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Study of the fatigue and healing phenomena in MAF samples compounded with RAP

Grant number: 15/24082-1
Support type:Scholarships abroad - Research
Effective date (Start): May 01, 2016
Effective date (End): April 30, 2017
Field of knowledge:Engineering - Civil Engineering - Transportation Infrastructure
Principal Investigator:Adalberto Leandro Faxina
Grantee:Adalberto Leandro Faxina
Host: Amit Bhasin
Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
Local de pesquisa : University of Texas at Austin (UT), United States  

Abstract

Recycling of old asphaltic layers is a current practice in several developed countries and it has recently come up as an important issue in some Brazilian forums devoted to asphalt paving. Consolidated statistics describing the actual amount of old asphaltic layers available for recycling are still not available in Brazil but, on the other hand, the theme has been gaining wide repercussion to the extent that large volumes of milled material are accumulated. The old asphalt layer is still useful for several applications, since it contains mineral aggregate with quality similar to the virgin mineral aggregates and aged asphalt binder in contents slightly lower than the originally used. Such residue is noble and it cannot be simply discarded, taking into account not only the large volumes that are generated and the consequent environmental problems but also its large added value.Several studies performed over the last two decades, especially in the United States, have contributed decisively for the development of the recycling techniques that allow the use of up to 100% of recycled material to prepare new asphaltic layers. Out of these studies, the most relevant are those that determined that increasing contents of recycled material have a positive effect on the rutting resistance of the HMA mixes and a negative effect on the resistances to thermal and fatigue cracking. In order to try to minimize such detrimental effects of the addition of recycled material to new asphaltic layers, rejuvenators started to be used but, on the other hand, there are still some doubts about which are the most adequate rejuvenators and which are the ideal proportions that can be used.This research proposal is inserted in this context and aims to evaluate the effects of different rejuvenators in different proportions, using the modern technique of fatigue characterization of asphalt materials based on rheological tests with the fine aggregate matrix (FAM), including the effect of healing. A systematic study in this area can be useful to establish more thoughtful and scientifically supported processes to select materials addressed to recycling of aged asphaltic mixtures.