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

Increasing the Circularity of asphalt mixtures: Integrated Sustainability and Circularity Assessment as a progress monitoring tool towards more Circular and Sustainable asphalt pavements

Sustainability and Circular Economy (CE) are two concepts that lately have been profoundly linked to each other. The road engineering industry has gradually been adapting practices that are considered both circular and sustainable. However, not all of these practices entirely consider the whole life environmental and circularity assessment and implications of asphalt mixtures.; which in turn leads to doubtfully circular and sustainable approaches. For this reason in this thesis, after analysing the ways that National Road Authorities implement and communicate CE through questionnaires and web searches, a Material Circularity Index quantifying framework, based on the proposed methodology of the Ellen MacArthur Foundation, for asphalt mixtures was developed to assess their circularity. Within this framework, aspects relevant to the mechanical performance of the asphalt mixtures have also been incorporated. Furthermore, in order to also include the aspect of sustainability, a combined circularity and environmental sustainability assessment framework and indicator for asphalt mixtures with reclaimed asphalt was developed; by utilising the Material Circularity index methodology and the well-established framework of Life Cycle Assessment. The development of the frameworks was followed by case studies that verified the models and projected their usefulness towards more informed decisions when it comes to more circular and sustainable asphalt mixtures. Results of this thesis highlight that National Road Authorities are still facing a plethora of challenges towards the implementation and communication of CE, along with lack of knowledge and incentives. They do implement CE principles such as recycling and preventive maintenance, but they do not utilise metrics to assess their performance. By utilising the proposed indicator and frameworks circular and sustainable recommendations could be drawn along with a knowledge development map for the involved stakeholders. Most importantly, it was deduced that practices that are considered sustainable and highly circular, after the combined sustainability and circularity assessment , were actually found not to be what believed so far. Thus, when it comes to asphalt mixtures and their life cycles, during the decision-making process, each CE-related action must be thoroughly investigated case by case.Sustainability and Circular Economy (CE) are two concepts that lately have been profoundly linked to each other. The road engineering industry has gradually been adapting practices that are considered both circular and sustainable. However, not all of these practices entirely consider the whole life environmental and circularity assessment and implications of asphalt mixtures.; which in turn leads to doubtfully circular and sustainable approaches. For this reason in this thesis, after analysing the ways that National Road Authorities implement and communicate CE through questionnaires and web searches, a Material Circularity Index quantifying framework, based on the proposed methodology of the Ellen MacArthur Foundation, for asphalt mixtures was developed to assess their circularity. Within this framework, aspects relevant to the mechanical performance of the asphalt mixtures have also been incorporated. Furthermore, in order to also include the aspect of sustainability, a combined circularity and environmental sustainability assessment framework and indicator for asphalt mixtures with reclaimed asphalt was developed; by utilising the Material Circularity index methodology and the well-established framework of Life Cycle Assessment. The development of the frameworks was followed by case studies that verified the models and projected their usefulness towards more informed decisions when it comes to more circular and sustainable asphalt mixtures. Results of this thesis highlight that National Road Authorities are still facing a plethora of challenges towards the implementation and communication of CE, along with lack of knowledge and incentives. They do implement CE principles such as recycling and preventive maintenance, but they do not utilise metrics to assess their performance. By utilising the proposed indicator and frameworks circular and sustainable recommendations could be drawn along with a knowledge development map for the involved stakeholders. Most importantly, it was deduced that practices that are considered sustainable and highly circular, after the combined sustainability and circularity assessment , were actually found not to be what believed so far. Thus, when it comes to asphalt mixtures and their life cycles, during the decision-making process, each CE-related action must be thoroughly investigated case by case

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

Towards More Sustainable Pavement Management Practices Using Embedded Sensor Technologies

Road agencies are constantly being placed in difficult situations when making road maintenance and rehabilitation decisions as a result of diminishing road budgets and mounting environmental concerns for any chosen strategies. This has led practitioners to seek out new alternative and innovative ways of monitoring road conditions and planning maintenance routines. This paper considers the use of innovative piezo-floating gate (PFG) sensors and conventional strain gauges to continuously monitor the pavement condition and subsequently trigger maintenance activities. These technologies can help develop optimized maintenance strategies as opposed to traditional ad-hoc approaches, which often lead to poor decisions for road networks. To determine the environmental friendliness of these approaches, a case study was developed wherein a life cycle assessment (LCA) exercise was carried out. Observations from accelerated pavement testing over a period of three months were used to develop optimized maintenance plans. A base case is used as a guide for comparison to the optimized systems to establish the environmental impacts of changing the maintenance workflows with these approaches. On the basis of the results, the proposed methods have shown that they can, in fact, produce environmental benefits when integrated within the pavement management maintenance system

Investigating the Multi-Recyclability of Recycled Plastic-Modified Asphalt Mixtures

Although the benefits of asphalt recycling have been scientifically proven and several best practices are being implemented, further research is required in specific and specialized areas. One of these circumstances is the recycling of Reclaimed Asphalt Pavements (RAPs) that contain asphalt modifiers such as elastomers and/or plastomers. Following the principles of the circular economy and considering the sustainability implications of asphalt mixtures, this paper deals with the multi-recyclability of asphalt mixtures containing 50% RAP with and without a recycled plastic asphalt modifier and rejuvenating agent. The recycled plastic asphalt modifier was made of hard recycled plastics and was introduced to the mixture via a dry method. The research focuses on the characterization of binders via conventional, rheological, and chemical analysis. To control the consistency and variables of the mixtures, the RAP was produced artificially in the laboratory following an ageing protocol for loose asphalt mixtures. According to the obtained results, at all three cycles of binder recycling, comparable properties for (i) the extracted binders from the recycled plastic-modified asphalt mixture, (ii) the extracted binders from the control un-modified mixture, and (iii) the reference bitumen 50/70 were obtained. This was even noticed when a nearly similar quantity of the rejuvenator was needed during the rejuvenator optimization process. Overall, it can be deduced that from the binder-scale point of view, the mixture containing the introduced recycled plastic additive could be recycled for multiple life cycles without any degradation of its mechanical and physical properties

Understanding the current state of practice in the construction and demolition waste sector through the lenses of circular economy: The Italian recycled materials market for the road construction sector

Construction and demolition waste (CeDw) is mainly produced during the construction, demolition, or renovation activities of civil engineering structures and it accounts for a remarkable amount of the total C&Dw generated, as it is estimated to be around 30%. This proportion differs between countries belonging to different types of economies and tends to be greater in countries with developing economies reaching 74% of total annual production. There is a plethora of applications that C&Dw can be used for under a circular economic model and in this research a focus is being given in the exploitation of C&Dw within the pavement engineering sector, and more specifically, in the utilization of said waste in road earthworks. Circular Economy can act as a steppingstone towards the uptake of C&Dw recycling and exploitation. To understand the state of practice that exists, a market and an implementation analysis have been conducted in Italy. The current applications of C&Dw recycling into road projects were analyzed along with the existing regulations, and local producers. The results projected the various challenges faced by the involved stakeholders, along with the barriers that hinder the wide recycling of C&Dw in road engineering projects. Finally, the proposed national action plans are analyzed and the future potential exploitation of C&Dw is put into context. The future of the specific research is going to involve a full scale, on-site implementation of C&Dw in a defined road segment

A Top-Down Approach Based on the Circularity Potential to Increase the Use of Reclaimed Asphalt

Resource depletion and climate change, amongst others, are increasingly worrying environmental challenges for which the road engineering sector is a major contributor. Globally, viable solutions that comply with the principles of circular economy (CE) are being investigated that can replace conventional asphalt mixtures in a post-fossil fuel society. The use of reclaimed asphalt (RA) is a widely used and well-established method to reduce the environmental and economic impacts of asphalt mixtures while increasing their circularity. However, RA's market supply and demand have not yet been systematically analyzed and established. Moreover, the actual circularity potential and the opportunity of re-circulating RA in a closed-loop model have not yet been methodically defined. To address this, a three-layered framework to quantify and assess the circularity potential (Ω) of RA has been developed. To give stakeholders and legislative bodies a simple method to assess the opportunities available to them to become “more circular”, a novel equation has been formulated. This takes the form of a three-level indicator that considers: technical aspects, the effect of the RA market, and the legislative restrictions. A case study in Germany was structured and undertaken to develop and verify the proposed approach. The results indicate that the available RA is insufficient to cover the needs of asphalt mixture production; even though RA production is significantly lower than the actual need of asphalt mixtures, it is not utilized in its entirety. An impactful step forward is the alteration of the regulations to support the higher utilization of RA in asphalt mixtures, and subsequently, the increased circular opportunity and potential of RA. Thus, Circularity potential (Ω) is a composite indicator that can support stakeholders, designers, and asset managers during the process of decision-making, to follow more circular operational, design, and asphalt pavement management patterns

ISIM - INFRASTRUCTURES & STRUCTURES INFORMATION MODELING: A NEW CONCEPT OF BIM FOR INFRASTRUCTURES

The application of Building Information Modeling (BIM) in infrastructure and structural projects, known as Integrated Structural and Infrastructure Modeling (ISIM), has gained attention in recent years due to its potential to revolutionize the construction industry. By providing a digital representation of the built environment, BIM allows for improved collaboration and communication between project stakeholders, leading to enhanced project outcomes. The ISIM approach is centered on the creation of a digital twin, a three-dimensional model of the infrastructure or structure, which serves as a virtual replica of the physical asset. This digital twin provides a platform for analysis, decision-making, and management throughout the project lifecycle, from design and construction to operation and maintenance. One of the key benefits of the ISIM approach is the ability to optimize the construction process, reducing costs, and improving efficiency. The digital twin allows for the identification of potential issues in the design phase, enabling them to be addressed before construction begins. The model can also be used to simulate different scenarios, providing insights into the most effective construction methods, sequencing, and scheduling. Additionally, the use of ISIM can facilitate collaboration and communication among project stakeholders, including architects, engineers, contractors, and owners. The digital twin provides a shared platform for all stakeholders to access and contribute to, allowing for real-time feedback and decision-making. This increased collaboration can lead to reduced errors, improved quality, and enhanced project outcomes. In this paper the authors propose the example of the Meier bridge in Alessandria starting from the 2D drawings to create the 3D model and link it to the external context using Autodesk Infraworks software. A virtual reality implementation has been considered as useful tool to improve the maintenance management

UN APPROCCIO BASATO SULLA MODELLAZIONE 3D E IL LIFE CYCLE ASSESSMENT PER UNA GESTIONE SOSTENIBILE DELLA MANUTENZIONE STRADALE

Among several goals of the road agencies, one of the most relevant is the maintenance and rehabilitation of the road pavement. The growth of traffic, the longstanding lack of funding and, sometimes, an emergency-based planning of intervention, are common drivers leading to low level of pavement conditions in terms of ride quality and safety. In addition both cost and environmental concerns due to monitoring stage are relevant issues within the management system of local and urban road network, especially. With the purpose of implementing  sustainability in the road pavement  management, this paper provides an approach based on coupled low- cost 3D image modelling distress identification and  Life Cycle Assessment (LCA) tool. A case study in Palermo is considered by comparing current practices to the optimized system to define environmental impacts. The results show the use of this approach is able to achieve both environmental and economic benefits for road agencies by providing crucial savings and furthermore by optimising the Pavement Management System