Using technology from Wirtgen, JBN has been able to carry out the environmentally friendly reconstruction of a 375km road stretch using the cold recycling method.
The Nigerian Federal Ministry of Works and Housing extended the scope of the contract agreed with JBN from rehabilitation to the reconstruction of the A2 dual carriageway. The route connects the capital city Abuja in central Nigeria with Kano, in the north of the country. Instead of the rehabilitation methods used previously, the project is now seeing the complete reconstruction of all lanes and the hard shoulders.
The project is of enormous economic relevance for Nigeria and West Africa as a whole. The reconstruction of 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 is the stimulation of the African economy through the construction of a well-developed network of road-based trade corridors. The programme will help to establish better connections between the economically weaker regions of the north and the economically stronger southern regions.
From the beginning, the environmentally friendly cold recycling method was considered as an alternative to conventional road construction methods. The proposed use of this method was one of the factors that led to JBN winning the contract. The completion of the reconstruction project is scheduled for Q2/2023, and the completion deadline for special structures has been set for early May 2024. Despite the tight schedule, JBN is optimistic that the project can be realised as planned, due to the time saved by the cold in-plant recycling method. Depending on the application, the cold recycling process involves mixing foamed bitumen into the existing construction materials in-place with an in situ cold recycler, or in-plant, with a mobile cold recycling mixing plant located close to the construction site. In the case of this project with a travelling construction site, the contractor decided that the in-plant method would be the best option. The newly produced bituminous mix is known as bitumen-stabilised material
(BSM). After paving and subsequent compaction, BSM offers long-term durability and high load bearing properties. From a long-term perspective, BSM has other advantages also. The foamed bitumen which is mixed in leads to selective adhesion within the cold recycling layer and prevents cracking. As part of the pavement structure, the permanent layers prepared in this way form a strong base for asphalt surfacing with reduced layer thicknesses or fewer layers.
JBN has adopted this construction method as the best long-term solution and sees it as a real innovation in the Nigerian road construction sector: "Cold recycling enables optimal use of existing construction materials and conserves valuable resources. This is why we are the first construction company in Nigeria committed to exploiting the full potential of this technology for our company and our clients," explained project director Benjamin Bott.
Two complete cold recycling and paving fleets comprising 45 machines were ordered at the start of the project. These included large milling machines and soil stabilisers from Wirtgen, cold recyclers and spreaders from Streumaster, Kleemann mobile impact crushers and Wirtgen cold mixing plants, Vögele asphalt pavers and mobile feeders and rollers from Hamm. In addition, 30 more machines were shipped to Nigeria in the course of the fleet expansion due to the success of the first units and the strength of the customer support according to JBN. The work has continued with a low carbon footprint, even after the expansion of the project. As there is no need to dry or heat the base materials, fuel consumption can be reduced by 10-12litres/tonne in comparison with conventional rehabilitation techniques. The recycling of the surface layer also reduces construction material transportation needs by up to 90%. At the same time, 90% of the costs for resources and 100% of material disposal costs can be saved.
This delivers a significant reduction in fuel consumption and lower CO2 emissions. Above all, the cold recycling method also allows savings of up to 50% of the binding agents required, a major cost saving in road rehabilitation projects. And the good properties of BSM will allow cold recycling technology to deliver low costs throughout the service life of the important Abuja-Kaduna-Zaria Road.