Ayrton Senna Highway rehabilitated with Cold Recycling
Date: 03 July 2015
SAO PAULO/BRAZIL, July 2, 2015 - The SP-070, also known as the Ayrton Senna Highway, is another motorway in Brazil where the time-saving, cost-efficient and eco-friendly benefits of the cold recycling process have been put to the test.
The SP-070 is an important transport link between São Paulo and Campos do Jordão, Vale do Paraíba and Rio de Janeiro, as well as being the main access route to Guarulhos International Airport. Since 2009 it has been operated by Ecopistas, which has a 30-year concession for the maintenance of the Ayrton Senna Highway.
Structural repairs have been carried out on a 35-km section – the stretch between the 11 and 46 kilometre marks – which extends from São Paulo in an easterly direction. And not before time, since the 25-cm cement-bound base course that lies under the asphalt was severely damaged due to the high daily volumes of some 125,000 vehicles in each direction, of which 15% comprise heavy goods vehicles.
Optimum solution: Cold recycling in-situ
Both Ecopistas and Fremix Engenharia e Comércio Ltda., the company contracted to rehabilitate the road surface, decided to use the technology that would deliver the best results in the fastest construction time: recycled material with foamed bitumen, produced in Wirtgen's mobile cold recycling mixing plant KMA 220.
When selecting the optimum rehabilitation method, the contractors also needed to meet one strict condition: on working days, the construction work on this vital transport route was restricted to an overnight 8-hour window from 9 p.m. to 5 a.m., since even the most minor closures for roadworks can cause massive traffic hold-ups. The tight timeframe meant that a thick asphalt pavement was out of the question. While the thicker asphalt layers produced in conventional rehabilitation processes need to cool for about four days – and for concrete pavements, setting takes even longer – Wirtgen's cold recycling technology allowed the pavement to be repaired section by section before being immediately reopened to traffic.
"During the daytime, no lanes can be closed between the São Paulo city limits and the airport, due to the high volume of traffic. That's why the work was carried out at night during the week or at weekends," explains Elio Cepollina Junior, Commercial Manager at Fremix.
With a maximum milling depth of 320 mm, the Wirtgen cold milling machine W 1900 can remove entire pavements comprising the surface, binder and base in a single pass, saving time and ensuring high productivity. | photo: Wirtgen Group
Wirtgen cold milling machines and Kleemann jaw crushers clear the way
The approximately 10-cm asphalt surface course and the underlying 25-cm cement stabilization layer, both requiring rehabilitation, were milled out separately and conveyed onto trucks. For this task Fremix used two of Wirtgen's large milling machines, the W 1900 and the W 200.
The reclaimed material was transported by truck to a mixing location set up in close proximity to the site. Here it was crushed using a state-of-the-art Kleemann MC 110 Z EVO track-mounted jaw crusher to ensure that the grain size did not exceed 20 mm and that the material had an optimal granulometric composition. The mobile crusher can be used for a variety of applications, including the preparation of both natural stone and asphalt and materials that have been quarried or mined.
The Kleemann MC 110 Z EVO jaw breaker crushes reclaimed material to a maximum grain size of 20 mm before it is recycled in the KMA 220. | photo: Wirtgen Group
Wirtgen KMA 220 recycles reclaimed material on site
Using two Wirtgen mobile cold recycling mixing plants KMA 220, the reclaimed material was then recycled into a top quality mix with foamed bitumen (BSM). The KMA 220 is easy to transport and can be quickly set up on site. As a result, the two plants were quickly installed next to the motorway, greatly reducing the number of material transfers.
Precision metering of binders
Loudon International and its engineers were in charge of the mix design and quality monitoring. Working with the technicians from JBA Engineering and Consulting Ltda., they provided support for the preliminary investigations and project execution. Using the results of preliminary tests carried out with the Wirtgen laboratory scale foamed bitumen plant WLB 10 S, the quality of the foamed bitumen and the optimum composition of the mix – obtained in combination with the Wirtgen laboratory-scale twin-shaft compulsory mixer WLM 30 – could be precisely identified before construction work commenced. The formula finally selected comprised 1% hydrated lime and 2% bitumen.
The SUPER 1300-3i road paver by Vögele is extremely compact and yet has a high laydown rate and pave width of up to 5 m. | photo: Wirtgen Group
The hot bitumen is foamed in the expansion chamber of the KMA 220 by adding air and water. This produces foamed bitumen which is 20 times the volume of the original product. The foamed bitumen is combined with the hydrated lime and the reclaimed material to produce a homogeneous mix. The recycled reclaimed material was paved in two layers: The 20 cm-thick first layer was compacted by both a 14-t Hamm 3414 compactor and a 9-t Hamm HD 90 tandem roller, and then the HD 90 completed the compaction of the 13 cm-thick second layer on its own. The Vögele SUPER 1300-3 tracked paver was used to apply an unusually thin 2-cm surface course. A Hamm GRW 280 rubber wheeled roller took care of the final compaction of the asphalt mix.