Sustainable paving in super-quick time

A southern section of the Berlin orbital road needed renewing as a result of severe rut formation. In order to rehabilitate this busy section of highway to a high standard as quickly as possible while conserving resources, the contractor used two InLine Pave trains from Vögele. They paved the surface and binder courses "hot on hot" and "hot to hot”, not only increasing the road surface’s quality and resistance to deformation but also saving time, money, and resources.

Two layers in one pass

Consequently, the contractor – a consortium comprising Matthäi Michendorf and Matthäi Stendal – decided to pave “hot on hot”, deploying two Vögele InLine Pave trains. This method involves the material feeder, the binder course paver and the surface course paver working in line, to lay down both the surface and binder courses in one pass. This delivers a number of benefits: “Hot on hot” paving of the binder and surface courses guarantees optimum bonding between the two, improving the quality and service life of the surface course. The proportion of surface course relative to binder course can also be reduced. That improves the stability of the pavement thanks to the higher proportion of stable binder course, and prevents deformation. The method also saves money, because less binder-rich surface course material – much more expensive than binder course material – is required. Unlike in the conventional paving method, there is also no need to spray on bitumen emulsion, which saves on material, and cuts CO₂ emissions and working time. “The InLine Pave method is ideal for highway projects in particular, as well as generally for projects requiring a highly resilient pavement to be laid under significant time and cost constraints, and taking account of sustainability aspects,” says Matthäi paving supervisor Frank Jilge.

Two pave trains for maximum efficiency

The time window for rehabilitating this section of highway was extremely tight. The entire section had to be renewed and then reopened to traffic in just two days. So the paving team used two InLine Pave trains, each comprising three machines: MT 3000-3i Offset high-performance material feeders received the material for the binder and surface courses, and conveyed it in a set timing sequence straight to the material hopper or to the transfer module of the following SUPER 2100-3i IP. The modified Highway Class pavers created a 6 cm (2.36 in.) thick binder course, and conveyed the surface course material via the transfer module to the following SUPER 1900-3i, which then directly laid down the 2 cm (0.8 in.) thick surface course. In order to meet the tight time constraints, the two pave trains worked in parallel on two lanes, each 7.5 m (24.6 ft.) wide. “The combination of 'hot on hot’ and ‘hot to hot’ really helped us get the maximum efficiency out of the machines,” says Jilge.

High compaction guarantees quality and durability

The InLine Pave method was also a good choice in terms of quality requirements. Both the thinner surface course and the high degree of precompaction contributed to the high quality and stability of the new roadway. The core of the pave train, the SUPER 2100-3i IP paver for the binder course, was equipped with an AB 600 TP2 Plus extending screed. With a tamper bar and two pulsed-flow hydraulic pressure bars, the extending screed achieves maximum compaction values of up to 98%. This allowed the paving team to compact the binder course so that it was highly resistant to deformation, allowing the surface course pavers which followed to work on the layer beneath immediately, while it was still hot. The high degree of precompaction meant that only a few passes of the roller were subsequently required, again saving working time.

Focus on sustainability

The aims of both the client and the contractor in rehabilitating the Berlin orbital road were to utilize machines and material as efficiently as possible, and to conserve resources. The InLine Pave method impressed in this regard too. “Hot on hot” paving meant that there was no need for the bitumen emulsion tack coat used in conventional paving, saving on material, cost, and the CO₂ emissions generated during production and paving – as well as additional working time. A further factor was that Matthäi also uses all the machines in the IP train as standard, so is able to utilize them to the full. The only adaptation for conventional paving when required is to remove the binder course paver’s transfer module.

Tried and tested method

The project on the Berlin orbital road was a success: Matthäi completed the job on schedule, in two days. “While every job site presents fresh challenges, at least the paving method was a tried and tested one for us,” says Jilge. “We have been deploying InLine Pave technology from Vögele since 2004, because it delivers so many benefits. Large-scale and highway job sites are routine for us, so reliable machine technology and on-site application consulting are key to our success.”