A cold recycling road rehabilitation train, which can mill, mix and pave old asphalt in a single pass, has been deployed on the Schoemanskloof stretch of the N4 road by construction contractor Tau Pele Construction, which is upgrading the stretch of road.

The train, sourced from construction equipment manufacturer Wirtgen, is now hard at work upgrading the 68 km Schoemanskloof stretch of the N4 highway, in Mpumalanga. The upgrade entails the construction of 50 km of additional lanes, in addition to the rehabilitation of the existing road and overlaying the entire project, says Tau Pele MD Frans Bouwer.

“With a mixing capacity of up to 800 t an hour, the W 380 CR cold recycler feeds recycled material into the VÖGELE SUPER 1900-5 X paver using its swivel-mounted and height-adjustable discharge conveyor at the rear. This makes it possible to complete long stretches of road in a single day of work,” says Wirtgen South Africa sales manager Waylon Kukard.

“The paver then paves the material back, to slope, to thickness and to the required width. The two 12 t Hamm tandem rollers are then deployed for optimal compaction of the material, before the two 24 t pneumatic rollers seal the layer,” he explains.

Capable of working widths up to 3.8 m, the W 380 CR cold recycler, which is the cornerstone of the train, granulates the material and transforms it into a homogeneous material mixture by adding a binding agent, which is foamed bitumen on this project, he adds.

The technology has been proven in other parts of the world, although it is new in South Africa. Cold recycling, particularly with foamed bitumen, is often used by road authorities and construction companies in Europe and South East Asia, says Wirtgen South Africa MD Heinrich Schulenburg.

The technology also saves time compared with conventional road rehabilitation equipment.

“This technology is a process plant in its own right. By combining milling, mixing and paving in one pass, the rehabilitation process is accelerated. The foamed bitumen is processed in-place with the existing material, enhancing strength by increasing cohesion and durability,” says Schulenburg.

The newly laid bitumen-stabilised material provides a solid base, thereby making the road immediately available to traffic after compaction and reducing traffic disruption.

These considerations drove the decision to deploy this technology on the Schoemanskloof project, as the N4 generally experiences high traffic volumes, with more than 2 000 heavy vehicles a day.

The highway serves as a vital artery connecting South Africa’s industrial heartland, namely Gauteng, to the deep-water Port of Maputo, in Mozambique, and enables efficient, cost-effective transport of goods, including agricultural produce and minerals.

“The N4 is one of the most important trade routes in the region, making reduced interruption of traffic of the utmost importance. The stop-and-go traffic control system associated with conventional road rehabilitation techniques generally halves the normal capacity of the road for long periods, which causes severe backups and bottlenecks,” says N4 concessionaire Trans African Concessions (TRAC) Engineering and Technical executive manager Wimpie Janse van Rensburg.

By milling, mixing and paving in one pass, the cold in-place recycling system allows the road to be reopened almost immediately, which reduces traffic congestion and delays, he adds.

Additionally, the cost efficiency of this technology was another major driver in the purchasing decision. The Wirtgen cold, in-place recycling train saves on project costs by reducing the need for new materials, reducing transport costs and allowing for faster, more efficient construction, says Tau Pele director Joe Deetlefs.

Depending on the project, savings in material costs can be anything up to 50%. In addition, reuse of 100% of existing asphalt eliminates landfill waste and reduces the need for new raw materials by up to 90%, thus maximising environmental sustainability, says Kukard.

By eliminating up to 90% of truck transport for material removal and delivery, the system allows for a significant reduction in CO₂ emissions associated with the construction project, he says.

Reuse of existing materials is becoming more important in road rehabilitation. As natural materials become scarcer globally, using reclaimed asphalt pavement on site allows for faster, cheaper and greener road repairs, says consulting engineering firm KBK Engineers contract engineer Jaco Markam.

“All project stakeholders in the construction value chain must work together to use what we have. Reusing in-place materials eliminates the need to purchase virgin materials and pay for transporting them to the site, and this technology is already available,” he says.

The deployment of the new machine was the culmination of a partnership between Tau Pele, which is the main contractor on the Schoemanskloof road upgrade, TRAC and KBK Engineers to usher in a new era in road rehabilitation in South Africa.

The three partner organisations first saw the technology at construction machinery trade fair Bauma 2025 in Germany, and recognised its value proposition, which prompted discussions with Wirtgen South Africa to bring the technology to South Africa.

“The construction industry must move fast to adopt new technologies to overcome chronic productivity, safety and efficiency challenges, with the aim of reducing project delays, material waste and cost overruns,” says Janse van Rensburg.

TRAC manages the 580 km N4 Toll Route from the Solomon Mahlangu offramp in Tshwane, Gauteng, to the Maputo Harbour, in Mozambique.