Artigos de Revista

Desenvolvimento de matérias associadas a um leque de propostas organizativas para as zonas domésticas, sob o ponto de vista de diversos autores especialistas nestas matérias, apontando-se, desde já, a importância deste tipo de reflexões, designadamente, quando aplicadas a soluções habitacionais espacialmente muito condicionadas, como é o caso das soluções de habitação de interesse social.

Mais do que tudo o que, em seguida, se aponte sobre as matérias associáveis à organização doméstica e à sua influência numa expressiva satisfação dos habitantes, na fruição doméstica há aspectos que importa sublinhar por se considerarem determinantes num tal resultado.

O Laboratório Nacional de Engenharia Civil tem uma longa experiência na área da Engenharia Sísmica, sendo uma das instituições de referência, a nível europeu, em todos os campos desta área das Ciências da Engenharia. A investigação europeia em Engenharia Sísmica teve início no final da década de 50, tendo sido o LNEC, na pessoa do Engenheiro Júlio Ferry Borges, o seu principal impulsionador. Desde então, assistiu-se ao estudo dos diferentes aspetos da fenomenologia ligada à caraterização da ação sísmica e ao comportamento das estruturas sujeitas à ação dos sismos, como ilustrado pelas cerca de 50 teses de mestrado e doutoramento nos diferentes domínios da Engenharia Sísmica, desenvolvidas no Núcleo de Engenharia Sísmica e Dinâmica de Estruturas (NESDE), nas duas ultimas décadas, e por mais de uma centena de investigadores visitantes, nacionais e estrangeiros. No âmbito da avaliação do risco sísmico, o LNEC tem tido um papel fundamental a nível nacional, assumindo a liderança da investigação científica nas matérias relacionadas com a perigosidade sísmica, a caraterização da ação sísmica, a avaliação do risco, e o desenvolvimento de estratégias para redução da vulnerabilidade sísmica...

Historical buildings are important fingerprints of the history and culture of a region and its communities. Climatic and environmental conditions are often very severe for construction materials, namely in presence of high humidity or in direct contact with water and salts. However, some historical buildings have in our days a very good condition, probably due to careful construction and/or accurate materials selection and to a specific technology. The knowledge of old mortars composition has a fundamental role on the preservation of cultural heritage, allowing information about the used materials, their performance in their specific environment, conducting to adequate and compatible materials to conservation purposes. This article presents two case studies of historical buildings with important defense functions in Lisbon coast, in which ancient lime mortars where used under severe seaside environmental actions. Mortar samples from these two case studies are characterized and the relationship of their composition with the good performance and high durability observed is discussed.

The article presents the results of a round robin test performed by 13 international research groups (representing fifteen institutions) in the framework of the activities of the RILEM Technical Committee 225-SAP ‘‘Applications of Superabsorbent Polymers in Concrete Construction’’. Two commercially available SAP materials were used for internal curing of a high-performance, fine-grained concrete in combination with the addition of extra water. The concrete had the same mix composition in all laboratories involved but was composed of local materials. All found a considerable decrease in autogenous shrinkage attributable to internal curing. Also, with regard to the shrinkage-mitigating effect of both particular SAP materials, the results were consistent. This demonstrates that internal curing using SAP is a robust approach, working independently of some variations in the concretes’ raw materials, production process, or measuring technique. Furthermore, the effects of internal curing on other properties of concrete in its fresh and hardened states were investigated. These are consistent as well and expand considerably the existing data basis on properties of concrete materials containing SAP.

The effect of alloy surface pre-treatments on the corrosion behaviour of sol gel hybrid coated EN AW 6063 alloy was studied. Five pre-treatments were used: solvent degreasing; alkaline degreasing followed by acid etching; alkaline degreasing followed by alkaline plus acid etching, alkaline degreasing followed by acid etching and oxide growth in boiling water and alkaline degreasing followed by acid etching and anodization. Surface morphology depends on the pre-treatment: SEM/EDS analysis revealed that alkaline plus acid cleaned samples exhibited a very smooth deoxidized surface, while all the others showed a rougher surface covered with an oxide layer. This oxide layer is denser and more homogeneous in the samples subjected to the oxide growth steps. A hybrid sol-gel coating, synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors, was applied to the different pre-treated metallic substrate by dip-coating. The corrosion behaviour of the coated samples was evaluated by Electrochemical Impedance Spectroscopy (EIS) and by an accelerated corrosion test. Complementarily to the corrosion study, the adhesion of the hybrid sol-gel coating was evaluated by cross-cut and bend tests. The corrosion tests revealed that the pre-treatments including the oxide growth steps lead to the best protection performance, followed by the alkaline degreasing and alkaline plus acid etching one. However, the latter exhibits the worst adhesive behaviour, attributed to the smoother and deoxidized surface of the substrate.

This paper presents a literature review and results of an experimental study about the effects of thermal cycles on the physical and mechanical properties of pultruded glass fibre reinforced polymer (GFRP) profiles used in civil engineering structural applications. The GFRP profiles used in this study present similar fibre architecture, differing only in their matrix nature: unsaturated polyester and vinylester. Small-scale coupons obtained from both types of GFRP profiles were exposed to a Mediterranean range of thermal variations (-5 °C to 40 °C) for up to 190 cycles in a dry condition. The effects of such exposure on the physical and mechanical response of the GFRP materials were assessed and compared using the following experimental techniques: (a) dynamic mechanical analyses (DMA) to assess the viscoelastic behaviour; (b) tensile, flexural and interlaminar shear tests, to evaluate the mechanical properties; and (c) scanning electron microscopy (SEM), to monitor the potential changes in the microstructure due to the degradation (if any) caused by the thermal cycles, as well as the possible changes into the main mechanisms of fracture. After exposure to thermal cycles, the viscoelastic behaviour of the GFRP profiles presented only slight changes, indicating no significant degradation, neither in the matrix structure nor at the fibre-matrix interphase. In terms of mechanical properties, both types of GFRP materials suffered slight changes regarding tensile and interlaminar shear properties. Flexural properties were more affected, particularly the flexural modulus, especially in the first cycles, as degradation tended to stabilize for increasing cycles. The GFRP profile made of vinylester resin presented better overall performance than the one made of polyester, especially regarding the tensile properties. SEM observations of the surfaces of fracture of mechanically tested pultruded specimens showed two main mechanisms of crack propagation: cohesive rupture (matrix cracking), where the crack propagates inside the matrix, and adhesive rupture (fibre-matrix debonding), where the crack propagates at the interface fibre-matrix. Degradation of the polyester matrix caused by the thermal cycles is evidenced by extensive matrix microcracking and increased fibre-matrix debonding. The vinylester matrix resists better to such degradation as fibre-matrix debonding occurs in less extent, and matrix microcracking is scarcely present.

Apesar da extensa utilização no léxico técnico, o conceitode eficiência energética nos edifícios sendo fácil deapreender é difícil de quantificar e de utilizar na comparaçãoe classificação de edifícios. A eficiência energéticado edifício é o quociente entre o serviço prestado (confortotérmico, qualidade do ar, água quente sanitária) e oconsumo de energia associado. Resulta, que a eficiênciaenergética depende das características do edifício, dosseus equipamentos de climatização (e todos os outros),mas também dos ocupantes, das suas preferências deconforto e da forma como estes utilizam (ou não) os dispositivose controlos à sua disposição. Este aspeto dosocupantes é decisivo na avaliação da eficiência energéticados edifícios e nas soluções ótimas.Desde o RCCTE de 1990 que a avaliação do desempenhotérmico e energético dos edifícios é realizada comparandoo indicador necessidades térmicas nominais do edifícioface a um valor de referência, admitindo que existe

Background: Indoor air quality (IAQ) is considered an important determinant of human health. The association between exposure to volatile organic compounds, particulate matter, house dust mite, molds and bacteria in day care centers (DCC) is not completely clear. The aim of this project was to study these effects. Methods --- study design: This study comprised two phases. Phase I included an evaluation of 45 DCCs (25 from Lisbon and 20 from Oporto, targeting 5161 children). In this phase, building characteristics, indoor CO2 and air temperature/relative humidity, were assessed. A children’s respiratory health questionnaire derived from the ISAAC (International Study on Asthma and Allergies in Children) was also distributed. Phase II encompassed two evaluations and included 20 DCCs selected from phase I after a cluster analysis (11 from Lisbon and 9 from Oporto, targeting 2287 children). In this phase, data on ventilation, IAQ, thermal comfort parameters, respiratory and allergic health, airway inflammation biomarkers, respiratory virus infection patterns and parental and child stress were collected. Results: In Phase I, building characteristics, occupant behavior and ventilation surrogates were collected from all DCCs. The response rate of the questionnaire was 61.7% (3186 children). Phase II included 1221 children. Association results between DCC characteristics, IAQ and health outcomes will be provided in order to support recommendations on IAQ and children’s health. A building ventilation model will also be developed. Discussion: This paper outlines methods that might be implemented by other investigators conducting studies on the association between respiratory health and indoor air quality at DCC. © 2013 Sociedade Portuguesa de Pneumologia. Published by Elsevier España, S.L. All rights reserved.

Children attending day care centers (CDCC) have been reported to be more prone to infectious diseases when compared with those cared for at home, and are exposed to conditions that may increase the risk of allergies and asthma. Several studies revealed that consequences of poor ventilation conditions include high levels of carbon dioxide (CO2) and many other indoor pollutants commonly detected in schools. Nine child day care centers were selected randomly to participate in this study. Fifty-two classrooms were assessed for chemical, biological, physical, and allergen parameters in spring and winter seasons in these nine CDCC located in Porto, Portugal. Outdoor measurements were also conducted for comparison. Our results indicated that (i) particulate matter (PM10) median levels were above the national reference levels, both by classroom type and by season; (ii) TVOC kindergarten peak values may raise some concern; (iii) CO2 was present at high median and maximum levels during spring and winter assessment in both nurseries and kindergartens classrooms; (iv) total bacteria concentrations were 57- and 52-fold higher in the nursery and kindergarten than outdoors, respectively, for the spring season; (v) winter and spring median predicted mean vote (PMV) indices were between “neutral” (0) and “slightly cool” (? –1) in the thermal sensation scale for comfort situations (?2 to 2) for both types of classrooms; (vi) there were significant differences for both PMV and predicted percentage of dissatisfied (PPD) indices by season; and (vii) CO2, total bacteria, and gram-negative bacteria were associated with low airflow rates. These data will help to evaluate the effectiveness of current building operation practices in child day care centers regarding indoor air quality and respiratory health.