• Projet National MURE
Programme de recherche MURE – MUlti-Recyclage des Enrobés tièdes

Articles scientifiques

Towards a better understanding of wetting regimes at the interface asphalt/aggregate during warm-mix process of asphalt mixtures

S. Vassaux, V. Gaudefroy, L. Boulangé, A. Pévère, V. Mouillet, V. Barragan-Montero

Construction and Building Materials, Volume 133, 15 February 2017, Pages 182-195

DOI : https://doi.org/10.1016/j.conbuildmat.2016.12.015

In road applications, the current challenge is to develop more ecological products while maintaining asphalt mixture performance and durability. This sustainable development politics in civil engineering leads to promote techniques saving both energy and raw materials like combining the use of warm mix asphalt concretes (WMA) with the use of reclaimed asphalt pavement (RA). However, one of the current problematic when combining WMA and RA is to assess the quality adhesion of the “asphalt/aggregate” couple that is a fundamental parameter for the good mixture properties at short time and thereby durability of this composite structure. Indeed, the reduction of the manufacture temperature and the use of an aged binder may also have consequences on adhesion quality between asphalt and aggregates. It is the reason why it is crucial to identify the most impacting factors of wetting phenomena at the interface “asphalt/aggregate”. So, in this paper, the role of asphalt characteristics (viscosity, ageing, composition) as well as the one of substrate was investigated.

The substrate heterogeneity degree determines asphalt wetting behavior. For a model glass substrate, only asphalt characteristics have an impact: asphalt viscosity, polarity and saturates content are influent factors. On the mineral heterogeneous substrate, asphalt viscosity and asphaltenes content have an impact on wetting indicators. Substrate heterogeneities also appear as a very important factor which improves considerably wetting quality. The tested mineral substrate has been revealed as a biphasic composite material for which the wetting regime was modeled by a Cassie-Baxter model. A comprehensive approach has been proposed to explain asphalt wetting on heterogeneous substrates in correlation with Scanning Electron Microscopy observations. This Cassie-Baxter model is essential to understand adhesion phenomena on heterogeneous road materials. It seems also to be a promising way to evaluate quality adhesion of “asphalt/RA” mixtures.

Construction and Building Materials

Bitumen extraction and recovery in road industry: A global methodology in solvent substitution from a comprehensive review

L. Ziyani, L. Boulangé, A. Nicolaï, V. Mouillet

Journal of Cleaner Production, Volume 161, 10 September 2017, Pages 53-68

DOI : https://doi.org/10.1016/j.jclepro.2017.05.022

In the roadworks sector, extraction is a crucial step that consists of separating the bituminous binder from the mineral matter in asphalt mixture or reclaimed asphalt using a chlorinated solvent before the characterisation of binders’ properties and content. This review, conducted on scientific articles, technical papers and standards from 1996 to 2016, combined all existing bitumen extraction/recovery methods to toxicological data and health concerns as well as inputs on circular economy and sustainability of solvents. Nearly 50% of the documents dated from 2001 and found in this study deal with these latest aspects. There are ten different methods for extracting and two methods for recovering bituminous binders using eight of the most common solvents. One crucial point highlighted by the literature is that the nature of solvent has a significant impact on the final properties of the recovered binder. The quality of extraction and binder recovery operations largely depends on the solubility of the binder in relation to the solvent. According to the calculated Hansen solubility parameters, the lowest relative energy difference parameters (solubility study) are obtained using perchloroethylene, 1,1,1-trichloroethane and xylene solvents. This means that these solvents are the most compatible with bitumen. There is a relationship between the relative energy difference and the octanol/water partition coefficient currently used in the environmental risk assessment. All the Strengths, Weaknesses, Opportunities, Threats of different extraction and recovery methods currently in use highlights the fact that at this time, there are no alternative products that are as effective under the current technical conditions of use as chlorinated solvents. This represents a challenge for new research in the trade industry and in health institution to find a substitute for chlorinated products that meets all the sustainability and circular economy criteria.

Journal of Cleaner Production

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Président : Philippe REDOULEZ (ATMB)
Directeur : Jean-Eric POIRIER (USIRF/COLAS)
Directeur adjoint : Christine LEROY (USIRF)
Coordinateur IMPROVMURE : Simon POUGET (USIRF/EIFFAGE Infrastructures)

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