Periodic Reporting for period 1 - AMRAB (Adhesion Multiphysics of Rubberised Asphalt Binders)
Reporting period: 2021-10-01 to 2023-09-30
Asphalt pavements play a vital role in the European and global transport infrastructure industry as they drive economic growth and social well-being in all countries. Public investment in road construction in Europe totals about €80 billion per year. In Europe, it is estimated that over 90% of the 5.2 million km of paved roads and highways are surfaced with asphalt. Europe has about 4,000 asphalt production plants and produces 435 million metric tonnes per year. Meanwhile, with the increased number of vehicles, approximately one billion end-of-life tires (ELTs) are produced every year. The rising environmental awareness has driven people to seek appropriate treatment and disposal of ELTs, such as retreading, energy recovery and material recycling. In civil engineering, bitumen modification with crumb rubber from ELTs has been successfully applied in the paving industry because of its economic and environmental benefits. The rubberised asphalt concrete technology not only increases the disposal of ELTs but also improves the overall performance of asphalt pavements with added values, e.g. noise reduction, higher skid resistance, etc. Field and laboratory tests have demonstrated that rubberised asphalt mixtures have greater resistance to fatigue/thermal cracking and rutting. However, significant concerns exist around the aging and moisture-induced durability damages (e.g. block cracks and potholes) of rubberised asphalt that impede its further applications, which fundamentally results from the weak adhesion between the CRMB and the rock aggregates under severe environmental (moisture and ageing) conditions. In response to the European objective of sustainable development, this specific project aims to develop a durable CRMB technology with a high adhesion performance to reduce the consumption of raw materials (e.g. petroleum bitumen), increase recycling of ELTs while still meeting the demand for long-term durability and improved pavement performance.
AMRAB accepts all scientific challenges and the overall Research Objective (RO) is to train the Fellow through this interdisciplinary project focused on modelling the adhesion multiphysics of CRMB and developing adhesion promoters and technologies for industrial applications. Specifically,
RO1: Training of the Fellow’s academic expertise, professional skills and inter-sectoral collaboration.
RO2: Fundamental investigation of adhesion multi-physical mechanisms of CRMB at field environmental conditions.
RO3: Modelling the circular dependences of adhesion multiphysics and computational performance prediction of CRMB.
RO4: Experimental development and evaluation of materials and technologies to improve adhesion between CRMB and aggregates.
RO5: Industrial application of adhesion evaluation framework and adhesion promoters in rubberised asphalt pavements.
AMRAB accepts all scientific challenges and the overall Research Objective (RO) is to train the Fellow through this interdisciplinary project focused on modelling the adhesion multiphysics of CRMB and developing adhesion promoters and technologies for industrial applications. Specifically,
RO1: Training of the Fellow’s academic expertise, professional skills and inter-sectoral collaboration.
RO2: Fundamental investigation of adhesion multi-physical mechanisms of CRMB at field environmental conditions.
RO3: Modelling the circular dependences of adhesion multiphysics and computational performance prediction of CRMB.
RO4: Experimental development and evaluation of materials and technologies to improve adhesion between CRMB and aggregates.
RO5: Industrial application of adhesion evaluation framework and adhesion promoters in rubberised asphalt pavements.
Extensive training activities were taken by the Fellow to enhance his expertise in theoretical material science and chemistry knowledge, multiphysics computational modelling and performance predictions, experimental material characterisation, and model implementation in industrial applications. In addition, project management, communication and networking skills were also developed via the project. Knowledge inter-transfer was also stimulated between the Fellow and the hosts. The main research activities and results achieved so far include:
• Multiphysics adhesion mechanisms of rubberised asphalt binders. The models for interrelated multiphysics adhesion mechanism contain 1) environmental physics; 2) chemical models for rubber swelling and dissolution, adhesion initiation; 3) mechanics-based constitutive modelling; and 4) microstructural morphology.
• Prediction model of adhesion multiphysics for rubberised asphalt binders. Circular dependencies between the Multiphysics of adhesion were identified and coupled with each other through material fundamental properties (e.g. surface energy, bond energy, diffusivity, modulus) and shared parameters and variables in the constitutive models. A systematic adhesion model was formed by assembling all separate models to interpret the fundamental adhesion mechanisms at the CRMB-aggregate interface.
• Experimental development and evaluation of the adhesion performance. Selective bitumen, aggregates and adhesion promoters were tested in the laboratory and examined using the proposed adhesion models and computational framework (Molecular dynamics simulations). Mechanical testing including dynamic shear rheometer (DSR) at varying testing conditions, surface free energy (SFE) measurements and bitumen bond strength (BBS) tests were performed to quantitatively evaluate the adhesive bond between CRMB and aggregate. Based on experimental and numerical results, an optimized evaluation protocol considering both materials design and service conditions was proposed to evaluate the effectiveness of the existing or newly developed adhesion promoters and technologies.
• Industry applications and feedback. The adhesive performance of industry bituminous binders at Total and industry asphalts at AI were evaluated using the proposed adhesion models and the developed computational performance prediction framework. New anti-stripping materials and technologies were potentially identified for industry use. Construction technologies and design practices were optimized based on the feedback from the industrial applications to increase the adhesion capacity and strength of CRMB.
The results of the project were disseminated and published to the most extent via multiple communication platforms such as printed publications (3 journal articles), 4 conference presentations, 2 workshops, 2 seminars and so on, which targeted a variety of potential users and partners including material companies, infrastructural designers, engineers, managers, contractors, and researchers throughout Europe and the world.
• Multiphysics adhesion mechanisms of rubberised asphalt binders. The models for interrelated multiphysics adhesion mechanism contain 1) environmental physics; 2) chemical models for rubber swelling and dissolution, adhesion initiation; 3) mechanics-based constitutive modelling; and 4) microstructural morphology.
• Prediction model of adhesion multiphysics for rubberised asphalt binders. Circular dependencies between the Multiphysics of adhesion were identified and coupled with each other through material fundamental properties (e.g. surface energy, bond energy, diffusivity, modulus) and shared parameters and variables in the constitutive models. A systematic adhesion model was formed by assembling all separate models to interpret the fundamental adhesion mechanisms at the CRMB-aggregate interface.
• Experimental development and evaluation of the adhesion performance. Selective bitumen, aggregates and adhesion promoters were tested in the laboratory and examined using the proposed adhesion models and computational framework (Molecular dynamics simulations). Mechanical testing including dynamic shear rheometer (DSR) at varying testing conditions, surface free energy (SFE) measurements and bitumen bond strength (BBS) tests were performed to quantitatively evaluate the adhesive bond between CRMB and aggregate. Based on experimental and numerical results, an optimized evaluation protocol considering both materials design and service conditions was proposed to evaluate the effectiveness of the existing or newly developed adhesion promoters and technologies.
• Industry applications and feedback. The adhesive performance of industry bituminous binders at Total and industry asphalts at AI were evaluated using the proposed adhesion models and the developed computational performance prediction framework. New anti-stripping materials and technologies were potentially identified for industry use. Construction technologies and design practices were optimized based on the feedback from the industrial applications to increase the adhesion capacity and strength of CRMB.
The results of the project were disseminated and published to the most extent via multiple communication platforms such as printed publications (3 journal articles), 4 conference presentations, 2 workshops, 2 seminars and so on, which targeted a variety of potential users and partners including material companies, infrastructural designers, engineers, managers, contractors, and researchers throughout Europe and the world.
The main innovation activities of this project include:
• A fundamental understanding of the adhesion mechanism by involving the circular dependences of the adhesion-relevant Multiphysics for rubberised asphalt binders.
• A unique molecular dynamics simulation and prediction framework for the adhesion of rubberised asphalt binders.
• A comprehensive evaluation protocol considering both materials design and service conditions developed to effectively screen and evaluate the interfacial adhesion performances of rubberised asphalt binders.
• An innovative development of new sustainable adhesion promoters and technologies used in rubberised asphalt binders for industrial applications.
These new materials and methods are expected to extend the roads’ service life. Being able to produce more durable and sustainable transport infrastructure through enabling material circularity aligns with the UK’s Industrial Strategy by addressing the Grand Challenge in “Future of Mobility”. It is also obviously contributing to the EU’s commitment to Net Zero. The adhesion performance framework was introduced through workshops and seminars with the researchers in host/co-hosts and research collaborators for evaluation and implementation. The innovative adhesive materials evaluation protocol was shared via seminars with industry users such as material companies and construction contractors for testing and assessing the materials.
• A fundamental understanding of the adhesion mechanism by involving the circular dependences of the adhesion-relevant Multiphysics for rubberised asphalt binders.
• A unique molecular dynamics simulation and prediction framework for the adhesion of rubberised asphalt binders.
• A comprehensive evaluation protocol considering both materials design and service conditions developed to effectively screen and evaluate the interfacial adhesion performances of rubberised asphalt binders.
• An innovative development of new sustainable adhesion promoters and technologies used in rubberised asphalt binders for industrial applications.
These new materials and methods are expected to extend the roads’ service life. Being able to produce more durable and sustainable transport infrastructure through enabling material circularity aligns with the UK’s Industrial Strategy by addressing the Grand Challenge in “Future of Mobility”. It is also obviously contributing to the EU’s commitment to Net Zero. The adhesion performance framework was introduced through workshops and seminars with the researchers in host/co-hosts and research collaborators for evaluation and implementation. The innovative adhesive materials evaluation protocol was shared via seminars with industry users such as material companies and construction contractors for testing and assessing the materials.