http://repositorio.lnec.pt:8080/jspui/handle/123456789/37 2026-04-04T21:00:40Z 2026-04-04T21:00:40Z Silveira, A. P. C. da Baptista, A. M. Azevedo, F.S. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017261 2024-05-29T14:52:01Z 1991-01-01T00:00:00Z

Contributions à la conception des témoins sonores utilisés dans les structures de béton précontraint Silveira, A. P. C. da; Baptista, A. M.; Azevedo, F.S. Le propos de cette communication est la présentation des critères de conception des témoins sonores, de façon qu'ils puissent mesurer correctement les déformations et permettent d'évaluer indirectement les contraintes du béton. Ces critères essaient de fixer le champ de mesure et la raideur convenables à la mesure des déformations. On présentera des résultats expérimentaux et une simulation par ordinateur du comportement des témoins sonores installés au sein du béton.

1991-01-01T00:00:00Z Cintura, E. Lina Nunes Molari, L. Bettuzzi, M. Morigi, M. Brancaccio, R. Faria, P. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017250 2024-05-29T14:51:46Z 2024-01-19T00:00:00Z

Hygroscopicity and Morphology of Bio-Based Boards—The Infuence of the Formulation Cintura, E.; Lina Nunes; Molari, L.; Bettuzzi, M.; Morigi, M.; Brancaccio, R.; Faria, P. Takayoshi Kobayashi The internal structures and the hygroscopicity of bio-based boards consisting of giant reed (Arundo donax L.) and hazelnut shells as bio-aggregates, and a sodium silicate solution as the adhesive, were investigated. The aim was to evaluate the influence of each material (the bio-aggregates and adhesive) and their distributions in the boards on the final performance. By carrying out X-ray computed tomography, the internal structures and the porosities of the boards were determined, allowing important considerations of their hygroscopicity. The voids’ percentages were between 26% and 36% of the total volume of the composites. Both the materials and the composites demonstrated high hygroscopicity. In particular, the mixtures of the bio-aggregates and the sodium silicate allowed reaching a moisture buffering value of 7.44 g/(m2%RH) for the A. donax-based composite, 3.86 g/(m2%RH) for the hazelnut-shell-based composite, and 4.65 g/(m2%RH) for the mixture-based composite. Besides the identification of the contributions of the materials, a detailed discussion of the assessed properties was carried out to use these bio-based boards in vernacular historic construction. The results show how the aggregate type and the adhesive content affected the final behavior, demonstrating the importance of a conscious material choice. Furthermore, helpful information for the future development of these types of bio-based boards and their possible optimization was provided.

2024-01-19T00:00:00Z Fernandes, R. Ferreira, N. Lopes, S. Santos, J. Pereira, N. Ferreira, N. Lina Nunes Martins, J. Carvalho, L. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017249 2024-05-29T14:51:41Z 2023-12-31T00:00:00Z

Development of an Innovative Lightweight Composite Material with Thermal Insulation Properties Based on Cardoon and Polyurethane Fernandes, R.; Ferreira, N.; Lopes, S.; Santos, J.; Pereira, N.; Ferreira, N.; Lina Nunes; Martins, J.; Carvalho, L. Bo-Tao Huang; Janny Chen The search for innovative and sustainable solutions to improve the energy efficiency of the construction industry has been a hot topic for researchers due to the tremendous impact of insulator materials in the thermal comfort of buildings. In the present work, an innovative lightweight composite material with thermal insulation properties was developed, for the first time, by using cardoon particles and polyurethane. The formulation of the composite material was optimized in terms of cardoon fraction and the polyol/isocyanate ratio, to achieve the best compromise between internal bond (IB) strength and thickness swelling (TS). The best performing composite was PU75-CP45, with 45 wt% of cardoon particles and 75% of isocyanate, achieving an IB of 0.41 MPa and a TS of 5.3%. Regarding insulation properties, the PU75-CP45 composite material exhibits a promising performance when compared to conventional construction industry materials by tuning its thickness. Additionally, the composite material presented very low emissions of volatile organic compounds and formaldehyde (bellow to legislation levels) and high resistance to biological degradation

2023-12-31T00:00:00Z Duarte, S. Magro, A. Barros, G. Carvalho, M. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017248 2024-05-29T15:08:44Z 2024-01-10T00:00:00Z

Stored products insects in Portugal – New data and overview Duarte, S.; Magro, A.; Barros, G.; Carvalho, M. C. G. Athanassiou; Carvalho Guedes; Z. Lu; M. K. Nayak The introduction of stored product insect pests to new areas is facilitated by food trade among countries, and effective detection and monitoring programs are crucial for food security. The khapra beetle, Trogoderma granarium Everts is one of the most destructive insect species. In Portugal, T. granarium has been detected in 1988. However, no new data has been added to this information since that date. Floor traps with pheromones specific to T. granarium were used and placed inside ports, mills, and storage facilities, including warehouses and silos, between June and September in 2017, 2019, 2021, and 2022.Previous results from other sampling programs conducted between 2002 and 2008 are also referred here to add more evidence for the presence or absence of T. granarium in Portugal. Here, various types of traps, including some generalists and others with pheromones (such as T. granarium), were used. The collected insects were identified to species, or genus.Surveys conducted identified approximately 40 insect species that are associated with stored products, in a total of 23.725 insects, and among them, the weevils belonging to the genus Sitophilus C.J.Schoenherr have been recognized as the main pests that affects stored cereals. Regarding the surveys made between 2017 and 2022 and previous surveys done in Portugal (between 2002 and 2008; n = 26.719 insects identified), no T. granarium individuals were detected in any of the entomological samples, and only a few Dermestidae specimens were found across all surveys, one of them belonging to the same genus, identified as Trogoderma inclusum LeConte. With the predicted changes in climate, there is a risk of introducing T. granarium and other destructive insect pests that could displace itophilus weevils as the key stored products pest in Portugal. Therefore, it is crucial to monitor and implement measures to prevent the spread of invasive pests for effective pest management and food security purposes, using proper trapping methods and accurate and rapid identification tools.

2024-01-10T00:00:00Z