Integrating Circularity in the Sustainability Assessment of Asphalt Mixtures

Rising concerns about the impacts that the road engineering industry is imposing to the environment have redirected national road authorities to firmly re-consider the sustainability implications of their operations. Lately, though, sustainability has established a forceful correlation with the Circular Economy and its principles. The road engineering industry, therefore, is moving towards more circular approaches. However, this is occurring without the assessment of the potential impacts of such a transition. For this reason, in this study, a composite indicator, namely, Environmental Sustainability and Circularity indicator (ESCi), for investigating the potential effects that increased circularity could have at the environmental sustainability of asphalt mixtures is developed. It can be utilized as a decision-making support tool from stakeholders involved in both asphalt mixture production and road pavement management. In addition, in this study, four asphalt mixtures with different percentages of Reclaimed Asphalt (RA) were assessed in terms of their “cradle-to-gate” environmental impacts and circularity, by means of Life Cycle Assessment, and Material Circularity Index, respectively. Their fatigue and permanent deformation performances play a key role in the assessment and distinctive results obtained for the asphalt mixtures with increasing RA% and thus, significant environmental benefits and increased circularity are observed after specific RA% threshold

Le vibrazioni in campo ferroviario: analisi f.e.m. dell’interazione convoglio-sovrastruttura-terreno

This paper describes the formulation and application of a finite element method model that simulates the generation and propagation of train-induced vibrations into track-ground system. The F.E.M. model accounts for the interaction between ground, railway, shape of cross-section and train speed. The aim of this research is the evaluation of the influence of each factor on vibrational phenomena

Indagine sperimentale sui segnali sonori all’interno dei rotabili per la diagnosi dello stato dell’armamento ferroviario

The maintenance of track provides an relatively frequent operations. A good maintenance-planning allows to reduce the interference between rail traffic and maintenance operations. It is necessary so to use a monitoring system of track conditions. In this paper is showed an indirect monitoring system that correlates track conditions and typical spectrum of in-cab noise. The first results of experimental survey are reported

Studio di conglomerati bituminosi con granulato di gomma proveniente da pneumatici dismessi

La ricerca di conglomerati bituminosi di elevate prestazioni sovente si associa allo studio delle implicazioni ambientali che la produzione, la posa in opera e l’esercizio di tali materiali comportano. Un aspetto assai importante, in tal senso, è l’opportunità che alcune modalità produttive offrono in termini di un ridotto consumo di inerti e del contestuale impiego di materiali destinati a discarica che, invece, vengono inseriti in processi di riciclaggio. È questo il caso della gomma proveniente dal riciclaggio industriale di pneumatici dismessi che, negli Stati Uniti ed in Canada, è divenuta una fonte sostanziosa per la realizzazione di conglomerati bituminosi. La presente ricerca, dopo una preliminare e sintetica descrizione del granulato di gomma e delle sue proprietà chimico-fisiche, si propone di evidenziare sperimentalmente il comportamento meccanico di conglomerati bituminosi per strati di base confezionati in laboratorio con l’aggiunta di questo componente, mediante i noti processi Dry e Wet, elaborati e combinati secondo opportuni criteri metodologici. In particolare l’indagine verte su prove inserite nell’attuale normativa italiana, con l’obiettivo di pervenire ad un quadro rappresentativo dell’influenza del granulato sulle caratteristiche meccaniche analizzate

Pavement Management System model using a LCCA- microsimulation integrated approach

The maintenance and the rehabilitation of the urban road pavements are not often based on systematic program and scheduling but rather on emergency or on other not identified reasons. Moreover the Life Cycle Cost Analysis (LCCA), the only peculiar procedure for the management pavement, finds its own application for highway and motorway, even if it is possible to search the best investment for the urban interstate and arterials. By the light of the quantity of the involved resources, it seems necessary to define an operative methodology for programming the maintenance and rehabilitation activities for the urban pavement. The paper is oriented towards the development of a multidisciplinary approach to make decision on management of urban pavement using the basic concepts of the LCCA and micro-simulation model to define a scheme of work zone that minimizes the delay on the traffic flow. The best rehabilitation strategy should be characterized by the lowest users’ cost that depends on the time period of the work zone, which is conditioned by both own scheme and the provided treatment, and on “social cost” as increased travel time for queue generation . Different scenarios for different work zone plans were developed and a micro-simulation model was used to assess increased total travel time of a traffic flow within the maintenance area. In this work an analysis by means of the above mentioned approach was carried out on real scenario in the city of Palermo in order to point out the several frames of the adopted methodolog

Investigating the Viability of Multi-Recycling of Asphalt Mixtures through a Preliminary Binder Level Characterization

The incorporation of reclaimed asphalt (RA) in hot mix asphalt mixtures is widely considered a sustainable solution for road infrastructure development. Under the scope of the circular economy (CE), the multiple recycling capability of RA has to be assessed in order to ensure its performance at each recycling cycle and also its viability with different additives. The performance of asphalt mixtures with RA strongly depends on the type of rejuvenator, binder, and their degree of blending in the mix. For this reason, it is essential to know the properties of the aged binder extracted from RA to better understand its rheological properties and optimal dosage of rejuvenation to design a satisfactory blend design for the recycled mixture. To analyse the multi-recycling potential of the recycled mixture with high RA content, it is imperative to study its characteristics at every recycling cycle. Therefore, in this study, a preliminary binder-scale study is carried out to better understand the ageing, rejuvenating effects and morphological changes that occur on the bituminous binders at every recycling cycle. The study has been conducted on a RA binder, extracted from RA from a rural road in Italy and the simulation of multiple recycling is conducted through a laboratory ageing protocol on both binder and asphalt mixture scales. The long-term binder level ageing is performed by a pressure ageing vessel (PAV) after the short-term ageing by the rolling thin film oven test (RTFO). The asphalt mixture ageing is performed through a protocol similar to the National Cooperative Highway Research Program (NCHRP) and the aged binder is extracted from the mixture for further investigations. Multiple recycling is simulated by repeating the ageing procedure after rejuvenating both the aged binder and aged mixture up to the amount of recycling needed for the study. The rheological properties of the aged binder obtained from both binder-scale and mixture-scale ageing methods are evaluated using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). Moreover, the morphological changes that occurred are analysed using SARA (saturates, aromatics, resin and asphaltenes) fractionation and atomic force microscopy (AFM). The results of the study can help towards answering the uncertainties regarding the performance of high RA% in asphalt mixtures and establishing its viability in multi recycling towards the full-scale implementation of this sustainable approach

Exploiting Data Analytics and Deep Learning Systems to Support Pavement Maintenance Decisions

Road networks are critical infrastructures within any region and it is imperative to maintain their conditions for safe and effective movement of goods and services. Road Management, therefore, plays a key role to ensure consistent efficient operation. However, significant resources are required to perform necessary maintenance activities to achieve and maintain high levels of service. Pavement maintenance can typically be very expensive and decisions are needed concerning planning and prioritizing interventions. Data are key towards enabling adequate maintenance planning but in many instances, there is limited available information especially in small or under-resourced urban road authorities. This study develops a roadmap to help these authorities by using flexible data analysis and deep learning computational systems to highlight important factors within road networks, which are used to construct models that can help predict future intervention timelines. A case study in Palermo, Italy was successfully developed to demonstrate how the techniques could be applied to perform appropriate feature selection and prediction models based on limited data sources. The workflow provides a pathway towards more effective pavement maintenance management practices using techniques that can be readily adapted based on different environments. This takes another step towards automating these practices within the pavement management system

Developing a framework for using Structure-from-Motion techniques for Road Distress applications

On Urban road networks, road agencies need to quickly identify road pavement distresses in order to identify appropriate maintenance and rehabilitation strategies. This is integral as agencies are plagued with financial and time constraint issues. There have been several attempts over the last few years to identify new solutions and techniques to solve these issues. Several of these have shown merit and accuracy in identifying distresses. However, the techniques in many instances are not correlated to available distress identification standards. One of the considered techniques is the use of Structure-from-Motion, which tries to recreate 3D distress models for identification and analysis. This paper considers this methodology and attempts to integrate it with measurement requirements used by distress manuals to illustrate how the technique can be used with real-world industry standards and practices. Case studies of different measurement types, on an urban road in Palermo, Italy, are considered. The results from these examples show that the technique replicates pavement distresses of varying measurement requirements and the paper presents a workflow of how it can be utilized to help optimize the pavement management system and their connections to different distress identification manuals worldwide

THE DIAGNOSIS OF ROAD SURFACE DISTRESSES THROUGH IMAGE-BASED MODELING TECHNIQUES. EXPERIMENTAL SURVEY ON LABORATORY-RUTTED SAMPLES

In the past few years, there has been a drastic increase in the use of image-based modeling (IBM) techniques to create high quality, reality-based 3D models. The low costs of these techniques, as well as their attractive visual quality, have led many researchers and professionals to invest their energy and resources in several tests. IBM is rarely used in the field of road surface distresses as diagnosis is usually performed using other techniques and devices. Road safety statistics reveal that about a half of the total number of accidents occur mainly due to the deterioration of the pavement. The goal of effective road network management is often incompatible with economic resources designated for maintenance and rehabilitation. For this reason, IBM diagnosis of distresses seems necessary in order to both increase the level of road safety and to avoid incorrect interventions and treatments of road pavement. One of the strengthens of multi-view stereo techniques is the possibility to capture millions of points in a very short time, and to produce a 3D, textured polygonal model that can easily be used for visualizing and communicating digital assets. Our goal was to implement the IBM techniques on a laboratory-rutted sample and to verify the metric accuracy of the model and its validity for the distress diagnosis in terms of severity (rut depth). In order to assess the IBM technique, we compared its 3D model to the blue LED 3D scan (Artec Spider) of the same rutted sample

A dynamic model of ballasted rail track with bituminous sub-ballast layer

The bituminous sub-ballast layer within the ballasted rail track allows some mechanical and environmental advantages. An analytical model of a ballasted rail track with sub-ballast layer has been proposed by considering the rail as viscous-elastic continuous beam discretely supported, at four levels of elasticity. The model was used to compare the mechanical performance of both ballasted track with and without bituminous sub-ballast layer. The results confirmed that the bituminous sub-ballast layer reduces the dynamic forces on the ground and achieves the technical objectives as reduction of ground borne vibrations and increase of the design life of the rail track