Life Cycle Assessment of low temperature asphalt mixtures for road pavement surfaces: a comparative analysis. Resources, Conservation and Recycling, Elsevier, 2018, pp.

Road accidents increase during the first rain after a long dry period. It is widely accepted that the tire traction loss is due to fine particles accumulated on the road surface. Yet, the involved mechanisms at the tire/road interface are not clearly understood. This paper deals with the particle-induced lubrication on dry road. Tests are performed in laboratory. Sediments are extracted from a catchment area which collects runoff water. The process of extracting particles from sediments in laboratory by drying and sieving is described. Particles are separated into fractions characterized by their chemical composition and size distribution. Protocol to simulate the process of particles' build-up on the road surface is described. The effect of the particle's size and concentration is studied. Surfaces representative of real road surface textures are tested. Friction tests are conducted using the Skid Resistance Tester, which is widely used to assess friction characteristics of road surfaces. Samples are weighed before and after each friction run. On a surface initially covered by a compacted particle layer, successive friction runs are performed, without resupplying particles, to follow the evolution of the friction coefficient with the particle depletion. Friction drops significantly when a surface is covered by particles. Successive runs induce an increase of the friction coefficient until reaching a stable value which is still lower than that of a clean surface. Particles are considered as third bodies introduced artificially in the interface between the friction slider and the test sample. Analysis of particles' flows (particles trapped and ejected), through particles' mass extracted from weighing, helps to explain the friction variation. Assuming that friction is governed by the surface fraction (X) covered by particles, a model was developed. The calculated friction coefficient is a weighted sum of friction coefficients when the surface is respectively clean (X = 0) and fully covered by particles (X = 1). It was found that the surface fraction can be expressed as a function of the ratio of available particles' mass to initial particles' mass. Comparisons between model and experiment are satisfactory. Discussions are made in terms of interactions between surface textures and particles' size and concentration.

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Tire–road interaction addresses safety with respect to braking friction and energy efficiency in the context of rolling resistance. These phenomena are coherent, but their engineering solutions can be contradictory. For example, highly skid-resistant surfaces may not be ideal for fuel economy, but surfaces with low rolling resistance may be prone to skidding. Several experimental and numerical studies have investigated the individual phenomena, but insufficient attention has been paid to studying them coherently. The present study computed braking friction and rolling resistance for various operating parameters and their coherent response for each parameter with the use of a thermomechanical contact algorithm. Micromechanical finite element simulations of a rolling or braking pneumatic tire against selected asphalt concrete surfaces were performed for various operating conditions, such as tire load, inflation pressure, speed, and ambient air and pavement temperatures. The coefficients of braking friction and rolling resistance were found to decrease with the inflation pressure and the temperature and to increase with the wheel load. The braking friction coefficient was found to decrease with the speed, in contrast to the rolling resistance coefficient, which increases with the same parameter. A full-skidding tire registered lower braking friction than a 20% slipping tire. Also, an asphalt surface with higher macrotexture offered higher braking friction and higher rolling resistance, and vice versa.

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As pavement community members head into the future, the increasing social pressure towards the incorporation of sustainable principles into their work urge them (1) to come up with new materials and practices that reduce the negative impacts of their activities in the surroundings and (2) to develop methodologies and tools to encourage sustainable decision-making. To this end, this paper presents the development of a life cycle, performance-based, sustainability decision support system (DSS) for helping decision-makers (DMs)/stakeholders to prioritize alternative technologies for transportation systems with the ultimate objective of fostering sustainability in transportation projects. The framework relies on a multi-criteria decision analysis (MCDA) method to rank the sustainability of alternatives based on their life cycle sustainability performances and the relative priorities with respect to each environmental, economic and social criterion. The applicability of the proposed DSS is illustrated by means of a case study that aims to identify the most sustainable asphalt mixture amongst several promising options ranging from low to hot temperature asphalt for wearing courses of flexible road pavements. The sustainability assessment applies life cycle-based approaches to quantify the values of a set of indicators purposely and methodologically selected to capture the cause-effect link between the general concepts of the three Wellbeing dimensions of sustainability, i.e., environmental, economic and social, and the infrastructure construction and maintenance practice. The results show that a foamed WMA mixture with a RAP content of 50% is the most sustainable among the competing alternatives. Furthermore, a sensitivity analysis conducted to investigate the influence of indicators weights and parameters of the MCDA method on the stability of the ranking showed that its first position in the ranking remained unaffected.