Reciclagem de misturas asfalticas : Evoluçao apos 20 anos e a situaçao atual na França
Résumé
Over the past decade, environmental concerns have led to the search of technical solutions that meet sustainable development criteria. In France, this was resulted in recommendations from Grenelle 21 and in a voluntary commitment convention among construction companies, in 2009, for reducing the environmental impact of roadworks (reuse of all waste from the process, reduce greenhouse gases, saving non-renewable materials, eco-calculator, ...). To meet these expectations, high modulus asphalt mixtures (EME) have been, for over than 20 years, a high performance solution to address aspects related to saving materials and significant increase in service life of the pavement structure. On the other hand, hot mix asphalt recycling using high percentages of reclaimed asphalt pavement (> 50%) has demonstrated effectiveness in improving the ‘environmental performance’. This paper presents an overview about the evolution over 20 to 30 years of hot mix recycling in plant, making an assessment of the current situation in France and comparing it with the worlwide situation (discussed in PIARC 2010), and addressing the use of reclaimed asphalt pavement in the major European countries, as well as United States, Canada and Japan. This work presents the most important characteristics when combining these two subjects, i.e., an EME containing 50 and 65% of reclaimed asphalt pavement. The main topics discussed include homogenity on the recycled material's source (asphalt wearing course), preliminar studies in laboratory, new mixing plants containing two separate mixers (one is specific for heating the reclaimed material and for quality control). The main idea of this paper is verifying the performance of the asphalt mix, for comparisons concerning the preliminary studies and the laboratory tests with asphalt mixes from the plant, in order to assess the mechanical properties, such as complex modulus, fatigue resistance and rutting. For complementing this study, analyses of the asphalt properties were carried out, especially about the interactions between the new and the old bitumen in the recycled mixes. Rejuvenator agent was not employed, but a hard asphalt. Conventional properties of the bitumen are also presented, as well as rheological properties and physical composition of the asphalt. Finally, this work shows an operational protocol developed for producing the recycled mixes in laboratory. This study provides an important technological advance, contributing for a better knowledge of recycled mixes containing high percentages of reclaimed asphalt pavement.
Domaines
Matériaux
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