The Nigerian Federal Ministry of Works and Housing awarded a contract for the rehabilitation of a 375 km section of the A2 highway from the capital city, Abuja, to the city of Kano in northern Nigeria with the cold recycling method to Julius Berger Nigeria Plc (JBN). Numerous Wirtgen Group plants and machines are already at work on the project.
The Abuja-Kaduna-Zaria-Kano Road (AKR) is a part of ‘Trans-African-Highways’, a network comprising transcontinental road construction projects in Africa. The aim of the project is the stimulation of the African economy through the construction of a well-developed network of road-based trade corridors. The redevelopment of the highway establishes better connections between the economically weaker north of the country and the stronger regions in the south.
The face of the project changed completely after the Nigerian government’s decision to redefine the objectives of the contract: Instead of ad hoc rehabilitation, the project now foresees the complete reconstruction of the roadway and hard shoulders and the provision of additional infrastructure such as footbridges, road lighting, toll roads, service stations and rest facilities along the highway. The reconstruction work is scheduled for completion in Q2/2023, and the deadline for the infrastructure measures has been set for early in 2024.
Wirtgen Group machine fleet
Two complete cold recycling and paving fleets with a total of 75 machines, including
Nigeria attaches great importance to the use of environmentally friendly technologies in infrastructure development programs. Cold recycling with foamed bitumen is a real innovation in the Nigerian road construction sector, and was proposed by Julius Berger as an alternative to conventional road construction measures from the start. As a highly-skilled and experienced partner, the Wirtgen Group not only supplies the necessary machines and equipment, but also accompanies the Nigerian company with a German heritage with technical support throughout the course of the project.
‘Cold recycling enables optimal use of existing construction materials and conserves valuable resources. This is why we are the first construction company in Nigeria to have committed ourselves to exploiting the full potential of this technology for our company and our clients.’
Benjamin Bott, Project Director, Julius Berger Nigeria Plc
Julius Berger had already imported two complete cold recycling and paving fleets with a total of 45 Wirtgen Group machines at the start of the project: Wirtgen large milling machines for the removal of the existing road pavement, Wirtgen soil stabilisers and cold recyclers and spreaders from Streumaster for preparing the road bed, Kleemann mobile impact crushers and Wirtgen cold recycling mixing plants for the production of mix from the milled asphalt, Vögele asphalt pavers and mobile feeders for asphalt paving and Hamm rollers for compaction.
JBN was so impressed by the efficiency and durability of the machines that an order has been placed for another 30 machines, including tractor-towed stabilisers and slipform pavers from Wirtgen and a number of Vögele and Hamm machines, for delivery this year.
In addition to the best machines and equipment for the job, the team from Julius Berger can also rely on the high levels of application expertise and technical advice and support the Wirtgen Group provides. On top of this, the reliable after sales service in Nigeria plays an essential role in assuring machine availability and the smooth running of this mega-project.
In addition to the cold recycling specialists from the Wirtgen Group, experts from the South African engineering firm Loudon Consultants were also involved in the project.
‘Our aim was to offer a technologically mature all-round package, so we decided to take advantage of the technical consulting services of the Wirtgen Group as well. On top of this, we had the outstanding after sales service here in Nigeria.’
Benjamin Bott, Project Director, Julius Berger Nigeria Plc (JBN)
Wirtgen WR 250 and WR 240 soil stabilisers are used to stabilise the road bed. For this purpose, SW 20 MC and SW 18 SC binding agent spreaders spread previously defined quantities of cement over the surface in advance. This treatment takes place at a depth of either 175 mm or 250 mm, depending on the nature of the soil.
Immediately afterwards, Hamm 3520 P soil compactors with padfoot drums begin the compaction process. After the required level has been achieved with a motor grader, Hamm 3520 D compactors with smooth drums produce an even, high-quality surface.
The asphalt milled off by Wirtgen large milling machines is transported to one of the mobile processing sites. There, a MOBIREX MR 110 Z EVO2 impact crusher reduces the grain size of the milled material from around 150 mm to the final grain size of 0/40 mm.
Immediately next to the crusher, a KMA 220 cold recycling mixing plant stands ready to produce the new BSM mix from the crushed milled material with the addition of 2% foamed bitumen and 1% cement.
The cold recycled material is distributed over the prepared surface as a 15 cm base layer and is then paved by Vögele SUPER 2100-3 Highway Class tracked pavers with HD configuration. Compaction is carried out by teams of HD 70 and HD 90 tandem rollers and GRW 15 and HP 180 pneumatic tyre rollers.
Even after the expansion of the project, the work on the A2 highway between Abuja and Kano is progressing with an outstandingly small carbon footprint – all thanks to the use of cold recycling with foamed bitumen.
Above all, the cold recycling method enables an up to 50% reduction in the quantities of binding agents required. This is particularly important, since binding agents still represent the largest cost factor in road construction and rehabilitation projects. Thanks to the special properties of BSM, cold recycling technology leads to extremely low costs throughout the service life of highways like the Abuja-Kaduna-Zaria Road in Nigeria.
