Versatile Europavers Find Specialty Niche in U.S.

High compaction at screed, beefed-up frames make larger Europavers suitable for placing stone, cement-treated base, and now specialty asphalt mixes like SMA.

by , Contributing Editor

Versatile, big Eurostyle pavers from two German manufacturers are carving out a niche with those contractors willing to take on specialty asphalt paving projects such as stone-matrix asphalt, or to place compacted road base, cement-treated base, or roller-compacted concrete.

Those contractors use them for their massive size and intense compaction at the screed not available from domestic-sourced pavers. High-energy compaction or tamping at the screed helps the Europavers achieve remarkable density and smoothness numbers, indispensible for attaining performance bonuses.

And at the small end, Italian-sourced pavers are helping a major manufacturer fill out its comprehensive paver line with pavers just right for commercial applications such as parking lots, bike or golf paths, or trails (see related sidebar).

First, anything but asphalt

The first Eurostyle pavers in the U.S. were not used to place asphalt at all, but to lay soil cement, RCC, CTB, and other stabilized bases. In Europe, the machines are used not so much as asphalt pavers, but more as  material laydown machines in which sometimes the material is concrete, sometimes SMA, sometimes foam mix, sometimes stone, and sometimes soil cement, with as much as 95% compaction behind the screed. Conversely, American-sourced screeds and pavers are incapable of achieving the kind of density required for those applications.

“The patented double-tamping technology from ABG is what contractors want for asphalt placement, but also for base and concrete applications, which is where most of these machines are being used,” said Brodie Hutchins, marketing manager, Large Paving Equipment, Ingersoll-Rand Road Development.

“These machines first came to America in the 1980s as base pavers for RCC, cement treated bases, and soil cement,” Hutchins said. “The Peltz brothers were pioneers in this application. Their claim to fame is placement of RCC and base products using ABG Titan pavers. They determined that double-tamping screeds are the best way to place bases, with accuracy to grade, no yield loss, and when the materials require it, compaction.”

In 2002, A.G. Peltz Group utilized an ABG Titan 423 paving machine for roller-compacted concrete placement for the reconstruction of Potato Creek No. 6 Dam, a 28-foot-high by 700-foot-long embankment built of local soils. To bring the dam up to Georgia Safe Dams Program criteria, a portion of the dam was converted into an overflow spillway which would take the place of the earth emergency spillway, using RCC to provide protection against erosion.

The design called for construction of a 330-foot-wide stepped RCC spillway over the center portion of the dam, large enough to allow the dam to safely pass major storm events. The project included placement of 4,500 cubic yards of RCC. During much of the RCC placement operation, the trucks discharged into a Morgan belt placer, which fed a conveyor from the crest of the dam.

The conveyor traveled along with the paver as it traversed the length of the new spillway. The paver placed 9-inch-thick lifts with a 9-foot-lane width. The use of the paving machine eliminated the need to form steps in the overflow section; instead, a special shoe was fabricated for the paver to create a rounded step edge. An Ingersoll-Rand vibratory roller was used to achieve final compaction of the RCC behind the paver.

Placing cement-treated base

On its arrival in 2003 from the factory in Hameln, Germany, an ABG Titan 326 EPM paver was taken directly by Moore Brothers Construction in Verona, Virginia, to place cement-treated base for new runways at Manassas Regional Airport. The job called for a 12-inch lift of cement-treated base at widths of nearly 19 feet, the manufacturer said. This unit was the first ABG Titan 326 paver to be used in the United States.

In 2004, use of Europavers to place road base got a novel twist in Europe, where a Joseph Vögele AG Super 2000 paver with AB 575 extending screed was used to place railroad ballast on high-speed track construction between Bern and Zurich for the Swiss State Railways.

For placing ballast, minor modification was required. Overlapping rubber plates were fitted onto the feeder bars of the conveyor in order to fully cover up the conveyor’s floor. From the augers several blades had to be removed in order to better handle the spreading of ballast. A spray system with separate water tank was installed in the machine to suppress dust while laying ballast. The screed was fitted in a position some 10 inches higher than usual and further to the back. Together with the paver, a smooth drum roller was on the job site to bring about the final density.

Europavers a niche product

In addition to these stone and base applications, Europavers are being used more and more to place hot-mix asphalt. But still they remain niche products, with only two major makers selling in the United States, both from Germany: ABG Titan, owned by Ingersoll-Rand Company; and Joseph Vögele AG, owned by Wirtgen Group.

In America, the ABG Titan models 525, 423, 8820, 326, and 325 are sold. “By and large these are all large, tracked pavers with double-tamping screeds,” Hutchins told Better Roads. “What drives the demand for these are their double-tamping screeds. The 325- and 326-class machines are the smallest machines capable of a double-tamping screed.”

Titan machine model numbers with the EPM suffix utilize Electronic Paver Management technology, in which the operators and screed operators consoles are run by computer. “One of the big advantages of the EPM systems is its easy diagnostics and trouble-shooting, with the opportunity to access the machine remotely via GPS and make changes,” Hutchins said. “All of the Titan tracked pavers are driven with EPM, and the next generation of wheel pavers will have it as well.”

These machines tend to be larger and heavier than their American counterparts, Hutchins said. “They have thicker frames, and their undercarriage is a steel product vs. a continuous rubber track. They are more robust and heavier than American machines, depending on the class of machine you are looking at,” Hutchins told Better Roads. “The ABG Titan 525 has 352 horsepower, twice as much as a 10-foot highway class machine in the U.S. They weigh a lot more; the 525, with screed, would weigh in the neighborhood of 70,000 pounds.”

The tractive power of the Europavers can be remarkable. In 2004, a Vögele Super 1900 paving an asphalt seal over a refuse landfill paved a 33% grade to the summit of the landfill without assistance, reported the manufacturer.

German environmental protection laws, for instance, stipulate a number of different impervious layers for the sealing of dumping grounds — from below prior to opening and from above after shut-down. For reasons of cost-efficiency, this job is increasingly done by road pavers.

Paving surface seal on dumping ground for refuse is not a simple job. Due to the steep slope, the paver normally works in a horizontal direction around the refuse heap while a heavy winched vehicle secures the paver. German contractor Kirchhoff paved the asphalt seal in vertical strips from the bottom upwards, with no time-consuming and costly securing of the paver. The standard-design Super 1900 of standard design was combined with an AB 500 screed in the TP2 version, and managed the steep slope all on its own.

In the United States, two models of Europavers are sold by Joseph Vögele AG, not to be confused with Vögele America Inc., a Chambersburg, Pennsylvania, manufacturer of U.S.-designed and built pavers, which also is owned by Wirtgen Group. These are the Super 1900 and the Super 2100, which are manufactured in tracked and wheeled models, but in the U.S. have been purchased only as track machines to date.

They utilize three screed models: a fixed, mechanical screed (not hydraulically extendable) the SB 300; and hydraulically extendable screeds with tamper bar and pressure bars, the AB 500 and AB 600. With bolt-on extensions, the maximum paving width of the SB 300 is over 52 feet, good for airport work; the maximum extendable width of the AB 600 is just under 30 feet. However, paving of that width is not done in the United States, which usually is no wider than 18 feet.

Yet another Vögele model, the Super 1800 SF, is used in the U.S. not to place hot-mix asphalt, but modified to place NovaChip open-graded friction course exclusively.

A shift to asphalt paving

Although the Europavers were first used for base work, as special asphalt mixes like SMA are specified, and as smoothness and density bonuses are offered, contractors are discovering the benefits of Europavers in placing today’s specialty mixes.

“Clearly there is a shift happening,” ABG Titan’s Hutchins said. “A growing number of contractors are using the Titan pavers principally for asphalt. They were designed to place asphalt at very high levels of compaction, and contractors are beginning to utilize this technology. They are able to use these machines on stiff mixes like SMA to achieve density and rideability much, much easier than they could with conventional American pavers.”

After years of looking beyond the American market, Joseph Vögele AG now is marketing its machines in the U.S. “The Super 1900 and 2100 machines are of interest to American contractors who are looking for more consistent densities, and higher levels of smoothness,” said Stu Murray, president of Wirtgen America Inc., Nashville-based distributor of Joseph Vögele machines.

“If the contractor just wants to go out and pave — and hope he gets paid for most of it — his mindset will never lead him to a European paver,” Murray said. “But a contractor who has faced the density specifications that states have been rigidly enforcing, the smoothness requirements that highway owners are insisting on, plus related penalties for not achieving one or the other, may be interested in such a machine.”

These big Europavers have awakened the interest of quality-conscious contractors, Murray told Better Roads. “It’s simple: American pavers have been the same mechanical ‘mousetrap’ for 50 years, and that’s especially true for the screed technology,” he said. “All of the paver tractors worldwide fundamentally are material transfer devices. Material is dumped from truck to hopper, it is conveyed from the front of the hopper to the back of the paver where it’s sometimes metered or otherwise flow-regulated. The material is dumped onto two augers, one which takes it to the right and one to the left. Every single paver on Planet Earth is built like that.”

The differences between pavers today lie in the screeds, he said. “Screeds follow a basic design,” he added. “They have some kind of vibration system and preliminary strike-off and screed plate. They’re anywhere from 18- to 30-inches wide. And they’re heated, and perform like a large iron which is towed by the tractor, and floats in relation to the tractor. There is a higher level of technology and thinking that goes into a screed designed today than persisted over the last 50 years.”

Interest spurred by tour

The new interest in European pavers in America for asphalt paving is a natural outcome of a landmark trip to Europe to study European asphalt paving techniques. This 1990 tour was the first contemporary International Scanning Tour undertaken by the Federal Highway Administration, and was co-sponsored by the American Association of State Highway & Transportation Officials, the National Asphalt Pavement Association, the then-ongoing Strategic Highway Research Program, the Asphalt Institute, and the Transportation Research Board.

“The objective was to exchange ideas and experience with highway agencies and the construction industry in Europe on design, production, and placement of asphalt pavements,” said then-Federal Highway Administrator Tom Larson. “We were particularly interested in the design of asphalt wearing courses, the use of asphalt modifiers and the benefits they offer to improve the durability of asphalt pavements — as well as recycling — both hot and cold. In addition, we were interested in contracting practices that would be innovative in the United States and cooperative public/private activities, not only in design and financing, but in research into new materials, methods, and machines.”

Working together, AASHTO, NAPA, and the FHWA selected a 21-member study group that included six AASHTO and eight industry representatives, as well as the TRB chair, the president of the Asphalt Institute, and two SHRP officials. Through cooperation with six government and industry representatives in Europe, a 14-day study tour of six countries — Denmark, France, Germany, Italy, Sweden, and the United Kingdom — was arranged.

“If the participants began with any chauvinistic ideas about the superiority of United States technology, they quickly realized we have a lot to learn from Europe about asphalt pavements and about pavement philosophy in general,” Larson said. “European pavements are better than ours and it’s no accident.”

Europeans built their pavement foundations better, he said. They used innovative surfacings such as stone mastic [matrix] asphalt, and utilized asphalt modifiers to a greater extent, and with better results, than in the United States. “Government and industry have a closer relationship — probably closer than would ever be possible in the United States — that encourages innovation and quality,” he said.

SMA, Superpave, and smoothness

“As a result of this tour, SMA came to the United States,” Murray said. The trip also spurred development of Superpave as an American durable asphalt mix. “It was felt with new gradation controls, new asphalt binders, new fines contents, gap-graded mixes, and cellulose fibers, Superpave and SMA could provide Americans with durable asphalt mixes that would perform well over the long haul. But Americans found the new mixes were difficult to work with. They had to be placed at higher temperatures, and they were harder to compact and get consistency. And everybody learned the hard way it was near impossible to get it smooth with conventional techniques.”

Over time contractors learned to work with hotter temperatures, get higher frequency rollers, get owning DOTs to permit different rolling patterns and specs, and developed a concept called the tender zone which helped achieve correct compaction of Superpave. Still, smooth pavements that would win bonuses were difficult to attain, Murray said.

“Highway contractors seeking smoothness and density bonuses sought equipment that could provide very smooth lifts, because given the extremely competitive nature of bidding these days, when a contractor bids a job, at least part of the bonus is bid into his cost,” Murray said. “He assumes he will get part of the bonus, and figures that into the bid price to undercut his competitors.”

After long-overlooking the U.S. market for asphalt paving, German manufacturers ABG Titan and Joseph Vögele AG have entered the American HMA paving market, with tractors and screeds that have worked for years placing SMA-type, gap-graded HMA mixes.

Compaction at the screed

“People in Europe learned that if you want maximum smoothness and consistent density, you have to get it at the screed,” Murray said. “You can’t get it with five or six, double-drum, high-frequency rollers that are making eight passes each to get density, but not leaving the mat smooth, and breaking aggregate while they’re at it.”

Murray says that it takes so much energy to move the HMA as it exits the truck, while pushing the truck, to place the asphalt at a uniform depth and width and density and smoothness, that the needed energy is best applied right at the screed, not after the HMA lies in place.

“For a long time, contractors thought that if additional energy was needed, they could just bring another roller or two or three onto the job,” Murray said. “In the last two years a lot of contractors have come to realize that putting that much energy into a mix 10 to 500 feet behind the paver is inefficient. Now they know why the Europeans have been developing big, heavy screeds with different energy systems in them. The ideal point at which to put the energy in the mix is the point where the mix is being formed and shaped to the right width and depth, because the material is hot, fluid, and is uncompacted. A screed with high energy can consolidate it, densify it, and smooth it in one, short process.”

Then the rolling process can change from being a breakdown-intermediate-finish process, to one which can concentrate on attaining optimum smoothness. “Now that the energy has been put in the mix at the screed, the compaction has changed from a breakdown and conditioning process, to a finishing process,” Murray said. “Now the contractor only has to bring 90 or 92% density up to 93 or 94%. He only needs two rollers, without high vpm or weights.”

Of course, there is a trade-off. With the added mechanics and hydraulics in the compacting screed, such a paver tractor-screed combination will cost more money. The tractors will be larger and heavier, with a heavier screed, but the power plant may have less horsepower than American pavers, principally because of the dramatically higher cost of fuel in Europe.

And with the added energy being placed in the mat at the screed, maintenance costs are higher for Eurostyle screeds, as opposed to American screeds. Other than that, the hoppers, conveyors, wear parts, augers, hydraulic motors, and pumps are essentially the same quality as found in the American pavers. “This combination still will be much cheaper than owning and operating two to three additional compactors,” Murray said.

Electric heat at the screed also has made the Eurostyle pavers more user-friendly than American pavers. Electrically heated screeds eliminate the smoking, the blow-torch effect beneath the feet of the workers, and the environmental mess generated by diesel fuel-heated screeds. But electric screeds have been used in Europe since 1960. “It’s old, old technology which is making its way to American-sourced pavers,” Murray said.

More on high-density screeds

ABG markets four versions of its high-density vibratory screeds. The fixed-width VDT 120 paves 9-frrt, 10-inches wide, and the VDT 121 paves 8-feet, 2-inches wide. The VDT-V 78 is hydraulically extendable from 8 feet, 2 inches to 16 feet, 5 inches, and the VDT-V 88 extends from 9 feet, 10 inches to 19 feet, 8 inches.

All four models feature ABG Titan’s dual vibrating tamper bars which, combined with their massive weight, allow the paver to achieve high degrees of compaction at the screed and, ultimately, notable smoothness. A VDT 120 used with an ABG Titan 525 paver produced 92% compaction at the screed recently in an SMA stone matrix asphalt project in Virginia.

ABG’s high-density screeds are available for Titan models 325 EPM, 326, 423, 8820, and 525, and also can be used on predecessor models of those machines. The high-density screeds are also recommended by ABG for paving roller-compacted concrete. “The benefit of the ABG double-tamper is in the fact that all of the compaction and proportioning is in front of the screed plate, as opposed to our competitors, which have rear-mounted pressure bars,” Hutchins said.

German-sourced Vögele pavers combine a tamper and one or two pressure bars to bring about a high degree of compaction at the screed. But even that is old technology, Murray maintained; Romans used tamper bars  hand held — to build their long-lasting roads.

More recently, Vögele High Compaction Technology is based on pressure bar(s) driven by pulsed flow hydraulics. These pressure bars bring about high compaction of different construction materials. These screeds are profoundly heavier than their American counterparts. Most will weigh 1,500 to 2,000 pounds more than a comparable American screed, although that weight may be spread out over a wider screed plate.

The tamper provides optimum precompaction of the mix, Vögele said. Driven by an eccentric shaft, the tamper bar packs the mix under the screed. Compaction by the tamper is followed by vibrating screed plates.

At the rear, one or two pressure bars provide high performance compaction at the screed. The pressure and frequency of the pressure bars is adjustable, based on the thickness and type of mix being placed. “All things being equal, a Vögele screed can achieve 88 to 90% density immediately behind the screed,” Murray told Better Roads. “A typical American paver with typical American screed and vibration on the same job and mix will get between 75 and 78% density. The difference between 78 and 90 is the additional energy that’s available in the screed.”

SMA and the Europaver

Driving the acceptance of the big Europavers is the growing popularity of stone matrix asphalt in the United States. SMA is a gap-graded (low medium-sized aggregate and fines) hot-mix asphalt design which brings together robust, coarse aggregate and as much as 6 to 8% liquid asphalt. Its lack of medium-sized aggregate — and fines percentage less than 15% of the aggregate weight — results in a strong mix with a rut-resistant, stone-on-stone structure which develops internal friction and resistance to shear.

But because the gap-graded SMA emphasizes large aggregate, the low-penetration grade asphalt conventionally used can drain out of the coarse aggregate structure. To keep the asphalt in place, cellulose fibers or other asphalt modifier are added at the plant to keep the binder in place. SMA is derived from the German term splittmastixasphalt, which was changed in the U.S. to stone matrix asphalt. The terms mean much the same thing.

SMA poses production challenges. Not all plants are set up to make SMA, and not all the aggregate suppliers are prepared to produce the stone necessary for SMA. In a recent Virginia DOT application, aggregates from 70 miles away were brought in for the mix. The liquid asphalt for this SMA mix was a PG 76-22, a polymer modified asphalt. Cellulose fibers were introduced to the drum while the SMA was mixed, and coarse aggregates represented about 80% of the mix by weight. Liquid asphalt was about 6.8% and the remainder was fine aggregates — a combination of mineral filler and dust — and cellulose fibers.

On this project, U.S. 17 in the vicinity of Fredericksburg, Virginia, a Vögele Super 2100 was used to place the SMA. “We really feel that paver is an excellent paver to place ride routes,” said Ron Burton, Stafford plant manager, Virginia Paving division of Lane Construction. “When we first got the paver in for a demo we took it out on a primary road where we used it to put down a 12.5-mm D mix, which has a non-modified PG 70-22 liquid asphalt. Behind the screed we were getting 98%-plus density. It was almost at the point that we felt we might be getting too much density on the mix, so later we dialed-back the pressure bar settings.”

For that test, Virginia paved half the road with a standard paver and half with the Super 2100. Virginia Paving conducts its own ride smoothness testing with its own rideability van, and it did a comparison on the two pavements. “There was a noticeable difference,” Burton said. “We would not use the Vögele everywhere, but when we have ride routes — projects on which we will be penalized or bonused according to the smoothness of ride we achieve — that’s the type of paver to put out there.”

“For SMA we’re getting compaction at the screed in the mid-to-upper 80s,” Burton said. “We have a good feel that what we’re getting behind the screed will allow us to get density with the rollers without having to literally beat the mix up, which has happened in the past. You have to get SMA density down with the paver, and then get the remaining density while rolling it out nice and smooth to get your rideability.”

Europavers boost smoothness

Yet another niche application for which the Europavers seem particularly suited is the repaving of motor speedways, either with SMA, or other bituminous mix. Invariably, an aged asphalt surface is cold-milled, and is replaced with a supersmooth asphalt driving surface placed with a Europaver.

Contractor Sunmount Corp. bought an ABG Titan 511 to place road base in the mid-1990s, but since has used it and a newer Titan 525 to pave noted race tracks such as the Texas Motor Speedway in the Dallas-Fort Worth Metroplex, and the Atlanta Motor Speedway. The firm recently completed its sixth race track paving job using the Titans, it was reported.

And in late summer 2004, the Indianapolis Motor Speedway was reconstructed using SMA following cold milling and track drainage improvements. Vigorous compaction at the screed was paramount for application of the SMA pavement, selected by the track and its consultant for its durability, strength, and impermeability under the punishment of professional race cars and tires, and weathering.

The screed of the Vögele Super 2100 was achieving 89 to 90% compaction as the material exited, followed by breakdown rolling in static mode, then unique oscillation compaction to 95.5% density, and finish rolling in static mode.

Smoothness requirements at Indy go way beyond standard highway benchmarks. “Our smoothness is hard to define, using the standard California Profilograph, even with zero blanking band,” said Kevin Forbes, P.E., director of engineering, Indianapolis Motor Speedway. “Our issue is with deviations which occur over 100 feet, which are significant to race car drivers. The typical Profilograph measures every 30 feet, so it won’t even pick our standard up.”

That’s not meant to demean what state DOTs do, Forbes said. “We don’t want to take anything away from state highways because they are very well constructed,” he said. “But it’s a different application of forces, and it’s different speeds. It becomes very, very critical that we give the drivers the smoothest, flattest, most predictable surface we can. If the drivers know the surface underneath them is very uniform, very reliable, and very consistent, that will allow them to pull out all the stops in terms of their ability to drive their race car.”

To ensure a smooth base for the SMA, the track was cold milled by a machine with 14-foot-wide drum. After a ramp-up period, later in the project the track was getting 92% density immediately behind the screed.

The Europaver was specified for its better handling of the SMA, Forbes said. “The three keys to density of SMA in our mind here are temperature, temperature, temperature. Getting that initial high density with elevated mix temperatures is a very good thing in case we have issues with mat temperature later on. And getting 89 to 90% density at the screed means that the heat we have in the mat will be retained for a much longer time. It means we will have more flexibility in rolling patterns behind the paver.” And those patterns are essential to a smooth mat.

Are Europavers slower?

Eurostyle pavers have a reputation for paving more slowly than American contractors will tolerate, and that’s thought to be a reason that it has taken so long for them to catch on for HMA work. The truth is they will pave as fast as an American machine, but in Europe, many elements combine for a slower job.

“Europeans have a saying about Americans,” ABG Titan’s Hutchins said. “They say Americans drive slow and pave fast, where in Europe they pave slow and drive fast. That hits the nail on the head; application and specs drive the speed of the job.”

“European streets tend to be narrower than American streets,” Wirtgen’s Murray said, “and asphalt plants in Europe produce at about 150 tons per hour and will be a batch plant. Job to job, asphalt lifts there are considerably thicker than U.S. placements. So if you are paving in downtown Munich, and you have a 150-tons-per-hour plant feeding a paver laying asphalt 3-inches thick, the paver is naturally going to go slower, only because of the circumstances surrounding the project.”

Similarly, due to the added available energy at the screed, it is easy for a swift-moving paver to move faster than the screed can transfer that energy into the mix. With intense compaction at the screed, it behooves the operator to go more slowly to make sure the at-screed compaction is done right. “To be able to get accuracy to grade with the screed tamping is much easier when the paver moves slowly,” Hutchins said.

Conversely in America, a corresponding job would be a wider roadway, an inch and a half thick lift, and a 400-tons-per-hour drum plant feeding the paver. “Those pavers will move faster,” Murray said. “We have had German-sourced pavers in Wyoming being fed by a 600-tons-per-hour plant, and they paved very successfully. It’s a matter of balance.”

But the best of both worlds may soon be upon the industry. At Conexpo-Con/Agg 2005, Vögele America Inc. will exhibit a high-horsepower, American-sourced 2219 T tractor, with an AB 600 T2 screed. “Because Americans like fast, high-horsepower American tractors, we will give them that, but with a high-energy German screed attached,” Murray said.

From Italy, Commercial Europavers from Bitelli

Italian road equipment maker Bitelli, of Bolonga, makes larger Eurostyle pavers competitive with Ingersoll-Rand ABG Titan, and with Joseph Vögele AG, but only their smaller machines are exported to the United States.

That’s the choice of Caterpillar Inc., owner of Bitelli, which uses the smaller machines as commercial-class pavers to round out its lineup of Caterpillar-branded asphalt pavers, said Francesco Grosso, area manager, Bitelli/Caterpillar Global Paving in Minneapolis.

In the U.S., Bitelli/Caterpillar sells the BB 621 C, an 8,800-pound track machine of 35 horsepower, and paving width of 20 inches to 9 feet, 10 inches; and the BB 632, a 13,900-pound wheel machine of 54 horsepower, and paving width of 25 inches to 13 feet using bolt-on extensions.

“Bitelli manufactures eight models of machines,” Grosso told Better Roads. “Its largest model is the BB 781, a 46,000-pound machine that is not sold in North America. We are selling the smaller machines in the United States because Caterpillar does not produce this size of paver in North America, and larger Bitelli models have a corresponding-size Caterpillar model.”

While larger Bitelli models are equipped with tamper-bar screeds, these two smaller paver have vibrating screeds, Grosso said. “There is a demand for tamper-bar screeds in the U.S., but it is very, very small,” he said.

For More Information

A variety of information is available on the Internet on today’s generation of Europavers.

Start at the Web sites of ABG Titan (www.ir-abg.com/eng/index.html) and Joseph Vögele AG (www.voegele-ag.de) for an overview of their products and applications.

The report of the very first FHWA-sponsored international scanning tour, the 1990 European Asphalt Study Tour — long out of print and unavailable — is available for download at http://international.fhwa.dot.gov/Pdfs/Eurotour.pdf.

An essential, 43-page publication — Designing and Construction of SMA Mixtures: State-of-the-Practice (QIP 122) — is for sale by the National Asphalt Pavement Association. Contact NAPA at 888-468-6499, or via e-mail at napa@hotmix.org.

The 2003 National Center for Asphalt Technology paper, Potential of Using Stone Matrix Asphalt for Thin Overlays, is downloadable as a .pdf file from the NCAT Web site at www.eng.auburn.edu/ center/ncat/reports/rep03-01.pdf. Visit NCAT’s home page at www.eng.auburn.ed/center/ncat/ for much more information on SMA, Superpave, HMA, and their applications.

The paper, Summary of Georgia’s Experience with Stone Matrix Asphalt Mixes, is available from the Georgia DOT Office of Materials and Research, as a .pdf file, at www.dot.state.ga.us/dot/construction/materials-research/b-admin/research/onlinereports%5Cr-SMA2002.pdf.

Also see Better Roads’ September 2003 Road Science article, Stone Matrix Asphalt is Catching on in the U.S. Access it on the internet at www.betterroads.com/articles/sept03b.htm.

Reprinted from Better Roads Magazine
March 2005

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