Cold in-place stabilization with foamed bitumen: rehabilitation works in the regional road ER361 between Amiais de Cima and Alcanena (Portugal)

Abstract

The present case study refers to the rehabilitation work in the Regional Road ER361 between Amiais de Cima and Alcanena, Portugal, using an in-place cold recycling solution with foamed bitumen. From a circular economy perspective, this solution allowed to make full use of the construction and demolition wastes (CDW) generally produced in this type of works. Two factors significantly impact the environment due to road rehabilitation works: • the need for raw materials, like natural stone, extracted with heavy machinery, negatively impacting the natural landscapes; • the other factor is the production in the asphalt plant, which heavily relies on fossil fuels. Among the benefits of the in-place cold recycling solution, the environmental gains achieved by reducing the use of natural aggregates and fossil fuel spent should be highlighted. Moreover, the reduction of heavy vehicle traffic for road construction also positively impacts noise pollution, Greenhouse Gas emissions and constraints to the expected level of road traffic. It should also be noted that shortly after applying the layer, it was possible to move through the site with a low level of ravelling or disintegration of the newly applied material. This solution has almost eradicated the need to extract natural minerals, has involved less heavy machinery, emitted fewer polluting gases into the atmosphere and can result in a solution with similar or even higher durability if the pavement structure is adequately designed. The advantages of cold in-place recycling with foamed bitumen are unequivocal, namely at environmental and execution levels, health & safety, deadlines reduction, and allowing immediate traffic use. The technical, economic and environmental advantages/disadvantages are evaluated in the present case study by implementing the cold in-place recycling with foamed bitumen solution versus a traditional pavement rehabilitation. The latter includes removing the existing pavement and applying new granular and hot mix asphalt layers. This study also focused on the importance of laboratory and on-site control for the new solution's success.