Artigos de Revista

This work investigates the recent morphological changes at the inlet of a complex coastal system (Ria de Aveiro lagoon, Portugal). This study was carried out usingbathymetric data analysis and numerical simulationsobtained with the 2DH morphodynamic modelling systemMORSYS2D. The present simulations considered only tidalforcing, and a sensitivity analysis was performed by tuningthe formula used to compute the sediment transports. Anon-uniform sediment grain size distribution for the Ria deAveiro inlet is considered in the numerical simulations,based on surveys performed in this area. The model resultsare analysed to assess if they resemble the observed trendsof erosion and deposition, as calculated from bathymetricdata. A quantitative analysis of the differences between thebathymetric changes obtained through surveys and thenumerical results over a period of 3 years consideringdifferent sediment transport formulations shows that theformulations of Ackers and White (1973) and Engelundand Hansen (1967) are the ones that best describe themorphodynamic changes driven by tides in the Ria deAveiro inlet.

Reliable flood forecasting requires hydraulic models capable to estimate pluvial flooding fast enough in order to enable successful operational responses. Increased computational speed can be achieved by using a 1D/1D model, since 2D models are too computationally demanding.Further changes can be made by simplifying 1D network models, removing and by changingsome secondary elements. The Urban Water Research Group (UWRG) of Imperial College London developed a tool that automatically analyses, quantifies and generates 1D overland flow network.The overland flow network features (ponds and flow pathways) generated by this methodology are dependent on the number of sewer network manholes and sewer inlets, as some of the overland flow pathways start at manholes (or sewer inlets) locations. Thus, if a simplified version of the sewer network has less manholes (or sewer inlets) than the original one, the overland flow network will be consequently different. This paper compares different overland flow networksgenerated with different levels of sewer network skeletonisation. Sensitivity analysis is carried out in one catchment area in Coimbra, Portugal, in order to evaluate overland flow network characteristics.

A recarga natural constitui os recursos hídricos subterrâneos naturais renováveis. Pode-se considerar, como fontes de recarga, a recarga por infiltração da água da chuva, a recarga a partir de cursos de água (cursosde água influentes), e no caso de aquíferos multicamada a recarga a partir da drenância de camadas adjacentes. A recarga por infiltração da água da chuva refere-se à quantidade de água que se infiltra abaixo do solo após os processos de evapotranspiração e de escoamento directo, e que vai ter um percurso subterrâneo, podendo,em condições de não exploração, ficar armazenada no aquífero ou constituir escoamento subterrâneo que posteriormente aflora à superfície, contribuindo para o escoamento dos cursos de água (escoamento de base). O sistema Tejo-Sado é constituído pelos seguintes três sistemas aquíferos definidos em Almeida et al. (2000): Aluviões do Tejo, Bacia do Tejo-Sado/Margem Esquerda e Bacia do Tejo-Sado/Margem Direita.Esta comunicação divide-se fundamentalmente em duas partes: (1) a caracterização da recarga para a primeira geração dos Planos de Bacias Hidrográficas do rio Tejo (aprovado pelo Decreto Regulamentarnº 18/2001, de 7 de Dezembro), com uma descrição sumária das metodologias utilizadas (Oliveira et al., 1999), e (2) uma perspectiva das metodologias utilizáveis para o cálculo da recarga do Plano de Gestão de Região Hidrográfica do rio Tejo e da segunda geração do Plano de Bacia Hidrográfica das ribeiras do Oeste, em conformidade com os objectivos destes planos e fazendo uso das metodologias sugeridas para o seu cálculo.

O tratamento das águas residuais domésticas pode ser feito através de sistemas localizados (onsite),não se verificando neste caso a utilização de redes públicas de colectores. Em Portugal é vulgar a utilização de fossas sépticas particulares como sistema de disposição das águas residuais domésticas no meio ambiente, em situações tão díspares que vão desde as habitações isoladas até às zonas periféricasde aglomerados urbanos, passando ainda pelo seu emprego generalizado em povoações dereduzida dimensão. Existe ainda um conjunto bastante diversificado de tecnologias disponíveis para o tratamento das águas residuais domésticas em unidades compactas prefabricadas que podem ser utilizadas em sistemas localizados.A norma EN 12566 estabelece os requisitos gerais relativos a instalações e equipamentos auxiliares utilizados no tratamento de águas residuais domésticas para uma população total equivalente (PTE)igual ou inferior a 50. Esta norma está organizada num conjunto de Normas Europeias e de Relatórios Técnicos que cobrem diferentes tipos de sistemas de tratamento e de disposição no ambiente de águas residuais domésticas.No artigo é feita uma apresentação da norma europeia EN 12566, sendo enfatizada a importância da normalização na uniformização do mercado europeu.

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The degradation of concrete structures caused by delayed ettringite formation (DEF) is a problem that nowadays affects many concrete structures worldwide. This pathology is due to the formation of an expansive compound – ettringite - inside the material. This is a hydrated calcium sulphoaluminate produced by the chemical reaction between sulphate ions, calcium hydroxide and alumina present in the Portland cement paste. This product, normally formed during the hydration of cement, presents an acicular morphology (needles) that can be observed by scanning electron microscopy (SEM). However, DEF can also be formed after the setting of the cement causing, in this case, a deleterious expansion of the concrete. This secondary ettringite can also be produced after an excessive heating of the concrete, caused by a high amount of cement or by the use of heat cure. SEM has been used to distinguish between expansive and non expansive ettringite based normally in morphology analysis, since the former is characterized by a compressed or compact nature where the needle shapes disappear or are welded together. Furthermore, the use of other techniques, like X-ray diffraction or micro-XRF, has been limited because the compressed or compact ettringite is badly crystallized or even amorphous and the elemental composition is similar and therefore it is difficult to detect. This article presents a methodology for the diagnosis of DEF using polished concrete thin sections and combining polarised and fluorescence light optical microscopy with SEM-EDS.

The degradation of concrete structures caused by delayed ettringite formation (DEF) is a problem that nowadays affects many concrete structures worldwide. This pathology is due to the formation of an expansive compound – ettringite - inside the material. This is a hydrated calcium sulphoaluminate produced by the chemical reaction between sulphate ions, calcium hydroxide and alumina present in the Portland cement paste. This product, normally formed during the hydration of cement, presents an acicular morphology (needles) that can be observed by scanning electron microscopy (SEM). However, DEF can also be formed after the setting of the cement causing, in this case, a deleterious expansion of the concrete. This secondary ettringite can also be produced after an excessive heating of the concrete, caused by a high amount of cement or by the use of heat cure. SEM has been used to distinguish between expansive and non expansive ettringite based normally in morphology analysis, since the former is characterized by a compressed or compact nature where the needle shapes disappear or are welded together. Furthermore, the use of other techniques, like X-ray diffraction or micro-XRF, has been limited because the compressed or compact ettringite is badly crystallized or even amorphous and the elemental composition is similar and therefore it is difficult to detect. This article presents a methodology for the diagnosis of DEF using polished concrete thin sections and combining polarised and fluorescence light optical microscopy with SEM-EDS.

Presently, mechanically fastened waterproofing systems are widely used in large roofs, mostly in industrial and commercial buildings. This paper presents a study of this constructive system that included the analysis of the mechanisms of response to wind loads and the effects of the different components on the system’s wind resistance. Wind up lift tests were performed on mechanically fastened waterproofing systems, according to the guideline for European technical approval (ETAG 006), in order to evaluate the influence of both the thermal insulation thickness (from 40 mm to 100 mm) and the characteristics of the atactic polypropylene (APP) modified bitumen waterproofing membranes (different constitutions, single/double layer) on the resistance to wind up lift. All tested mock-ups failed due to peeling of the overlapping membranes. Within the range of analysed systems, the thickness of the thermal insulation and the characteristics of the waterproofing membranes did not present a noticeable effect on the resistance of the tested mock-ups. Results obtained in the experimental tests were compared to other results gathered from European technical approvals. Additionally, results were used to define the field of application of the tested systems to a National level, based on the wind loads defined in the Portuguese code and the design procedure presented in Eurocode 1 and ETAG 006.

In November 2008 the European Parliament and the Council have adopted the Directive 2008/96/EC aiming at the improvement of road infrastructures safety management in the Trans-European Road Network, by setting up appropriate procedures which can be extended to national networks, namely through the application of guidelines by the Member States. Research and dissemination of research results play an important part in this process. At the Transportation Department of the National Laboratory for Civil Engineering (LNEC), in Portugal, a special attention has been given, over the time, to road infrastructure safety issues, either in the scope of European projects in this area or through studies within collaboration agreements with road and traffic administrations. Based upon this experience, in this article a concise description is made of the main aspects of the EU Directive and on related research studies, which provided sound scientific and technical basis for the proposed procedures, thus contributing to the overall objective of a continuous and widespread improvement of road safety.