http://repositorio.lnec.pt:8080/jspui/handle/123456789/59 Wed, 13 May 2026 16:15:59 GMT 2026-05-13T16:15:59Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019503 Title: Effect of the geometrical and physical nature of filler on the rheological properties of mastics Authors: Antunes, Vítor; Freire, A. C.; Sheidaei, M.; Östlund, J. Abstract: This study investigates properties of mastics produced with 70/100 neat bitumen, three mineral fillers (granite, quartz-granite, and diorite), and a lime-based active filler at filler- to-bitumen (F/B) ratios of 40%, 50%, and 60%. The physical, geometrical, and mineral- ogical properties of the fillers were assessed. Their influence on mastics' behaviour was evaluated using conventional penetration and softening point tests, as well as fre- quency sweep tests at different temperatures with a dynamic shear rheometer (DSR). Although mineral components are not strongly correlated with mastic behaviour, differences in particle size distribution and rigid void (RV) properties explain the varying stiffening effects. Granite, with finer particles, had the least rut resistance, while diorite, with coarser particles, had the greatest resistance at F/B values of 40% and 60%. Quartz- granite exhibited the highest F/B ratio dependency and strongest interaction with bitumen at 50% F/B at lower temperatures, highlighting the importance of selecting the appropriate filler proportion over the filler type when the features are similar. The study underscores necessity of using DSR to assess mastics with diverse fillers across various conditions. Therefore, two equations to estimate the complex modulus |G*| from standardised softening point test and RV normalised with F/B ratio are proposed, which require further research. Tue, 11 Nov 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019503 2025-11-11T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019499 Title: Potential Use of Brewer’s Spent Grain By-Product as a Component for Sustainable Thermal Mortars Authors: Manso, M.; Silva, J.; Antunes, Vítor; Ivo, I.; Canto, J.; Guerra, C. Abstract: Buildings represent approximately 40% of the total energy consumption. Net-zero energy buildings (NZEBs) have lower energy demands than conventional buildings due to improved thermal insulation combined with other passive design strategies. Thermal mortars, used in insulating plasters, help improve buildings’ energy efficiency in a cost-effective manner, with minimal added thickness, even on irregular surfaces. Brewer’s spent grain (BSG) accounts for 85% of the total by-products of the brewing industry. It is a cellulosic wood material, with a composition rich in protein (20%) and fiber (70%). Considering these properties, it has potential for use as a natural aggregate in mortars and as a sustainable material for buildings aligned with circular economy principles. This work aims to characterize BSG as a natural by-product for use in thermal mortars and identify different incorporation percentages. First, BSG was characterized in terms of its water content, particle size and volume mass. Then, mortars with BSG and fine sand, with different water contents, were produced and compared to a reference mortar and two commercially available thermal mortars. The performance of the mixtures was evaluated in terms of water absorption, mechanical behavior (namely, compressive and flexural strength) and thermal behavior. BSG mortars with a 0.25 w/c ratio presented a water absorption coefficient similar to that of the reference mortar. Overall, BSG mortars presented a mechanical strength profile similar to that of conventional thermal mortars. In the thermal test, the best BSG mortar (BSG75-w/c-0.25) achieved a stationary temperature difference between surfaces that was 8% lower than that of a commercial thermal mortar and 110% higher than that of the reference mortar. In sum, the best BSG mortars had a lower w/c ratio. Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019499 2025-01-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019498 Title: Self-Healing Asphalt Mixtures Meso-Modelling: Impact of Capsule Content on Stiffness and Tensile Strength Authors: Câmara, G.; Azevedo, N.; Micaelo, R. Abstract: 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/123456789/1019498 2025-01-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019495 Title: Modelling the influence of capsules on the behaviour of asphalt mixtures Authors: Câmara, G.; Micaelo, R.; Azevedo, N. Abstract: Over the years, different methodologies, such as encapsulated rejuvenators, have been investigated to extend the service life of roads. However, these elements may impact the mechanical performance of asphalt mixtures, and accurately assessing their effects through experimental methods remains challenging, especially when isolating their influence from rejuvenator release. This study adopts the VirtualPM3DLab discrete-based model to evaluate the effect of capsules on the stiffness behaviour and tensile strength of asphalt mixtures. Mixtures incorporating different capsule contents (0.30 and 0.75 wt.%) were subjected to dynamic tension-compression and monotonic tensile tests. The results show that the impact on the stiffness modulus progressively increases with capsule content, reaching reductions between 4.3% and 8.7%, while the phase angle remains unaffected. Regarding tensile strength, the presence of capsules has a limited influence on the peak stress, which decreases from 3.80 MPa to 3.74 MPa (1.6%) and 3.57 MPa (6.1%) for the respective capsule ratios. The overall post-peak predictions across all scenarios follow a similar trend. In all scenarios, the majority of broken contacts are concentrated in the notch tip zone, consistent with experimental results reported for these materials. Broken contacts associated with capsules are mostly located in this region, which may facilitate the self-healing process once rejuvenator release is included in future simulations. The evaluated contents can, therefore, be safely adopted without significantly compromising the overall performance of asphalt mixtures. Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019495 2025-01-01T00:00:00Z