By Dwight Walker, P.E.
In our current tough economic times, both contractors and government agencies are aware of the importance of quality construction to pavement performance. They are looking for construction equipment which makes it easier to build smoother, better-compacted pavements in an efficient manner.
Paving contractors are looking for in-process information as the paving is still taking place. They are working to produce longer lasting pavements, take advantage of bonus payment provisions and avoid deductions. They need high production equipment that minimizes traffic disruption and holds their production costs down.
Agencies and owners are utilizing innovative equipment and some agencies are actually specifying the use of Intelligent Compaction (IC) equipment. For more information on the latest in intelligent compaction, see page 22. The information listed below is intended to provide an update on some of the new asphalt construction equipment available. Inclusion here is not an endorsement of a particular brand or methodology.
Bergkamp Inc., based in Salina, Kansas, manufactures a full line of truck-mounted, trailer-mounted, continuous slurry seal and micro-surfacing pavers and equipment.
Slurry seal and micro-surfacing is a mixture of aggregate, cement, asphalt emulsion, water and additives that are applied in a smooth layer over an existing pavement to extend the surface life. Slurry seal uses an unmodified asphalt emulsion which requires evaporation and takes several hours to set up. Micro-surfacing uses a polymer-modified emulsion which produces a chemical reaction to force the moisture out and sets in about an hour.
Bergkamp’s M1 continuous paver uses mobile support units to feed the paver with ingredient materials. Their new Electronic Mix Control and Diagnostic (EMCAD) System electronically controls production and sends constant feedback to the operator. The system ties material ratios of aggregate, asphalt emulsion, water, filler and additives together with an electronic signal and automatically maintains the ratios. It displays current and average material ratios, total material used and material application rates.
Located in Kewanee, Illinois, Bomag Americas is a part of a worldwide manufacturing and marketing organization that includes facilities in the US, Germany, Italy and China. Bomag offers a full range of single- and tandem-drum rollers, pneumatic-tire rollers, compact asphalt pavers, recycler/stabilizers and milling machines.
While Bomag is best known for its compaction equipment, the product line has been expanded to include Gilcrest’s commercial paving machines and Fayat’s milling machines. Additionally, Bomag offers tampers, plate and trench compactors and walk-behind vibratory rollers.
Bomag is continuing to expand its offering of IC equipped rollers (15 models worldwide). The latest IC-equipped model is the 278-AD4, a 78-inch wide drum, heavy tandem roller with a perimeter frame. Bomag’s IC system is called Asphalt Manager and is able to automatically change the energy coming from the compaction drum based on the reaction measured from the pavement layer. The system displays a vibration modulus value, EVIB, which can be calibrated with a density gauge.
Case Construction Equipment Inc., headquartered in Racine, Wisconsin, offers several models of single-drum soils, aggregate compactors and three tandem-drum asphalt rollers with drum-widths from 39 to 51 inches. In conjunction with Ammann, Case is developing an IC-capable roller.
Caterpillar Inc., in Peoria, Illinois, offers a range of asphalt paving and compaction equipment including pavers, compactors, milling machines and pick-up machines. Cat offers their AccuGrade IC system on their soils compactors, and it can be special ordered on asphalt rollers. AccuGrade includes GPS and measurement capabilities.
Dynapac USA Inc., located in Selma, Texas, provides a full line of construction equipment including tracked and wheeled pavers, pneumatic and steel-wheel asphalt rollers, soils compactors, plate compactors, and cold planning/milling machines.
Dynapac’s intelligent compaction asphalt monitoring equipment is called DCA-A for Dynapac Compaction Analysis for Asphalt. DCA-A, using GPS technology and temperature sensors on both drums, allows the operator to track the number of passes and displays the surface temperature of the mat. The contractor can use this information to analyze the rolling coverage and number of passes and to optimize the rolling operation. DCA-A is an option on Dynapac’s articulated tandem rollers and can be retro-fitted to older equipment.
E.D. Etnyre & Co., located in Oregon, Illinois, has a product line that includes asphalt distributors, chip-spreaders, live-bottom trailers and asphalt storage tanks. Their asphalt distributor offers one-person control from the truck cab with computer-controlled application rates. Etnyre builds custom-sized tanks for their distributors.
Etnyre also has chip spreaders with variable width spread hoppers. These variable width hoppers can adjust the chip spread width while moving and spreading aggregate. This variable width hopper capability is available in four widths from 9 to 18 to 12 to 24 feet. Application rates of asphalt and chips are computer controlled.
Etnyre’s asphalt transports are insulated semi-tank trailers that are designed to haul liquid asphalt products. Their transports range in size from 6,000 to 14,000 gallons.
Roadtec, located in Chattanooga, Tennessee, manufactures asphalt pavers, materials transfer vehicles, milling machines and soils stabilizers/reclaimers.
Roadtec manufactures 8- and 10-feet wide pavers in both wheeled and tracked models. Roadtec also makes the spray paver which combines tack spraying and mix laydown operations in one machine. Roadtec offers a paver option that can increase mat smoothness. Screed Boost manages settlement of the screed of rubber-tired pavers during stops. Roadtec now offers an improved grade and slope control automation system on its RX-500, RX-700 and RX-900 models. The SmoothMill digital automation enhances milled surface smoothness by automatically adjusting the depth of cut.
Roadtec’s new RT-500 Cold Recycler is intended to be part of a cold-in-place recycling train. The RT-500 is designed to crush and screen the RAP generated by the cold planer/milling machine. The on-board twin-shaft pugmill mixes emulsion into the recycled material at a rate up to 600 tons per hour. After mixing, the material is discharged into a windrow on the roadway.
Sakai America, Adairsville, Georgia, specializes in compaction equipment. They market rollers for asphalt, soils and aggregate. Sakai also has a line of light compaction equipment, including plate compactors and walk-behind rollers.
Sakai has two new highway-class asphalt rollers. The SW880 (79-inch wide drum) and the SW990 (84-inch wide drum) have some new features — the main one being a “cruise control” or auto speed which locks in the roller speed to a pre-selected number of impacts per foot. This allows the operator to move the FNR (forward-neutral-reverse) control lever into any forward or reverse position and the roller will maintain the specified impacts per foot. When the auto speed function is engaged, it prevents the operator from operating the machine too fast.
Sakai also has a new model, SW770HF, high frequency (4,020 vpm) double-drum asphalt roller with a 67-inch wide drum.
Sakai has added TransTech’s onboard mat temperature sensing system as an option.
Volvo Construction Equipment, headquartered in Asheville, North Carolina, offers equipment for all phases of roadway construction and rehabilitation — milling, grading, paving and compaction.
Volvo’s MT2000 milling machine has a half-lane wide cutting drum powered by a 610-horsepower engine. Three available engine speeds, selectable from the control panel, allows the operator to balance productivity, fuel consumption and sound level to specific job requirements.
Volvo’s 6000 series pavers feature ease of operation, improved materials control, a paver-mounted generator, and environmentally friendly cleaning. Automatic chain tensioning ensures the proper performance of the conveyor system, thus saving maintenance time and costs. Independent control of the auger and conveyor provides optimal control of material flow. Sonic sensors control each of the two auger and conveyor drives. Optional reversible augers and conveyors are available. A 30kW generator on all models electrically heats the screed and provides auxiliary power. The environmentally friendly coating system can be used on the complete machine and applied to the tracks with the push of a button.
Volvo’s asphalt compactors utilize their SMART drum vibration system to initiate compaction with the lead drum, followed by the rear drum, to increase compaction efficiency and avoid damage to cold material. Some models allow selection from eight amplitude settings.
Wirtgen America, headquartered in Antioch, Tennessee, consists of the Wirtgen, Hamm, and Vogele equipment lines. Wirtgen makes asphalt reclaiming and recycling equipment. Hamm markets asphalt and soils compactors. Vogele sells pavers.
Wirtgen’s W 150 milling machine can be fitted with three widths of milling drums, 4 feet, 4 feet and 3 inches, and 5 feet. The W 150 can cut to a depth of 13 inches.
Hamm has two new rollers, the HD+120 and the HD+140. These machines are articulated, tandem rollers with respective operating weights of 13.2 and 15.4 tons. Each of these rollers offers three choices of compaction methodology: (1) standard vibration in both drums; (2) vibration in the front drum and oscillation in the rear; and (3) high frequency vibration, 4,020 vpm. Hamm promotes the oscillation technology as a means of compacting without breaking aggregate or leaving roller marks. They describe oscillation as compacting by rocking the mixture back and forth rather than impacting it. Hamm’s new rollers can be equipped with the IC tools of a GPS and a stiffness indicator display.
The Vogele Vision line-up of asphalt pavers is available in 8- and 10-feet widths and both wheeled and tracked models. These pavers feature improved visibility for the operator. Self-diagnostics are monitored from a display panel, negating the need for daily checks. The latest asphalt construction equipment offers a variety of innovations geared to increasing production efficiency and pavement performance.
|Dwight Walker is a consulting engineer specializing in asphalt pavement materials and is a contributing editor for Asphalt magazine.|