Mixing new roads. The need to improve traffic flow in an BITUMEN TECHNOLOGY

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1 Mixing new roads Special bitumen mixes and machines are capable of improving the service life of roads and reducing noise. Mike Woof and Patrick Smith report An asphalt pavement with a high modulus of rigidity was specified in Poznañ using Nynas Nypave FX25 PL bitumen binder The need to improve traffic flow in an important part of the City of Poznan, Poland, led to the decision to build a new 1.13km long dual carriageway. The route, known as Nowe Zawady, connecting the Sródka Roundabout with the crossroads at Prymasa Hlonda and Główna Streets, has a contract value of PLN40 million US$14 million). The client was ZDM Poznan and Poldrog Pila was the main contractor, asphalt producer and surfacing contractor. In view of the projected intense traffic flows, with a high proportion of heavy vehicles, an asphaltic concrete pavement characterised by a high modulus of rigidity (HMR, French class EME/enrobé a module élevé) was specified using Nypave FX25 PL bitumen binder. This binder, from the Nynas Performance Programme s Extra range, is specially designed for mixtures of HMR, and is in accordance with European standard EN and Nynas quality specifications. The design of a pavement characterised by a HMR is intended to provide base and binder courses of asphaltic concrete with exceptional qualities of load bearing, longevity and resistance to deformation, and also of resistance to thermal and fatigue cracking. For the Poznan link road, a number of mechanical requirements were specified for the pavement, including an integrated modulus of rigidity of at least 16,000MPa at 10 C; resistance to rutting of the base course, maximum 7.5%, and a resistance to rutting of the binder course, maximum 5%. A mix of asphaltic concrete was designed based on 0-16mm crushed basalt stone aggregate plus Nypave 25XPL binder, to ensure that the high parameters of the specification were met. The pavement comprises a binder course of 80mm above a 120mm thick base course. With noise limitation in mind, a 30mm thin layer surface course of stone mastic asphalt (SMA) was applied, containing Nypol 86. Compaction was carried out using two vibratory steel rollers of 10tonnes and 8tonnes respectively. The chosen solution (to use a pavement of HMR) meant that the base and binder courses could be reduced from the traditional 250mm thickness to 200mm while maintaining high load bearing capability, durability and longevity, plus resistance to surface cracking. ADVANCED OPTIONS Meanwhile, Italian specialist Iterchimica is continuing with its developments in the field of bitumen technology and is working on some innovative projects at present. The company has been playing a role in a project to build a new international airport in Oman, working with Greek and Turkish companies. April 2011 World Highways 27

2 BITUMEN TECHNOLOGY Alessandro Giannattasio, Iterchimica s deputy chairman, said: We got the contract for a technology transfer of polymer-modified bitumen (PMB). For us it s one of the most important awards. Our technicians stay on site for a year and we supply the know-how for the PMB. We have the responsibility for checking the mix design and the quality but this contract is not the traditional deal with a sale of chemicals. The project will see the production of some 50,000tonnes of PMB material over a two-year period from the Massenza plant, with Iterchmica s technicians continuously monitoring the output. Meanwhile Iterchimica has also been working for the last three years on a new type of fibre for use in asphalt. This project has been run in partnership with Milan University and uses recycled materials in the fibres, which are designed to increase the mechanical performance of the asphalt mixture according to Giannattasio. Another important development is the warm asphalt system the company is working on in partnership with the Fayat Group. This includes a liquid additive that helps reduce the mix temperature by 40 C to 120 C (and in some cases, as low as 95 C), with a major benefit in terms of reducing fuel consumption during production and emissions from the plant. Giannattasio said that the road authorities in Milan have now accepted the use of warm asphalt as this technology is well-suited to use in urban areas. The warm asphalt approach can even allow effective paving and compaction operations in colder weather, extending the road repair cycle throughout the year. The 700km A14, which connects Bologna in northern Italy with Bari in the south of the country, is being widened with the addition of a third lane and this will also feature the warm asphalt technology according to Giannattasio. The Sprayjet system can spray bitumen speedily and effectively, while reducing materials wastage searchable List of companies worldhighways.com Fayat Group Iterchimica Massenza Nynas Vögele CLEAN COURSE Munich s popular Haidhausen district, which carries heavy traffic volumes on its main thoroughfares, is benefiting from a new road surface. The low-noise, stone mastic asphalt (SMA) wearing course will reduce traffic noise for residents, an important factor in the choice of this high quality surface by the local authorities. The surface was laid with the help of a Vögele paver equipped with the company s sophisticated SprayJet system, and is one of several rehabilitation projects to reduce traffic noise in the city. To reduce noise, the number of joints in the asphalt pavement has to be minimised, although as the flow of traffic has to be taken into account when resurfacing a road the paving job has to be carried out in several narrow strips. Local contractor Franz Schelle was able to avoid this by taking advantage of an existing closure of a traffic lane on one road, and this allowed paving in just three strips along the full length of the 550m stretch. The disadvantage though was a cramped job site, separated from traffic by beacons. First, the team removed the old wearing and binder courses to an average depth of 135mm using Wirtgen milling machines, and a new binder course was laid. For paving the new wearing course of lownoise SMA, a Vögele SUPER fitted with an AB500-2 screed and a SprayJet module was employed. This equipment operated with a maximum spray width of 6m and the screed was set-up with bolt-on extensions. In this configuration, the spray paver placed a wearing course, 25mm thick. The contractor explained that in order to leave the noise-absorbing cavities in the wearing course, the mix cannot be compacted to the same degree as conventional asphalt: an effective solution to laying a durable wearing course with an optimum bond of layers is to use a spray paver. The SUPER with its SprayJet module spreads bitumen emulsion and paves asphalt in a single pass, delivering a high quality surface compared with the conventional method of spraying emulsion and paving asphalt in two operations, according to the contractor. Another reason for the efficiency of the Vögele SprayJet Technology is the cleanliness of the system, as the spray system is designed to maximise efficiency and minimise materials waste. The spray system operates at a low pressure of just 3bars to reduce the formation of mist and the device delivers the material in pulses that are controlled automatically. Because the emulsion is immediately overlaid with asphalt, it is not damaged by transport vehicles, feeders or pavers and ensures an effective bond. Using the SprayJet system for pavement rehabilitation is also said to be economical, as the wearing course is thinner than for conventional roadworks, and this can deliver material savings of up to 50% while allowing for fast working and reduced road closure periods. The SprayJet module can be fitted quickly to the SUPER when required and removed when it is not needed, boosting versatility and utilisation. 28 World Highways April 2011

3 Forklifts with front-axle loads of up to 110tonnes caused significant pavement deformation in section H8-K1 BITUMEN TECHNOLOGY Port debuts highly modified asphalt An authority replaces container wharf pavement damaged by forklift loads in world s first commercial use of high-performance asphalt base course. By Paul Fournier New Zealand s Port of Napier recently replaced a heavily deformed section of pavement in its Container Terminal with high-performance asphalt mix incorporating technology never before used in a base course. Higgins Contractors of Napier removed the deformed pavement from a section of H8-K1 and re-paved the area using Highly Modified Asphalt (HiMA) technology developed by Kraton Polymers. The technology employs hard bitumen modified with styrene-butadiene-styrene (SBS) polymer, Kraton D0243, and is designed to improve pavement resistance to permanent deformation and fatigue from repetitive loading. Such pavement qualities are essential at the section near the edge of Kirkpatrick Wharf where forklifts loading and unloading shipping containers have imposed extraordinary repeated loads that caused premature pavement failure. Built in 2001 and 2002 as an access road, the pavement was never designed to accommodate forklift front-axle loads of 110tonnes. Adding to the problem is the increasing number of container throughputs at the port, which have approximately doubled over the past ten years according to Clarke Curtis, senior engineering technician for the Port of Napier. Within a few years, pavement damage from this activity produced ruts up to 85mm deep with deformation in the base course alone exceeding 40mm. Furthermore, ruts were causing forklifts to shake, requiring the Port of Napier to spend more money on maintaining them. Port officials decided to have the pavement reconstructed, but they wanted a pavement that could stand up to high forklift axle loads over a design life of 20 years. At a meeting with Higgins Group, port officials approved the use of HiMA for the H8-K1 project. Sean Bearsley, product development manager for Higgins Laboratory, said the trial could have major ramifications for pavements subjected to heavy loads or pavements with asphalt layer thickness limitations. Robert Patience, Higgins group technical manager, designed the pavement structure and executed the H8-K1 project, removing the deformed section and re-paving it with HiMA technology in the base course and standard SBSmodified mix for the surface layer. This new pavement structure utilised 750mm of 4.5% Portland cement stabilised 0/40 crushed aggregate sub-base; 100mm of SP28 high modulus base course made using Kraton D0243 modified bitumen 40/50; and a 50mm SP14 surface course made using 5% SBS modified 80/100 bitumen. The base course was a continuous well-graded mix using six single-sized April 2011 World Highways 29

4 crushed coarse greywacke aggregate and one fine aggregate comprised of crusher fines or dust. No natural sand was used. The content of the 40/50 penetration grade bitumen for the base course was formulated to be 4.3% of the mix mass, with Kraton D0243 modified polymer comprising 7.5% of the bitumen. Until the development of low-viscosity Kraton D0243, such an elevated polymer content would not have been practical. While adding polymer to bitumen provides desirable benefits, generally as polymer content in bitumen binder exceeds 3% the binder viscosity increases, making asphalt mix gradually more difficult to produce in the plant and increasingly unworkable at the job site. However, through changes in polymer design, Kraton D0243 polymer content can be raised well beyond 6%, even in harder bitumens. At the selected 7.5%, no adjustments were needed at the plant or in the field for the H8-K1 project. On the day that Higgins paved H8-K1, the weather was damp and chilly, with ambient temperatures hovering about 8 C and winds of approximately 30km/hour. Since Higgins asphalt plant is located just 6km from the job site, there was no discernible drop in mix temperature as delivery trucks deposited the 160 C asphalt directly into the hopper of Higgins Vögele paver. According to Higgins Patience and Bearsley, mixing, paving and compaction went smoothly. They indicated that the asphalt mix team observed an unusually clean operation and not much difference in handling the high-performance base course mix in comparison to asphalt employing standard SBS modified bitumen. However, they observed that as the mix cooled rather quickly due to raw weather hand work became more difficult. Compaction was accomplished by two Caterpillar 7tonne doubledrum steel rollers and a Sakai GTW-750 pneumatic rubber-tyred roller operated in vibrating mode to improve consolidation of the mix and achieve the specified 4% air voids. A few months later, an opportunity arose for Higgins Group to pave another, larger, area of pavement covering an area of approximately 2,700m² at Loading Zone 1. The same type of mix was placed here as at H8-K1. Bearsley said the proof of performance of the two re-paved sections would be simple: the absence of pavement wheel path deformations over time. This article is reprinted with permission from Roads magazine, and a fuller version can be found at. Kraton Polymers As mix cooled rapidly in the raw weather, the crew operated the Sakai pneumatic-roller in vibratory mode to expedite compaction TAKE ADVANTAGE OF OUR MANY YEARS OF EXPERIENCE IN THE FIELD OF BITUMEN TECHNOLOGY TO THE ASPHALT SECTOR PLEASE CALL US FOR FURTHER INFORMATION ON: Bitumen Emulsion Plants Polymer Modified Bitumen Plants Micro Surfacing Pavers Pilot Plant Cold Mix Plants Emulsion Plant Mobile PMB Plant Control Panel AND LET US HELP YOU WITH: Bitumen Emulsion Technology PMB Technology Recipes Know-how Training Combined PMB/Emulsion Pilot Plant Cold Mix Plant Jellingvej 15, DK-9230 Svenstrup, Denmark Phone: Fax: enh@enh.dk Mill Unit 30 World Highways April 2011

5 Emulbitume s new Atomix E Developed in 1933 by the French engineer M Rouaze, the Atomix mill is now used by many customers across five continents and is able to make all types of emulsions including SBR [styrene butadiene rubber] and SBS [styrene-butadienestyrene]. French company Emulbitume, which says it is among those at the forefront of bitumen emulsion technology worldwide, has developed a new colloidal mill with a capacity of 6,000litres/hour (1,320 gallons). This new Atomix E is based on the same principle as existing Atomix units already manufactured by Emulbitume (B, A, D) but it will help to develop small mobile production units, offering the opportunity to be nearer to the job site, says Emulbitume. In future, energy savings and the reduction of transportation will be the priority of road constructors and these units can help them to develop a new strategy. The units can be containerised, electrically heated and fitted with all the standard options that EmulBitume offers to its customers. According to the company, the Atomix mill has many advantages including active leakproofness, even with modified bitumen; good and accurate particle size; easy and low maintenance costs; it can produce all types of emulsions requested by the market, and it is silent while running. Like the other Atomix mills, Atomix E has enough pressure at the outlet to send the emulsion directly to the storage tanks (no additional pump needed), and it is driven by a 15kW electric motor. Emulbitume, which specialises in the design, manufacture and commissioning of bitumen emulsions production units and macerator pumps, has over 30 years of experience in the bitumen emulsion and modified bitumen market with a presence in more than 65 countries and more than 250 units running. It offers a full range of products from units for laboratories to production devices, and to support its worldwide customers it offers technical support (research and design office together with its workshop) for services and maintenance. Emulbitume Emulbitume has developed a new colloidal mill, the Atomix E, based on the same principle as its existing Atomix units April 2011 World Highways 31