The growing interest in sustainable pavements has promoted the study of bio-based binders as alternatives to petroleum bitumen. Their durability is poorly understood, especially in saline environments. This study compares the rheological evolution of a commercial bio-based binder subjected to conventional thermal–oxidative ageing (RTFOT and RTFOT + PAV) and salt-fog ageing (SFA) conducted at 35 °C in a 5

The study of binder interaction is essential to understand the behavior of recycled mixtures containing RAP, especially under moderate temperature conditions. This work, part of a doctoral research project, proposes and validates a protocol to analyze diffusion between a fresh binder and an aged binder using a Dynamic Shear Rheometer (DSR). The method consists of evaluating the variation of the shear modulus over time at 35 ℃ in a structure composed of two binder layers. The diffusion process should lead to the formation of a gradient of binders’ concentration which evolves during the test. As the rheological properties depends on the binders’ concentration, they should change during the test. The results show a certain variation of the modulus over time and demonstrate the possibility of modeling the phenomenon.

Oil-rosin ester bio-based binders are attracting increasing interest in road infrastructure due to their renewable origin, promising performance, and potential for versatile applications. However, the ageing mechanisms of these binders are not well understood, especially regarding the individual contributions and interactions of the oil and rosin phases. This study investigates whether the ageing of the oil phase alone can account for the observed changes in binder viscosity over time, through a combined theoretical and experimental evaluation under two hypotheses: (1) no chemical interaction occurs between the oil and rosin phases, and (2) rosin esters do not undergo ageing. Four vegetable oils with distinct chemical profiles (palm, olive, sunflower, and linseed) were used to produce six bio-based binders incorporating three commercial rosin esters. Theoretical viscosities were estimated using Arrhenius Mixing Law and compared with experimental measurements after short-term and long-term ageing. The model accurately predicted viscosity only for short-term ageing in systems with stable rosins, while under or overestimations occurred in other cases. Both hypotheses were disproven, highlighting that oil ageing alone cannot explain binder behavior. The results further emphasize the strong influence of oil composition on ageing resistance and the stabilizing role of the rosin phase.

Lignin, a bio-based aromatic polymer and the main natural source of phenolic compounds has recently gained interest as a sustainable alternative to petrochemical-derived bitumen in asphalt mixtures. Most previous studies have focused on the wet incorporation of lignin into binders, often overlooking the influence of lignin type. This study investigates the dry incorporation of four technical lignins—two kraft lignins (KA, KB) and two lignosulfonates (LSA, LSB)—as filler replacement in asphalt mixtures. The lignins were characterized in terms of molecular weight, polydispersity, elemental composition, functional groups, and thermal properties. Binder content, particle size distribution, penetration, and softening point were measured on mixtures and recovered binders. Results show that lignin preferentially migrates into the bituminous phase rather than remaining in the filler fraction. The extent of this migration depends on lignin morphology, molecular weight distribution, and sulfur content, which affect its interaction with bitumen. These findings underline the importance of lignin type for asphalt applications.

Bio-based binders offer a potential solution for the availability issues of bitumen, though their aging behaviour may differ mainly due to higher oxygen content. This study aims to understand the aging resistance of model bio-based binders produced from various vegetable oils (palm, linseed, sunflower, olive) and rosin esters (Rosin A, B, C). A commercial bio-based binder was used for comparison and design. FTIR-ATR show no differences through lab aging, while DSR results reveal varying impacts after lab aging. The types of rosin esters and vegetable oils significantly affect aging resistance. Although the specific chemical characteristics of the rosin esters influencing aging remain unclear, a strong correlation exists between the iodine numbers of vegetable oils, indicating that oils with iodine numbers higher than 150 are unsuitable for bio-based binders. This paper provides useful information about bio-based binder component properties helping at developing materials that resist aging.

In the present paper, a lab technical study is proposed aiming at defining the recycling potential of Irish pavement materials using only a bio-material as added binder. The bio-binder used here is mainly made of a kraft paper industry residue, tall oil pitch by-products. It has been designed to replace totally conventional petroleum bitumen. In order to assess the applicability of this alternative solution, objectives are to understand: i) the rejuvenating effect of the bio-binder on the old bitumen, ii) the ageing behaviour of this particular blend, iii) the mechanical behavior of mixes made of reclaim asphalt and the bio-binder. This study shows, at lab scale, a very good ageing resistance of the bio-binder blended with old bitumen and good performances of the corresponding mixes. Hence, it is possible to recycle pavement materials without adding petroleum bitumen. The bio-binder used here could be used in the context of Irish pavement construction expecting a materials durability at least as good as conventional materials and a reduced carbon footprint.

An optimal wearing course should provide safety, comfort, and durability while minimizing the impact on the environment. Some of those functions are antinomic and thus difficult to integrate considering the current state of the art. A large experimental program was carried out, involving the evaluation of 10 asphalt mix designs. Two innovative acoustic mixes, plus a traditional one, were selected from this program. Lab experiments demonstrated that the grading curves and void structure of these new mixes lead to a good compromise between acoustic performance, skid resistance, durability, and rolling resistance. A full-scale experiment was then carried out on an accelerated pavement testing facility, to validate the good behavior highlighted by laboratory studies embodied by the enhancement of acoustic absorption (peak values of 0.86 and 0.78 for the two innovative acoustic mixes, 0.39 for the reference mix) for equivalent mechanical properties. After the experiment, the properties of the test sections (mechanical properties, surface roughness, skid resistance, and acoustic properties) were evaluated. The results confirmed the good durability of the mixes under traffic loading.

Rolling resistance is a physical phenomenon related to the dissipation of energy occuring when a tire rools on a road pavement. This loss of energy generates forces opposed to the vehicle movement, which in turn increase fuel consumption. Several factors affect rolling resistance among them, pavement surface texture. Nevertheless, there is a need of identifying relevant texture parameters that can explain rolling resistance evolution. This paper presents a laboratory based study performed on sixteen different pavement mixes. Texture measurements and rolling resistance measurements using a novel test methodology are realized. The analysis of the results demonstrated that parameters such as RMS (Root Mean Square height) and Smc (Inverse Areal Material Ratio) appear as the most correlated with rolling resistance, which can be explained by the fact that an increase in roughness entails an increase of the energy losses by indentation phenomenon. This study also demonstrated that a limit is reached on the direct correlation between texture parameters and rolling resistance coefficient.

This study presents the results of direct tensile tests performed at three different temperatures on mixtures containing crumb rubber (CR). These tests were conducted on GB5® mixtures, which included varying percentages (0

This study was conducted to assess the time evolution of the linear viscoelastic behaviour of bituminous mixtures containing crumb rubber added by dry process. For this purpose, three mixtures containing 0

Cold recycling techniques provide an eco-friendly solution for restoring aged asphalt pavements, minimizing non-renewable material usage. Limited to low-traffic areas, its effectiveness depends on weather and seasonality. Various research focus on bio-sourced materials to substitute bitumen, but ensuring compatibility and solving aging issues are crucial for manufacturing durable pavements with these alternatives. The aim of this work is to validate the use of biosourced emulsion for cold in-place recycling with the same level of performance as conventional bituminous solutions. The effectiveness of the mixtures was assessed using a simple compression test, considering two different conditions (temperature of 18 ℃/relative humidity of 50

Pervious pavement- and wall-watering was studied at a 100 m2 pilot site in Hy'eres (France). Surface temperature monitoring was conducted continuously with an infrared camera to assess watering's cooling effects and duration as well surface drying time for the concrete fa,cade and the pervious pavement. Watering was conducted every hour for 15 min from 8 am to 6 pm in summer 2021. Results show up to 14.3 degrees C surface temperature reductions for pervious pavementwatering, and up to 8.4 degrees C of cooling for wall-watering applied to a South-facing wall. For shaded surfaces, maximum cooling is limited to 5 degrees C, whether vertical or horizontal. Between watering cycles, the vertical and impervious wall surface dries in approximately 15 to 20 min. For the pervious pavement, drying time varies along the surface. While certain areas, downstream, don't dry between watering cycles, others dry in 25 to 35 min. These variations depend on the relative height of the considered zone along the pavement slope, as well as the pavement's material and topographical irregularities. Residual cooling effects are observed the following night until the next morning for both pavement- and wall-watering, in the order of 3.5 degrees C and 1 degrees C at 6 am, respectively. Results further illustrate the higher efficiency of urban watering solutions for surfaces in direct sunlight.

This paper conducts a comprehensive Life Cycle Assessment (LCA) of bio-reused asphalt pavements, focusing on three distinct technologies. The assessment evaluates various environmental impact categories, including climate change (global warming potential), metal depletion, freshwater consumption, freshwater eutrophication, ionizing radiation, land use, and terrestrial ecotoxicity. Comparisons against a baseline reveal significant differences in impact category indicators. Findings indicate that all technologies demonstrate a reduction in the climate change indicator (global warming potential) when considering biogenic carbon. Similarly, there is a consistent decrease observed in the metal depletion indicator across all technologies. However, an increase is noted in several impact category indicators, including freshwater consumption, freshwater eutrophication, ionizing radiation, land use, and terrestrial ecotoxicity, compared to the baseline. Of particular importance is the identification of land use as the most critical impact category indicator when compared with the baseline. This highlights the necessity of using waste biomass or biomaterials which are by-products from other industries to optimize the environmental performance of bio-reused asphalt pavements.

Traditional deicing methods such as chemical and mechanical deicing can have high environmental/economic impacts and lack efficiency. To provide an alternative, a new material has been developed that can quickly deice road surfaces through electrical resistance heating. This heating paint contains 20

The goal of an optimal wearing course is to provide safety, comfort, and resistance while minimizing the impact on the environment. It must have excellent skid resistance, durability, and acoustic properties. Some of those functions are antinomic and thus difficult to integrate into the current state of the art. The module “Enrobé du Futur” (Future Asphalt Mix) of the I-STREET (Systemic Innovation serving Ecological and Energy Transitions in road transport infrastructures) project, led by Ademe, the French agency for environmental transition, aims to develop and characterize a multifunctional wearing course. A large experimental program was carried out, involving the evaluation of 10 asphalt mix designs. Two innovative acoustic mixes, as well as a traditional one, were selected from this program. A full-scale experiment was then carried out on the fatigue carousel of Université Gustave Eiffel, an APT (accelerated pavement testing) facility located on the Nantes campus in France, to validate the good on-site behavior of selected materials. After the application of 200,000 cycles of 65-kN half-axle loads, simulating 10 years of urban traffic, the final properties of the test sections were evaluated, including rutting, surface characteristics, and acoustic properties. The APT results confirmed the good durability of the mixes properties under traffic loading.

The environmental challenges facing society today are forcing the road construction industry to tackle the twin challenges of decreasing consumption of nonrenewable raw materials and limiting its carbon impacts. Yet, roadworks can deliver some genuine environmental benefits, along with low greenhouse gas emissions, by becoming a carbon sink. Recycling very high proportions of road construction materials and gradually incorporating bio-based products into their composition is now a proven solution. To this end, Eiffage Route has developed a range of plant-based binders, suitable for recycling, which incorporate a high proportion of materials recovered from existing pavement. This article reviews the so-called Biophalt innovation that won the 2019 award presented at the Road and Street Innovation Committee established by the Transport Infrastructure Department of the French Ministry of the Ecological Transition. It consists of a warm mix asphalt (WMA), including a high amount (>30 %) of recycled asphalt and a plant-based patented binder, suitable for any type of traffic. Both environmental and mechanical performances of Biophalt, assessed through SEVE TP modeling and several mix design studies carried out in the framework of different jobsites, are presented. They underline the “carbon sink” properties of the bio-based WMA as well as its compliance with standards defined by the norms of the French asphalt mix design method. It thus demonstrates Biophalt’s ability to combine both sustainability and excellent mechanical characteristics.

In this study, the influence of crumb rubber added by dry process on the dissipative properties of bituminous mixtures has been investigated. Six mixtures were tested: two reference mixtures without crumb rubber were produced, one containing a pure binder and the other one containing an SBS-modified binder. Four other mixtures containing 2 % and 4 % (in mass) of crumb rubber and the same two mentioned binders were also produced. First, complex modulus tests were carried out at different frequencies and temperatures and for an axial strain amplitude of 50 mu m/m. The 2S2P1D analogical linear viscoelastic model was used to model experimental data. From these results, the dissipated energy during one sinusoidal loading cycle was calculated, both for constant strain amplitude loading and for constant stress amplitude loading. Simulations at constant strain amplitude show lower energy dissipation for bituminous mixtures containing 2 % and 4 % CR and the SBS-modified bitumen with respect to the corresponding reference mixture without CR. However, the opposite is found at constant stress amplitude. Mixtures containing pure bitumen and CR show lower dissipated energy for any loading mode. Numerical simulations were carried out to determine energy dissipation at the scale of a pavement structure. The linear viscoelastic properties determined experimentally for the different materials were implemented in a finite element model to perform the calculations in the frequency domain. Results show that pavements made with bituminous mixtures containing CR added by dry process dissipate more energy with respect to the reference mixtures without CR.

The main results of the French collaborative project Improvmure, funded by the National Research Agency are presented. A very wide study was performed on bituminous mixtures produced on experimental sites or in laboratory at different scales (semi-industrial process or lab process). Objectives were to evaluate the influence of the recycling rate (0%, 40% and 70%), the number of successive recycling cycles (from 1 to 3 cycles), and the manufacturing process (hot mix or warm mix using additives or foamed bitumen). The impact was studied in laboratory on the emitted fumes during the production process, on the properties used for mix design (compactability, water sensitivity, complex modulus at 15 degrees C/10 Hz, fatigue), on advanced thermomechanical behaviour (linear viscoelasticity, crack behaviour at low temperature, crack propagation) and on surface properties (skid resistance). The paper gathers many valuable results, showing the possibility to recycle bituminous mixtures multiple times, at high rates and with warm manufacturing process.

In the context of global warming, cities need to be prepared to limitate thermals stress in city, especialy during heat wave, when the it’s become to be a health issue. This study is focused on evaluating the cooling effects of a pervious, ochre pavement combined with pavement-watering in response to the urban heat island effect and extreme heat events to offering permanent cooling effect and stronger effect with water mitigation, althougth punctual. A micro-climatic study was conducted following a Before After Control Impact (BACI) design to evaluate the effect of the new pavement and watering on pedestrian heat stress during typical heat-wave conditions. The surface temperature of the 100 m2 test site was also monitored. Since the pervious pavement have a low albedo, we see no significant effect compared to standard pavement althougth with the use of water we are able to see a cooling effect of − 15 °C on the surface imputing a − 1 °C refreshing effect on air temperature at 1.6 m height.

The use of bio-oils and biobinders in recycled asphalt mixtures have attracted the attention of researchers and contractors in the pavement field because they allow the incorporation of higher amounts of recycled material while reducing the consumption of new asphalt binder. However, inclusion of these biomaterials in the blends has led to concerns about the overall performance of the recycled mixture and prompted investigations to identify the proportions required to optimize restoration of the aged binder properties in the recycled material. In this context, this paper presents the verification of blending charts based on high performance grade (HPG) temperature in relation to the restoration of the HPG values and rutting susceptibility for one commercial plant-based binder used as recycling agent in two Brazilian aged asphalt binders. The results showed that to optimize the rejuvenating effect of this biobinder, blending charts based on nonrecovery creep compliance were more efficient. The biobinder was also found to restore, and even improve, the initial properties of the aged binders, which showed the potential of this biomaterial to be used as an effective recycling agent.