Many steps pave the way.

Asphalt paving requires an exceptionally high degree of meticulous logistical planning and management. Care needs to be taken that sufficient quantities of mix are available on site all the time, and that the mix will not cool down prematurely. What types of machines are used for asphalt paving? What is the sequence of operations?

There is one machine team which has made itself indispensable to asphalt paving for many decades: road paver and road roller. Very simply put, asphalt is placed by the paver and compacted by the roller.

Conveying in longitudinal direction

The asphalt paving gang is always “headed” by the truck driver. He reverses his truck up to the paver to dump the asphalt material into the paver’s receiving hopper. Two independently operating, slightly inclined scraper conveyors then transport the material to the rear part of the machine. Using slightly inclined conveyors permits increased discharge heights, while additionally enabling increased paving thicknesses without pressing the mix into the auger chamber.

Reversing the direction of movement

The belt speed is controlled in proportion to the filling level at the end of the scraper conveyor. To prevent the loss of paving mix when repositioning the machine, the material can be drawn back by briefly reversing the belt’s direction of movement.

Conveying in transverse direction

Two independently controlled, rotating feeding augers located between the paver and paving screed spread the material evenly in front of the screed. The augers can be extended so as to fully adapt the conveying width to the machine’s paving width.

Sensor control of feeding auger

The auger’s speed of rotation is controlled by sensors in proportion to the head of mix in front of the screed. This feature enables the mix quantity to be fully adapted to requirements when paving in bends or at varying paving thicknesses. The auger’s direction of rotation can be reversed if necessary, transporting the mix from the periphery towards the centre.

Supply of mix and job site logistics

The hot mix should be covered when delivered 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 paver’s laydown capacity.

Continuous supply of material

If the paver stops moving 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.

Pre-heating the paving units

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. Last but not least, the screed needs to be adjusted to the correct paving width.

Using the screed for pre-compaction

Modern road pavers allow the compaction systems of the paving screed to be controlled in accordance with specific requirements. High-density screeds, in particular, are capable of achieving excellent density values.

Optimum final compaction

Compaction effected by the high-density screed enables the rollers which follow behind the paver to achieve the overall final density specified by the client in fewer roller passes. In most cases, the road paver is geared for either high density or fast advance speed, both of which have an effect on the number of roller passes required.