Impact-absorbing pavements (IAPs) may be used as novel sidewalks and bike lanes surface layers to decrease fall-related injuries among vulnerable road users (VRUs). Therefore, a cold-made, highly rubberised asphalt mixture (56% recycled rubber in the total volume of the mix) was developed in the laboratory, and the process was then upscaled, permitting its construction on a trial site. Both laboratory and on-site tests facilitated the evaluation of the material’s mechanical properties, impact-absorption capabilities, and frictional behaviour. The field trial enabled a comprehensive assessment of the material’s performance after six months of usage by pedestrians and cyclists on a hybrid segment. Additionally, evaluations were conducted after six, fifteen, and twenty months. The results confirmed the possibility to produce and lay a cold, highly rubberised paving material with valuable impact-attenuation performances. The mechanical analysis has shown the material’s elastic behaviour and its capability to carry uniaxial compression stress leading to a 5% strain of the total height without losing its properties. Furthermore, the critical fall height (CFH) values exhibited a sixfold increase compared to conventional asphalt, thereby reducing the severity of potential injuries. In terms of durability, the pavement’s overall effectiveness remained significant even after six, fifteen, and twenty months of use. The study demonstrated the capability to cover and fill holes and damaged portions using the same rubberised and cold mixture, a crucial aspect concerning the material’s future and maintenance considerations. 

Objective: Vulnerable Road Users (VRU), including pedestrians and cyclists, are generally the least protected road users and are frequently missed in the planning process of preventive measures. Rubberized asphalt mixtures were originally developed as a possible environmentally friendly solution to recycle the End-of-Life Tires while making the pavements more durable. The objective of the current study was to explore the effects of increasing the rubber content of the common rubberized asphalt mixtures in reducing the head injuries risk for VRUs. Method: To achieve this purpose, four different sample series with 0, 14, 28, and 33 weight percent rubber in each were tested. A compressive test without permanent deformation and one with failure were performed on each sample series. The mechanical behavior of each set was modeled using a MAT_SIMPLIFIED_RUBBER material model in LS-Dyna and validated against a standard Head Injury Criterion (HIC) drop test. Ultimately, previously low-speed accident reconstructed cases, a bicycle and a pedestrian one, were used to assess the effect of varying the rubber content on reducing the head injury risk. Results: In the bicycle accident case, the risk of skull fracture was reduced from 0.99 to 0.29 when comparing the non-rubberized asphalt mixture with the 33% rubber mixture. In the same accident case, the risk of concussion, evaluated using the logistic regression method, was reduced from 0.97 in the non-rubberized mixture to 0.81 in the 33% rubber mixture. The initial conditions, linear and rotational velocities, were lower for the pedestrian case compared to the bicycle case (the bicycle case was more severe compared to the pedestrian case), which led to lower strains in the pedestrian case. In the pedestrian accident case, the risk of skull fracture was reduced from 1.00 in the non-rubberized mixture to 0.63 in the 33% rubber mixture, while the risk of concussion was reduced from 0.64 to 0.07. Conclusion: The rubberized asphalt mixtures could reduce the head injury risk for the studied cases when the rubber content in the asphalt mixture increases. © 2022 The Author(s). 

Cyclists, pedestrians and elderly people’s specific needs in urban road infrastructures are often neglected. They rarely benefit from safety measures or innovations. Inspired by playgrounds and aiming to reduce vulnerable road users (VRUs) injuries, the development of the rubber-based Impact-Absorbing Pavements (IAP) offers a possibility to rethink the design of urban pavements and address safety on roads, which constitutes a major challenge in terms of attaining more sustain-able, resilient, and safe cities. Therefore, bituminous mixtures with four different crumb rubber con-tents, 0%, 14%, 28%, and 33% (in total weight), were produced by partial aggregates substitution using the dry process. After the assessment of the geometrical and volumetric properties, the mechanical performances were evaluated. Finally, the samples were tested to measure the abrasion and impact attenuation with the well-known Head Injury Criterion (HIC), at different temperatures from −10 to 40 °C, to obtain a wide range of values referring to possible weather conditions. A significant effect of the rubber percentage and layer thickness on impact attenuation was observed. All observations and results confirm the feasibility of the IAP concept and its positive effect on future injury-prevention applications. © 2021 by the authors.

The substitution of mineral aggregates with crumb rubber (CR) from waste end‐of‐life tires (ELTs) in the asphalt concretes, has been considered a sustainable paving industry approach. The rubber has been used to construct pavements with proven enhanced resilience and improved durability. However, some issues related to the rubber’s surface adhesion or swelling may arise with these practices and generate complications (binder consumption, temperatures, mixing times). One possible solution to overcome the materials’ compatibility problems is to pre‐treat the CR’s surface before its incorporation into the asphalt mixes to allow a surface functionalization that can enhance coverage and cohesion inside the mixes. The physical treatments using radiations‐based beam are already exploited in the plastic recycling industries avoiding the use of chemicals in con-siderable amounts. Such treatments permit the recovering of large quantities of polymer‐based materials and the enhancement of interfacial properties. This article provides an overview of existing surface treatments of polymers and especially rubber, including gamma ray, UV‐ozone, micro-waves, and plasma. Several studies have shown an overall improvement of the rubber surface’s reactive properties due to contaminant removal or roughness enhancement attributed to cross‐link-ing or scission reactions occurring on the rubber’s surface layer. With those properties, the asphalt mixes’ phase stability properties are increased when the pre‐treated rubber is incorporated. The treatments would permit to increase the CR quantities, yet reduce the layer stiffness, and improve the durability and the sustainability of future advanced road pavements. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Aggregation of ice on electrical cables and apparatus can cause severe equipment malfunction and is thus considered as a serious problem, especially in arctic climate zones. In particular, cable damage caused by ice accumulation on railway catenary wires is in wintertime a common origin for delayed trains in the northern parts of Europe. This study examines how resistive heating can be used for preventing formation of ice on metallic, non-insulated electrical cables. The heat equation and the Navier Stokes equations were solved simultaneously with FEM in 3D in order to predict the cable temperature as function of external temperature, applied voltage, wind speed, wind direction, and heating time. An analytical expression for the heat transfer coefficient was derived from the FEM simulations and it was concluded that the influence of wind direction can typically be neglected. Experimental validation measurements were performed on Kanthal cables in a climate chamber, giving temperature increase results in good agreement with the simulation predictions. The resistive heating efficiency, i.e. the ratio between applied electrical energy and resulting thermal energy, was found to be approximately 68% in this particular study.

Fluorocarbon, organosilicon, and hydrocarbon plasma coatings were used to modify the surface permeable pigment-coated paper, and their impact on UV-varnish absorption was investigated. According to mercury porosimetry results, the plasma coatings had no influence on the porous structure of the paper. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) results showed characteristic surface chemical compositions for each plasma coating. The fluorocarbon plasma coating increased the UV-varnish contact angles significantly, whereas the hydrocarbon plasma coating had no clear influence. When the UV varnish was applied with a flexography unit including nip pressure, the role of surface chemical composition seemed to become minimal. The viscosity of the UV varnish was shown to impact the absorption rate with and without external pressure.