia company handle difficult materials while tying up less equipment.

    SRT Soil Remediation Technologies, part of the Dartmouth-based Conrad Group, acquired the attachment to improve the efficiency of the first and last stages in a multi-stage soil remediation process; the initial screening of excavated material and final turning of the remeditated soil in windrows. (See sidebar on SRT Soil Remediation Technologies).
     Conrad president Kim Conrad reports that the ALLU attachment has improved the effectiveness of both stages while allowing equipment requirements to be reduced. Previously, the incoming material passed over a conventional screen, with the screen fed by an excavator to provide an even flow of material. Even so, this stage was relatively inefficient and screen clogs were a common occurrence, particularly if the feed contained excess wet material. It also involved two pieces of equipment (the excavator and the screen) and their attendant costs. Now, this stage is completed by just the excavator/attachment combination and the attachment has proved effective in dealing with incoming material containing shale or clay oversize (+75 mm) lumps, wet sticky material, or a combination of both.
     At the soil windrow turning stage, Conrad explains that the attachment provides improved aeration and placement of the soil while avoiding any undesirable compaction. "The objective here is to introduce and retain air in the soil. Before, a wheel loader was used to place the screened material in windrows. Material placement was difficult, requiring the loader operator to discharge the material in a series of multiple small bucket movements in an effort to spread the material evenly. In addition, space limitations meant that the loader would sometimes have to travel over already placed material and compact the material under its wheel tracks."
     In appearance the ALLU attachment superficially resembles an excavator bucket. The resemblance ends there, as the bottom of the attachment is open and contains a series of hydraulically driven rotating drums fitted with discs and hammers to pulverize and size the material. After loading the bucket, the operator activates the auxiliary hydraulic controls to rotate the discs. Once all the fine material passes out of the bucket by gravity, any remaining oversize is dumped. The discs can be rotated in either forward or reverse at variable speed, with this movement powered by hydraulic oil pressure from the host machine and controlled by a cab-mounted joystick.
     Conrad's particular unit is mounted in face shovel configuration on a Kobelco SK 330LC excavator. Designated the SMH 4-17, this is a heavy-duty attachment, designed for excavators weighing between 28 000 to 34 000 kg. Equipped with 60 mm drums and a total of 96 discs, it has a volumetric capacity of 1.91 m3, a screening area of 2.0 m2 and continuous rated power of 100 kW. The 2450 kg attachment measures 2152 in width, 1559 mm in length and has a height of 1591 mm. Three types of hammers are offered, depending on the material being processed. Different models are available for light, standard and heavy-duty applications. Adaptors allow each model be fitted to a number of other machines including skid steers and wheel loaders.
     In addition to Conrad's application, the manufacturer claims a wide range construction materials applications for the unit, including the screening and crushing of construction waste, the crushing of reclaimed asphalt, lightweight concrete and other construction waste, the placement of screened pipe bedding material directly into a utility trench, the screening, pulverizing and blending any soil, the pulverizing of frozen materials, and regular soil processing as well as the stabilization of clay and contaminated soils.

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Carden Quarry process improvements now a reality

Aggregates & Roadbuilding visited Dufferin Aggregates' Carden Quarry this spring, when a number of process improvements there existed only on paper. Those improvements are now a reality, thanks to the successful completion of a major plant upgrade project. An in-depth report on the changes that have been carried out at the Carden Quarry was published in the May-June 2003 issue of Aggregates & Roadbuilding Magazine.

    Before the Carden Quarry expansion project began, theoretical improvements included a 10 per cent increase in overall plant throughput, an average 10 per cent increase in the ratio of clear sized products, increased flexibility in product mix, new finished product take off points and a reduction in overall plant operating and maintenance costs.
     Dufferin Aggregates' site supervisor Jason Lording reports that the project has delivered on all counts. Most important, overall throughput has increased from approximately 540 tonnes/h to 600 tonnes/h, when the plant is configured for 19 mm minus crusher run, rising to as high as 650 tonnes/h when the plant configured for 51 mm minus crusher run. In addition, the installation of a Metso HP400 cone crusher at the tertiary crushing stage has increased the ratio of clear sizes produced with a corresponding reduction in the amount of fines being generated. When the plant is configured for 5 mm crusher run, for example, the yield of clear sizes has increased by about 10 per cent. The Metso HP400 is the first every cone crusher utilized at this operation.
     Lording explains that the plant has been designed so that the cone crusher is always choke fed, with the replacement impact secondary crusher receiving the cone's overflow. Feed to the cone is controlled by adjusting the discharge opening on the new Cedarapids 5048 single horizontal shaft secondary impactor, which in turn affects the recirculating load from the plant's new Metso 7x20 triple-deck screen back to the cone. As planned, this screen is reducing load on the operation's existing finishing screens as well as providing extra product take-off points if required.
     In addition, the direct feed to the cone can be controlled by adjusting the position of the discharge chute doors on the plant's initial scalping screen - a Simplicity 8x20 triple-deck unit fitted with 89 mm opening punch plate, 57 mm and 25 mm Flex Mat screens on the top, middle and bottom decks, respectively. This overall arrangement not only enables the cone to be choke fed, but also enables the gradation of the material feeding the cone to be controlled. Lording adds that the replacement Cedarapids secondary impactor has increased crushing at the secondary stage.
     The Cedarapids unit is currently set at a 52 mm opening, but can be closed down to 25 mm if required. It is capable of taking up to 300 tonnes/h, although the load is usually lighter than this and dependent on whether the plant is configured for 19 mm minus or 51 mm minus crusher run production.

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New granite quarry targets
MTO approved sources list

By Andy Bateman, Engineering Editor

  Addition to the Ontario Ministry of Transportation's list of approved aggregate sources list is expected to boost business at a new granite quarry.

    Floyd Preston Ltd.'s new Mountain Lake quarry, located 140 km northeast of Toronto, is destined to be a key source of granite aggregates for the Greater Toronto Area (GTA), according to company president Larry Preston. The new operation's product range already includes large sizes for landscaping and dimension stone applications as well as a number of crushed products. That said, Preston is eager to see the quarry on the province's list of approved sources for Dense Friction Course (DFC) asphalt aggregates. If approved, the new quarry would become only the 15th such source, assuming no other changes to the status quo, and one of the nearest to the GTA.
     The approval process includes the use of Mountain Lake's aggregates in a DFC test strip on Highway 7A east of Port Perry this fall. In preparation for the test, the quarry's DFC aggregates have been shipped to the Bedard Sand and Gravel operation near Woodville and washed utilising Bedard's wash plant. Subject to successful performance over the stipulated two-year test period, the quarry will become eligible for the MTO approved sources list in fall 2005.
     Other aspects of setting up the new business appear to have been relatively straightforward, including the licensing of the property. Preston explains, "The property, on Lot 7, Concession 1 in Cavendish Township, Peterborough County, is in a sparsely populated area and we were able to resolve all operating issues with the few local residents and hunt camps. As a result, an aggregate extraction license, with no maximum annual extraction limit, was granted on the Crown property in late 2001 and the quarry opened for business last year. Access is also good, although subject to seasonal half-load restrictions, and utilises a forest road to access County Road 507. With its 25 million tonnes of quality Laurentian Shield granite reserves and a good location, we believe the business has a bright future."
     On the operational side, the focus at this early stage has been getting the new business underway while keeping capital costs down. For instance, all products are currently shipped to the company's Mount Albert depot serving the Richmond Hill, Newmarket and Aurora markets. Preston adds, "By using our existing depot as a transfer point, we have been able to avoid the up front cost of a scalehouse at Mountain Lake. We have also minimised equipment costs there by utilising contractors for drilling and blasting as well as crushing. Even so, our estimated start up costs are about $500,000."
     Suppliers to the new operation to date include MacNaughton Hermsen Britton Clarkson Planning Ltd. (site planning and reserves estimates), Cruickshank Construction Ltd. (drilling and blasting) and Robert E. Young Construction Ltd. for contract crushing.

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September/October 2003 issue

Aggregates and Roadbuilding Magazine
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