DSpace Community: DMDMhttp://repositorio.lnec.pt:8080/jspui/handle/123456789/292026-05-11T18:46:13Z2026-05-11T18:46:13ZIPaintS - Intelligent Coatings for Concrete Structures: immobilization of pH indicators on coating membranesCristino, A.Lopreto, J.Silva, H. M.Santos Silva, A.Rodrigues, M. P.Cabral-Fonseca, S.Ferreira, O.Nunes, J.Soeira, B.Galhano, R.http://repositorio.lnec.pt:8080/jspui/handle/123456789/10195232026-05-05T16:31:42Z2025-06-13T00:00:00ZTitle: IPaintS - Intelligent Coatings for Concrete Structures: immobilization of pH indicators on coating membranes
Authors: Cristino, A.; Lopreto, J.; Silva, H. M.; Santos Silva, A.; Rodrigues, M. P.; Cabral-Fonseca, S.; Ferreira, O.; Nunes, J.; Soeira, B.; Galhano, R.
Editors: Grantham, M.; Custódio, J.; Real, S.
Abstract: In Portugal and over the world, a significant number of concrete structures face challenges due to expansive chemical reactions, such as the alkali-silica reaction (ASR). These reactions have been shown to cause various types of damage, with microcracking being the most common, resulting from internal stresses created by the expansion of reaction products. It is well-documented that, over time, these microcracks can develop into significant fissures due to the hygroscopic nature of these products, which accelerates concrete degradation and potentially compromises structural integrity. One key aspect of ASR products is the presence of alkaline hydroxides in the gel formation process, resulting in elevated pH levels. When this gel reaches the concrete carbonated surface, a change in pH occurs. Based on this premises, the project IPaintS was undertaken to develop a coating that could detect the formation of ASR products on concrete surfaces by identifying variations in pH. This paper presents the results of the preliminary tests conducted, specifically the tests performed to confirm the possibility of immobilising pH indicators in a coating membrane and assess performance characteristics of the functionalised coating. Results show the effective immobilization of a pH indicator on a coating membrane without the loss of some fundamental properties of both the indicator and the coating membrane.2025-06-13T00:00:00ZMissing data estimation method for durability survey of reinforced concrete structuresRincon, L.Habeeb, B.Eustaquio, E.Hamami, A.Matos, J.Moscoso, Y.Bastidas-Arteaga, E.http://repositorio.lnec.pt:8080/jspui/handle/123456789/10193952026-05-05T15:09:24Z2025-01-16T00:00:00ZTitle: Missing data estimation method for durability survey of reinforced concrete structures
Authors: Rincon, L.; Habeeb, B.; Eustaquio, E.; Hamami, A.; Matos, J.; Moscoso, Y.; Bastidas-Arteaga, E.
Abstract: Reinforced concrete (RC) structures are well-known for their high durability; however, they remain vulnerable to natural hazards and extreme events that can impact their performance over time. In aggressive environments, there is a high likelihood of increased maintenance, rehabilitation, and repair actions that constitute a significant portion of the total lifecycle spending. Monitoring systems have been implemented during the last decades to collect periodically or continuously essential data about the durability performance of the structures in real operation. However, the effectiveness of these systems is impacted by sensor efficacy, influenced in turn by environmental factors, sensor durability, and power outages, leading to intermittent or permanent data gaps. This study proposes a methodology to address the problem of missing data of a Structural Health Monitoring (SHM) system, specifically aiming to provide more accurate and continuous information from concrete resistivity and temperature sensors to support the early detection of corrosion. The proposed methodology was applied to a repaired RC structure with over fourteen years of data, where significant gaps in the measurements were present. The approach combines several techniques to fill these gaps: deep machine learning for air temperature, generalized linear models for concrete temperature, and pattern recognition for concrete resistivity. To the best of the authors’ knowledge, this is the first time a methodology has been proposed for imputing missing data from resistivity sensors in SHM systems, which are increasingly being implemented. This approach is innovative and offers potential benefits for SHM system managers, providing more information on long-term sensor data that could aid in early corrosion detection and maintenance planning. The application of the proposed methodology to a real case study indicated a successful imputation of 43.4% of missing data although some challenges persist for sensors located in areas characterized by high measurements variability.2025-01-16T00:00:00ZMateriais de construção produzidos e usados em Portugal que podem suscitar preocupação do ponto de vista da proteção radiológicaTrindade, M.Malta, M.Fonseca, H.Santos Silva, A.Costa, D.Batista, F.Pereira, A.Dinis, M.http://repositorio.lnec.pt:8080/jspui/handle/123456789/10193402026-05-05T16:22:45Z2025-04-01T00:00:00ZTitle: Materiais de construção produzidos e usados em Portugal que podem suscitar preocupação do ponto de vista da proteção radiológica
Authors: Trindade, M.; Malta, M.; Fonseca, H.; Santos Silva, A.; Costa, D.; Batista, F.; Pereira, A.; Dinis, M.
Abstract: Na construção civil, é comum a utilização de materiais geológicos,
seja diretamente ou incorporados nos materiais de construção. A presença
de radionuclídeos naturais nesses materiais pode resultar em exposição à
radiação ionizante, seja por meio da exposição externa à radiação gama ou
pela inalação do gás radão. A Agência Portuguesa do Ambiente estabelece
medidas adequadas para controlar os materiais de construção, visando proteger
a população contra radiações ionizantes no interior dos edifícios. Um
estudo foi conduzido com o objetivo de identificar os materiais de construção
produzidos e utilizados em Portugal que possam gerar preocupações radiológicas,
com especial ênfase na radiação gama. Neste trabalho, apresentam-se
os resultados relativos ao índice de concentração de atividade (I), relacionado
com a dose de radiação gama proveniente dos materiais de construção, permitindo
rastrear os materiais que podem fazer com que o nível de referência
de dose seja excedido. O estudo destaca maior preocupação radiológica
em relação aos granitos e pozolana natural, bem como alguns subprodutos
e produtos industriais, como cinzas volantes, argila expandida, betão com
agregado granítico e determinados pavimentos e revestimentos cerâmicos.2025-04-01T00:00:00ZHYGROTHERMAL DURABILITY OF VACUUM INFUSED GFRP COMPOSITES PRODUCED WITH POLYESTER AND VINYL ESTER RESINSHasan, T.Correia, J. R.Garrido, M.Cabral-Fonseca, S.Jorge, M.J. SENA-CRUZhttp://repositorio.lnec.pt:8080/jspui/handle/123456789/10193152026-05-05T16:18:05Z2025-07-01T00:00:00ZTitle: HYGROTHERMAL DURABILITY OF VACUUM INFUSED GFRP COMPOSITES PRODUCED WITH POLYESTER AND VINYL ESTER RESINS
Authors: Hasan, T.; Correia, J. R.; Garrido, M.; Cabral-Fonseca, S.; Jorge, M.; J. SENA-CRUZ2025-07-01T00:00:00Z