The construction and maintenance of road infrastructures and buildings are evolving in response to environmental demands and the need for more efficient, durable and cost-effective materials. Current research focuses on advanced road materials—such as bituminous composites, recycling agent, natural or recycled geosynthetics, bio-based polymers, and reactive binders—that must meet both high performance and environmental standards, including carbon neutrality and pollutants in situ degradation. Similarly, the development of sustainable building materials made with plant-based aggregates as bio-based concrete or natural fibers as natural fibers reinforced composites must meet comparable durability and environmental requirements. Significant progresses have been made in developing new molecular compounds, including bio-sourced polymers, functionalized lignin, and modified bitumen with functional additives. These new generation advanced materials are engineered for properties like optimal viscoelasticity, self-healing, and improved adhesion. Nevertheless, several challenges remain, at several levels: microscopic, mesoscopic and macroscopic.

In addition to experimental and implementation-related challenges, a central focus is the multiscale modeling of these materials, which must account for phenomena ranging from molecular interactions (e.g., polymer entanglement, additive diffusion, interfacial bonding) up to the macroscopic behavior of the road layers under traffic and climate and of buildings under environmental conditions. The change of scale remains however, not fully understood. [1] Indeed, the properties of interest—viscoelastic behavior, binding adhesion, phase compatibility, microstructure evolution under aging—are strongly scale-dependent and require sophisticated computational approaches and further developments and implementations. For instance, molecular dynamics (MD) simulations, coarse-grained modeling, and mesoscopic phase field methods are increasingly used to bridge the gap between formulation and material performance. [2] These are often coupled with continuum mechanics models (e.g., finite element analysis, poromechanics) that predict large-scale deformation, cracking, or rutting in road pavements as well as the mechanical and thermal behavior of bio-based building materials.

At the same time, experimental characterization techniques—including microscopy (SEM, AFM), spectroscopic methods (FTIR), chromatography (GPC), calorimetry (DSC), rheological testing, microtomography (CT), and environmental simulation chambers—provide essential data to validate models and calibrate parameters. The interplay between modeling and characterization is thus at the heart of current research, especially in the context of low-carbon infrastructure and building development.

The main challenges to the study of road materials arise from their complexity and the multi-physics, multi-scale nature of their degradation phenomena.

These include for instance:

·        The description of the microstructure and micro-properties of asphalt and biobased materials at the microscopic level must rely on molecular dynamics (MD) simulations using tailored force fields, derived either from empirical data or advanced quantum mechanical calculations.

·        Bitumen,asphalt, bio-based concrete, composite are complex multiphase composites whose heterogeneous phases interact unpredictably at the microscale, with interfaces, such as bitumen–aggregate, bio-based aggregates-binders filler–matrix, posing significant challenges for accurate characterization and simulation.

·        The computational complexity of these systems. This requires balancing model fidelity with computational efficiency to make simulations practical for design and material optimization.

·        A key modeling goal is to predict macroscopic properties, such as fatigue life and cracking resistance, from microstructural features and aging mechanisms, which requires approaches like homogenization, multi-scale coupling, or machine learning, each with inherent limitations.

·        The lack of high-resolution experimental data, calibrating and validating micro/meso-scale models.

For these reasons, there is an urgent need to develop and implement new, generalizable methodologies that can bridge scales and accurately capture the chemical and mechanical aging of these materials. Therefore, the main aim of this CECAM workshop is to bring together early-career, established, and senior researchers, both academic and industrial, to share their expertise and present state-of-the-art approaches in the modeling and characterization of road and building materials, from molecular simulations to mesoscopic and continuum descriptions. We will target also the main bottlenecks that could hinder advances in this filed and the industrial large-scale setting.