Proceedings of the 5th International Symposium on Asphalt Pavements & Environment (APE)

Inhaltsverzeichnis

1. Frontmatter

2. Sustainable Pavements and Environmentally Friendly Technologies

   1. Frontmatter

   2. Effectiveness of Rejuvenators for Asphalt Mixtures with High Reclaimed Asphalt Pavement Content in Cold Climates

      Marco Pasetto, Giovanni Giacomello, Emiliano Pasquini

      Abstract

      Current needs require the use of low environmental impact technologies in construction works. At the same time, the natural deterioration of roads makes maintenance and rehabilitation operations inevitable, with the consequent production and storage (or disposal) of huge quantities of Reclaimed Asphalt Pavement (RAP). Extensive research has thus been conducted and is still ongoing to maximize RAP recycling, trying to minimize the issues related to production and in-service properties, in particular in cold climates. This paper evaluates the feasibility of using large amounts of RAP in asphalt mixtures subjected to cold temperatures. With this aim, mixes were analyzed with different RAP contents (50% and 70%) and prepared with or without the addition of rejuvenator (two types of rejuvenators were selected). A traditional control mixture was also produced for comparison purposes. Dry and wet indirect tensile strength as well as stiffness and resistance to repeated loading properties at low and mid-service temperatures were assessed. Overall, the results showed a similar efficacy of the two rejuvenators in guaranteeing satisfactory mixture performance at low temperatures.

   3. Micromechanical Surface Investigation of Bio-modified RAP Binder

      Maria Chiara Cavalli, Lily D. Poulikakos

      Abstract

      Pavements are constantly subjected to oxidation and aging during their performance life, causing an increase in stiffness and brittleness and their lower ability to withstand stresses. This is even more pernicious when using reclaimed asphalt pavement (RAP) which cannot be used as it is and needs to be modified with rejuvenators. Up to now, the rejuvenating effect has been evaluated in terms of the improvement of rheological properties whereas the rejuvenation mechanism at micro-scale remains unclear. In this work, RAP with three different bio-based rejuvenators (a natural seed oil, a cashew-nut shell-based oil and a tall based oil) have been analysed by using dynamic shear rheometer (DSR) in combination with atomic force microscopy (AFM). Rheological tests showed how rejuvenators may restore the mechanical properties of RAP binder. On top of, AFM has been used to measure the mechanical properties at the sample’s surface such as the Young’s modulus. Consequently, quantitative nano-mechanical surface maps have been created and the effect of rejuvenators in restoring the elastic moduli at the RAP’s surface has been demonstrated. Furthermore, samples were analyzed after standard aging procedures (RTFOT and PAV) and rejuvenators’ effect have been studied. The addition of rejuvenators decreased the elastic moduli of the RAP binder at the sample’s surface and the bulk by decreasing the complex moduli. However, aging had a consequence on all binders’ surface and this effect was rejuvenators’ dependent.

   4. New Fluxing Agent for the Road Industry – An Overview of Technical Performances and HSE Benefits

      Thomas Lebarbé, Frédéric Delfosse, Hélène Martin, Arnaud Bourdette

      Abstract

      Fluxing agents (or flux oils) are oil products added to bitumen in order to decrease the viscosity of the binder hence allowing spraying, coating and paving applications more efficiently. Following the application on the road substrate, the flux oil evaporates to recover original binder’s properties.

      In 2015, Solvay and Eurovia have associated their own expertise in chemicals and road construction respectively, to design a new versatile fluxing agent for the road industry. This new flux oil has an outstanding safety profile (no labelling, and high flash point). It is partly bio-sourced (45% of its carbons are bio-sourced), the other part being a side-product of Solvay’s plant production, and fully biodegradable. Because of its unique properties this new flux oil needs less concentration (−20 to 45%) than other fluxing agents to decrease the viscosity of bitumen hence minimizing the use of volatile compounds. Moreover, it enables a quicker cohesion build-up of fluxed bituminous products.

      The fluxed binders are devoted to various types of application including surface dressing, micro-surfacing, cold mixes and storable mixes used in maintenance.

      This paper aims to describe the numerous technical and other advantages of this new product based on laboratory and jobsite results.

   5. Towards a Better Assessment of Recycling Agents Effects on Bitumen During Hot Recycling

      Fayçal Lahjiri, Sabine Gazeau, Frédéric Delfosse, Anne Dony, Layella Ziyani, Virginie Mouillet, François Henn

      Abstract

      The current challenge is to produce asphalt mixtures incorporating higher rates (>50%) of Reclaimed Asphalt (RA) while controlling the quality of the final mix. During the service life of a pavement properties change, mainly due to oxidation and need to be restored. The resulting mix must exhibit at least equivalent performances regarding the mechanical and durability properties compared to that from a mix without RA. Hence, recycling agents are sometimes employed to “rejuvenate” aged bitumen. In this study, three recycling agents were used on both RA and neat bitumens, displaying different compositions. The effects on unaged and aged blends were assessed through rheology tests using Dynamic Shear (DSR) and Bending Beam (BBR) Rheometers. Data from DSR obtained with 4 mm and 8 mm parallel plates allowed to calculate the Glover-Rowe criteria and to determine the crossover parameters whilst BBR measurements yield Tm, Ts and ΔTc parameters. The blends resulting from the two bitumens displayed a similar evolution of behavior. This outcome suggests that these tests cannot discriminate the origin of the rejuvenation phenomenon since they only highlight the softening effect of the recycling agent and not its impact at the molecular level, i.e. on asphaltene and maltene compounds.

   6. Graphene-Enhanced Recycled Asphalt Pavements

      Loretta Venturini, Fabrizio Monti

      Abstract

      100% Italian innovation: a new graphene-enhanced super-modifier (GESM) developed by Iterchimica Srl. In November 2017, the three-year-long research ended with a patent filing. This is the evolution of the traditional Polymer Modified Asphalt (PMA - dry method) technology and it consists of polymeric compound additivated with graphene. An experimental research was carried out with virgin aggregates and it showed greater fatigue resistance (up to +250%), higher resilience and lower thermal susceptibility, throughout a wide range of test temperatures. In September 2018 the first on-site trial section was carried out near Rome. The project consisted in the laying of binder (7 cm) and wearing courses (3 cm) with respectively 40% and 30% of Reclaimed Asphalt Pavement (RAP), and an adequate rejuvenator. A kilometer of road was divided in four segments, each made with a different technology: traditional non-modified asphalt concrete, “soft” PMA with standard polymeric compound, “hard” PMA with SBS (Styrene-Butadiene-Styrene) and PMA with the innovative GESM. During the production/laying phases and the following months, the trial pavement was constantly monitored in collaboration with University La Sapienza of Rome. It will be also monitored for the following 5 years. The paper shows the first comparison results between segments 1 and 4.

   7. Properties of Asphalt Binders with Increasing SBS Polymer Modification

      Mike Aurilio, Peter Mikhailenko, Hassan Baaj, Lily D. Poulikakos

      Abstract

      The properties of several asphalt binders with gradual styrene-butane-styrene (SBS) polymer modification were studied. The base binders used were straight-run PG 52-34, 58-28 and 64-28 which were modified with polymers at concentrations of 0, 1, 2, 3 and 4%. Two types of SBS polymers were used with different grain sizes and they were integrated into the binder with the same cross-linking agent. The rheological properties were studied using a Dynamic Shear Rheometer (DSR) with Temperature-Frequency Sweep Master Curves and the Multiple Stress Creep Recovery (MSCR) Test. The Master Curves showed that the polymer modification, up to 4% addition, increases the binder stiffness at high temperatures, which is a good indication of improved rutting resistance. The MSCR test showed improved percent recovery and compliance with increasing concentrations of SBS. To observe the effects of polymer addition on a microscopic level, the unaged binders were analyzed with the Environmental Scanning Electron Microscope (ESEM), finding that there were no significant changes with the level of polymer addition.

   8. Non- petroleum- Based Binders for Paving Applications: Rheological and Chemical Investigation on Ageing Effects

      Davide Dalmazzo, Ana Jiménez Del Barco Carrión, Lucia Tsantilis, Davide Lo Presti, Ezio Santagata

      Abstract

      The massive exploitation of non-renewable natural resources which has taken place in the last decade has led to significant global environmental concerns. In such a context, the use of non-petroleum-based binders for the construction of bound layers of flexible pavements can represent an effective solution to limit crude oil depletion. The research work presented in this paper focused on the effects of ageing on the rheological and chemical characteristics of a non-bituminous binder, indicated in the study as a “biobinder”, and a traditional neat bitumen selected as a reference material. Binders were analyzed in four ageing conditions obtained by making use of the Rolling Thin Film Oven and of the Pressure Ageing Vessel. Rheological behaviour of binders was investigated by means of oscillatory tests carried out in a wide range of temperatures and frequencies with a dynamic shear rheometer. Chemical structure was explored via Thin Layer Chromatographic analyses and Fourier Transform Infrared Spectroscopy. The experimental work demonstrated that mechanisms of ageing which are involved in biobinders completely differ from those experienced by petroleum-based binders. Concerns were expressed with respect to the applicability to non-conventional binders of currently available ageing techniques and of chemical characterization methods.

   9. Investigation into the Use of Reclaimed Asphalt Pavement in Asphalt Concrete

      Olumide Moses Ogundipe

      Abstract

      This paper reviews the recycling of reclaimed asphalt pavement (RAP). The review establishes the various methods of obtaining RAP which include milling, pavement demolition and plant waste. It also looks at the recycling methods which include: hot mix recycling; hot-in-place recycling; cold mix recycling; cold-in-place recycling and full depth reclamation. The benefits and challenges of recycling RAP were also considered. The laboratory study examines the Marshall properties of virgin asphalt concrete and the one containing 20%, 30%, 40%, 50%, 60%, 70% and 100%. The study reveals that the optimum amount of RAP that can be used is 60%. It concludes that recycling of RAP can be used in the asphalt concrete. Therefore, it recommends that for successful recycling of RAP in Nigeria, it is important to: evaluate the properties of RAP; perform enough pavement sampling to estimate variability of material properties; separate and identify by source large quantities of RAP obtained from different sources and commission research into the generation, management and recycling of RAP.

   10. Rheological and Mechanical Properties of HMA Containing Fly Ashes as Alternative Filler

       Rosa Veropalumbo, Nunzio Viscione, Francesca Russo

       Abstract

       This study defined the mechanical/volumetric properties and the environmental compatibility of bituminous mixtures containing fly ashes as alternative of traditional limestone filler. The research study is articulated in different steps as follows: (a) characterization of fly ashes according to EN 13043 Standard; (b) environmental compatibility analysis of mastics containing fly ashes by a leaching test; (c) stiffness evaluation of the mastics containing limestone and fly ash filler by static testing, as Delta Ring and Ball Test, and dynamic testing, as Frequency Sweep Test; (d) mechanical and volumetric characterization of asphalt concrete containing fly ashes and limestone filler starting from a phase of mix design of hot mix asphalt mixtures. The characteristics of stiffness of the bituminous mixtures has been evaluated on the optimum HMA through a dynamic test with a sinusoidal load. Then, the ability of two different HMA to endure a permanent deformation was evaluated by a Repeated Load Axial Test. The results has shown that mixtures of Hot Mix Asphalt with flying ashes as filler, compared to Hot Mix Asphalt containing limestone filler, is preferred in terms of mechanical performances and relevant environmental compatibility evaluated with the leaching test.

3. Future Trends in Asphalt Pavements

   1. Frontmatter

   2. Preliminary Study of an Energy Harvesting System for Road Pavements Made with Marginal Aggregate

      Marco Pasetto, Andrea Baliello, Antonio Galgaro, Elisa Mogentale, Anna Sandalo

      Abstract

      The progressive reduction of available energy resources and the continuous increase in demand are providing strong incentives for the use of renewable energies. Asphalt solar collectors are efficient energy harvesting systems for roads, able to extract thermal energy from pavements and convert the heat collected by their surfaces. Indeed, the possible reuse of waste materials in road construction, converted into valuable resources, has a strategic importance and could surely enhance the environmental sustainability of road pavement applications. This paper presents a preliminary experimental study aimed at evaluating the feasibility of a pipe-based energy harvesting system, which allows fluid circulation on a coil embedded in asphalt concrete manufactured with marginal aggregates. For this purpose, two-layer dense-graded asphalt slabs (AC8) were prepared in the laboratory, using different aggregate types (limestone and steel slag). A steel coil positioned at the interface was utilized to establish water circulation below the wearing course. The collected thermal energy was measured varying the water flow characteristics; the system was monitored through thermographic analysis while being subjected to a selected radiative power. Main results indicated that water flow rate was crucial in determining the temperature mitigation effect on asphalt concrete surfaces and the efficiency of the energy harvesting system. Some concerns about the operative approach were evinced (mainly related to the scale of the test); however, steel slag inclusion did not seem to compromise nor enhance the thermal conductivity of mixtures.

   3. Electric Energy Harvesting Systems from Urban Road Pavements: Analysis and Preliminary Simulation

      Sandro Colagrande, Gino D’Ovidio

      Abstract

      This paper discusses the topic of energy harvesting from urban roads illustrating an overview of new green road pavement integrated technologies to generate electric power. Two kinds of integrated road pavement technologies for clean electric energy harvesting compatible with loads and stresses generated by urban vehicular traffic were examined. The first concerns piezoelectric devices integrated into the road surface for generating electricity from the dynamic actions due to vehicular transit; the latter refers the photovoltaic panels distributed on the road surface for converting solar energy into electricity. Finally, preliminary systems performance simulations over an urban road section located in L’Aquila city (central Italy) with real environment and traffic conditions have been performed. Results are compared in terms of specific energy production. The presented work is a numerical study for understanding the potential of road energy harvesting technologies in real urban environment.

   4. Environmental Sustainability and Energy Assessment of Bituminous Pavements Made with Unconventional Materials

      Marinella Giunta, Marina Mistretta, Filippo Giammaria Praticò, Maria Teresa Gulotta

      Abstract

      The increasing sensibility towards the questions related to climate change has made the scientists and technicians aware of the need to incorporate the principles of sustainable development into the road construction sector. In this view, recycled materials in road pavements and technologies to decrease the overall carbon footprint have become more and more important. Based on the ISO14040 series, the overall purpose of this study is calculating, by means of a systemic approach, the life-cycle energy and the carbon footprint of road pavement solutions. To this aim, several alternatives in terms of bituminous mixtures (warm mix asphalt, reclaimed asphalt pavements, waste plastics) were considered. All the phases of pavement life from material production to end-of-life stages were taken into account. Results demonstrate that even if there is not a best alternative from all the angles of the analysis, however, the WMA technology, combined with the use of RAP, improves the pavement energy and environmental performance, involving a reduction in primary energy consumption and raw materials, and avoiding impacts for disposal.

   5. Reflectivity and Durability Assessment of Solar Heat-Blocking Pavement

      Masahiko Iwama, Tamotsu Yoshinaka, Shunsuke Nishioka, Hiroshi Murakami

      Abstract

      In recent years, there is growing awareness of environmental issues, such as global warming and climate change. As asphalt pavement covers approximately twenty per cent of urban areas, it is considered to be a factor in the “urban heat island phenomenon”. In order to tackle this problem from a paving perspective, solar heat-blocking pavement has been developed and applied as cool pavement technology to achieve the following benefits: a reduction in surface temperature and mitigation of urban heat. This paper describes a reflectivity and durability assessment of solar heat-blocking pavement in the laboratory and field, with the following conclusions being drawn from this study. With regard to the albedo characteristics, laboratory and field results show that the reduction in surface temperature is significantly related to the albedo characteristics. In terms of pavement durability in the laboratory and field, the surface of the solar heat-blocking pavement is strong enough for traffic loading, compared to dense-grade asphalt surfaces. Finally, the relationship between reflectivity and durability of solar heat-blocking pavement is highlighted through field monitoring results.

   6. Supply Curves Using LCA and LCCA for Conceptual Evaluation of Proposed Policies to Improve the Environment

      John T. Harvey, Alissa Kendall, Ali Butt, Arash Saboori, Mark Lozano, Maryam Ostovar

      Abstract

      Many changes are being proposed to reduce greenhouse gas emissions by a multitude of sources, with the proposals based to varying degrees on science, economics, the potential to grow markets or shrink the markets of competitors, regulatory strategies, and attractiveness based on the ability to easily communicate the idea to the general public. Identifying, quantifying, and then selecting among the many possible strategies to achieve GHG reductions is difficult, especially without a standardized approach for comparison. A promising approach, supply curves, that has been used at a national level for developing abatement strategies for GHG reduction is proposed for use in this paper. Some of the critiques of past use of supply curves are being addressed through the use of the principles of consequential life cycle assessment and life cycle cost analysis. Pilot studies currently underway for a large state road agency and local governments will provide initial feedback on the ability to use this approach at a conceptual level for initial prioritization of alternatives. Initial results indicate that sufficient data can be gathered in a reasonable amount of time to compare alternatives and that the results can be compared on a much more consistent basis than has occurred previously.