http://repositorio.lnec.pt:8080/jspui/handle/123456789/1007791 Mon, 26 Oct 2026 10:07:43 GMT 2026-10-26T10:07:43Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019997 Effect of aggregate shape representation and deformability on the bituminous mixture stiffness properties using 3D DEM modelling Micaelo, R.; Azevedo, N.; Câmara, G. Given the recognised importance of aggregate shape in the performance of bituminous mixtures, there has been growing interest in developing numerical models that accurately capture the material’s mesostructural characteristics. This paper presents a methodology for incorporating complex aggregate shapes into three-dimensional (3D) Discrete Element Method (DEM) models of bituminous materials and investigates the impact of representing coarse aggregates as deformable bodies on both the geometry and mechanical response of DEM assemblies. This approach was implemented in VirtualPM3DLab, a 3D DEM software that employs Laguerre–Voronoi diagrams to define spherical particle contacts and contact areas, together with a generalised Kelvin contact model to simulate the viscoelastic behaviour of bituminous materials. The mechanical response of DEM assemblies, using rigid single-spherical particle aggregates versus deformable multi-spherical particle aggregates, was analysed through simulated uniaxial tension–compression cyclic tests at various frequencies. The results show that discretising the aggregate volume using a distribution of smaller-radius spherical particles effectively captures aggregate geometry, although the sphere size distribution must be carefully selected to ensure high-fidelity representation. Virtual asphalt specimens with deformable multisphere aggregate particles exhibited higher stiffness moduli and lower phase angles across the tested frequencies compared to rigid single-sphere specimens. These variations in viscoelastic properties were more pronounced with finer aggregate discretisation, due to the increased number of aggregate–aggregate and aggregate–mastic contacts. In contrast, the total number of contacts and their distribution among constituents were very similar for assemblies with irregular particle models (realistic) and subdivided icosahedron models (close to spherical), resulting in a minimal effect of aggregate shape on the overall DEM simulation results. Thu, 09 Apr 2026 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019997 2026-04-09T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019609 Unveiling emerging communities: a network approach on transport decarbonisation technology Aparício, J.; Arsénio, E.; Henriques, R. What are the latent thematic communities driving transport decarbonisation research across road, rail, maritime, and crossmodal domains? To answer this central question, this work proposes an integrated network model that fuses bibliographic coupling with Sentence-BERT semantic similarities, followed by a statistical analysis using state-of-the-art community detection algorithms. We assess partitions via four complementary metrics, modularity, silhouette, density, and NF1, and compare weighted versus unweighted graphs. Our analysis of mode-specific corpora uncovers distinct clusters: road research splits into urban last-mile automation and rural logistics; rail coalesces around a synchromodal scheduling hub with biofuel and corridor electrification offshoots; maritime divides into green fuels, autonomous safety, and shore-power streams; and crossmodal studies form overlapping triads of electrification, data analytics, and blockchain. Weighted edge integration uniformly enhances thematic clarity without altering algorithm rankings. These findings yield actionable algorithm-selection heuristics and tie each community to specific SDG targets, transforming aspirational goals into a concrete, community-by-community policy roadmap for green logistics. Sat, 17 Jan 2026 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019609 2026-01-17T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019493 Modelação numérica discreta de materiais com o VIRTUALPM3DLAB Câmara, G.; Azevedo, N.; Micaelo, R. Os modelos baseados no Método dos Elementos Discretos (MED) são eficazes na modelação de materiais com estrutura granular, como as misturas betuminosas. Esta comunicação descreve o desenvolvimento do VirtualPM3DLab, um laboratório virtual tridimensional baseado no MED, projetado para simular materiais complexos, incluindo as misturas betuminosas autorreparáveis. O VirtualPM3DLab permite a representação detalhada da mesoestrutura irregular e dos contactos partícula-partícula, possibilitando a análise do comportamento mecânico, da evolução do dano e da reparação/autorreparação em pavimentos. O software incorpora modelos de contacto viscoelásticos e modelos de dano associados, permitindo a avaliação das propriedades viscoelásticas, resistência mecânica e comportamento pós-reparação das misturas. Para garantir a precisão, foram acoplados uma ferramenta de calibração macroscópica e um módulo de visualização para pré e pós-processamento. A calibração e validação do VirtualPM3DLab foram realizadas para diferentes materiais betuminosos e condições de carregamento, com boa correlação entre os resultados numéricos e experimentais. O software tem sido particularmente útil na análise de misturas betuminosas autorreparáveis com agentes encapsulados, sendo aplicado na simulação de diferentes cenários de carregamento. O trabalho estabelece uma base sólida para uma abordagem numérica eficiente na modelação da mesoestrutura 3D de materiais complexos, abrindo caminho para o desenvolvimento de pavimentos mais eficientes e sustentáveis. Futuramente, o módulo VirtualPM3DLab poderá ser incorporado em sistemas de gestão rodoviária baseados em modelos digitais. Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019493 2025-01-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019491 Self-Healing Asphalt Mixtures Meso-Modelling: Impact of Capsule Content on Stiffness and Tensile Strength Câmara, G.; Azevedo, N.; Micaelo, R. Capsule-based self-healing technologies offer a promising solution to extend pavement service life without requiring external activation. The effect of the capsule content on the mechanical behaviour of self-healing asphalt mixtures still needs to be understood. This study presents a numerical evaluation of the isolated effect of incorporating capsules containing encapsulated rejuvenators, at different volume contents, on the stiffness and strength of asphalt mixtures through a three-dimensional discrete-based programme (VirtualPM3DLab), which has been shown to predict well the experimental behaviour of asphalt mixtures. Uniaxial tension–compression cyclic and monotonic tensile tests on notched specimens are carried out for three capsule contents commonly adopted in experimental investigations (0.30, 0.75, and 1.25 wt.%). The results show that the effect on the stiffness modulus progressively increases as the capsule content grows in the asphalt mixture, with a reduction ranging from 4.3% to 12.3%. At the same time, the phase angle is marginally affected. The capsule continuum equivalent Young’s modulus has minimum influence on the overall rheological response, suggesting that the most critical parameter affecting asphalt mixture stiffness is the capsule content. Finally, while the peak tensile strength shows a maximum reduction of 12.4% at the highest capsule content, the stress–strain behaviour and damage evolution of the specimens remain largely unaffected. Most damaged contacts, which mainly include aggregate–mastic and mastic–mastic contacts, are highly localised around the notch tips. Contacts involving capsules remained intact during early and intermediate loading stages and only fractured during the final damage stage, suggesting a delayed activation consistent with the design of healing systems. The findings suggest that capsules within the studied contents may have a moderate impact on the mechanical properties of asphalt mixtures, especially for high-volume contents. For this reason, contents higher than 0.75 wt.% should be applied with caution. Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019491 2025-01-01T00:00:00Z