Capital Equipment News January 2016

COVER STORY

density specified by the client in fewer roll- er passes. In most cases, the road paver is geared for either high density or fast ad- vanced speed, both of which have an effect on the number of roller passes required. GETTING THE ROLLERS READY Rollers are heavy road construction machines used for compacting hot and therefore flexible asphalt pavements. To prevent them from causing damage to the new asphalt surface, they must not come to a stop during the compacting operation. For precisely that reason, machine maintenance is of particular importance. In addition to that, checks need to be carried out prior to commencing work to make sure that the drum is clean, that fuel and engine oil are available in sufficient quantities, and that the water tank has sufficient water for the drum spray system. Basically, compaction becomes more ef- fective with increasing temperature of the paved mix. The most advantageous temperature range depends on the com- position of the mix, the thickness of the pavement and the type of binder used. The roller operator starts compaction at the

individual options for every individual cus- tomer – from single machines to integrated solutions for the entire process cycle. THE GLOBAL NUMBER ONE When it comes to roads, the Wirtgen Group offers impressive, innovative solutions, internationally recognized processes and a mature, seamless range of products that satisfies the most exacting demands. Be it for earthwork and rock construction, new road construction or road rehabilitation, asphalt or concrete roads, narrow cycle tracks or airport runways around the world – the Wirtgen Group offers its customers an impressive range of products and services. MANY STEPS PAVE THE WAY The first person in the paving team, however, is the truck driver who fills the asphalt into the paver’s hopper. Two mutually independent conveyors transport the material through the machine to the rear, where it is uniformly distributed between paver and screed by two individually controlled rotating screw conveyors. When paving a standard mix, the temperature should always remain above 110 °C in order to ensure sufficient time for compaction.

The hot mix should be covered when deliv- ered by charging trucks to ensure that the paving operation is carried out in the most suitable time frame. To guarantee continuous paving, the capacity of the asphalt mixing plant always needs to be higher than the pav- er’s laydown capacity. If the paver stops mov- ing due to lack of material, disruptive lateral joints occur as a result of the paved layer cooling down. When paving standard mix, the paving temperature should be higher than 110°C to allow an as large time frame as possible for compaction. PAVING WITH THE ROAD PAVER All paving units need to be heated prior to commencing the paving operation to prevent the mix from sticking to sensitive parts of the machine. On modern pavers, the compacting systems in the screed can be actuated separately. Particularly the high compaction screeds achieve very good compaction. As a result, the rollers behind the paver require fewer passes to achieve the specified final degree of compaction. Compaction effected by the high-density screed enables the rollers which follow be- hind the paver to achieve the overall final

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CAPITAL EQUIPMENT NEWS JANUARY 2016