Artigos de Revista

A performance assessment system (PAS) is an important instrument to provide a costeffective and sustainable management of wastewater treatment plants (WWTPs). Despite the fact that many PASs have been developed in recent years, important aspects of WWTPevaluation have not yet been considered. This paper presents the framework and the overall performance indicators of a PAS developed for urban WWTPs.

An electrochemical study of prestressed steel in saturated Ca(OH)2 aqueous solutions (pH 12) was carried out in the absence and in the presence of chloride ions, in such a concentration that simulates the composition of seawater. Cyclic voltammetry, linear sweep voltammetry, open circuit potential transients, atomic absorption spectroscopy and scanning electron microscopy coupled to electron diffraction spectroscopy were employed. The linear polarisation curves analysis led to the determination of polarisation resistance, Rp, corrosion potential, Ecorr, corrosion current density, jcorr, Tafel slopes, breakdown potential, Eb and repassivation potential Erepass. A linear dependence of the breakdown potential, Eb, on the square root of scan rate was obtained, according to the Point Defect Model (PDM). A crossover characteristic of the nucleation processes was observed in the presence of chloride ions. SEM/EDS studies revealed, as expected, a strong influence of the presence of chloride ions observed in the transpassive and the active regions. In conclusion, chloride ions contribute to enhance the corrosion of steel, most probably due to their adsorption on both the active and the passive electrode surfaces.

Tal como em muitas outras áreas, no domínio dos sistemas e serviços urbanos de água(abastecimento de água e de gestão de águas residuais) a actividade normativa desempenhaum papel importante na eliminação de barreiras técnicas ao comércio de produtos e serviços,através da uniformização de procedimentos e critérios. Também as crescentes exigências emtermos de Qualidade têm vindo a demonstrar a necessidade da existência de uma estruturanormativa adequada em que se apoiem os processos de certificação. O presente artigo tem porobjectivo fazer a apresentação da actividade de normalização em curso neste domínio levada acabo pela Comissão Técnica CT90

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The use of adhesives to produce assembled structural joints in the building industry is increasing, particularly in the context of on-site rehabilitation of timber structures. On their own or together with steel or fibre reinforced polymer composite connecting materials, adhesives can provide low intrusive, fast, versatileand effective on-site repair or reinforcement interventions to timber structures. Most common applicationsinvolve sealing and repair of cracks, drying fissures and delamination of glued laminated members; replacement of decayed beam ends; strengthening of timber members; and repair and strengthening of mechanical timber joints. The performance of bonded joints highly depends on their design and detailing, surfaces preparation, selection and application of adhesives, and full compliance with their cure schedule. Therefore, the work should be carried out by well-informed, trained and certified operators following a QualityAssurance Program to ensure satisfactory end-product strength and durability.Despite some recent developments, the exploitation of the full potential for on-site bonded joints is mainlyrestrained at present by the lack of structural design guidance, standards for durability assessment and onsiteacceptance testing.This article discusses briefly the use of adhesives on the construction site in the context of structural repair and reinforcement; the requirements and practical difficulties in the work on site with regards to the strength and durability of the rehabilitated timber structure; and the consequent need for quality control. It also highlights the characteristics and requirements that must be fulfilled by structural adhesives and reinforcingmaterials; factors affecting performance and durability of bonded joints; and ways to improve adhesion and durability. Finally, it points out some research needs and future developments identified by the authors.© Koninklijke Brill NV, Leiden, 2010

The use of adhesives to produce assembled structural joints in the building industry is increasing, particularlyin the context of on-site rehabilitation of timber structures. On their own or together with steel orfibre reinforced polymer composite connecting materials, adhesives can provide low intrusive, fast, versatileand effective on-site repair or reinforcement interventions to timber structures. Most common applicationsinvolve sealing and repair of cracks, drying fissures and delamination of glued laminated members; replacementof decayed beam ends; strengthening of timber members; and repair and strengthening of mechanicaltimber joints. The performance of bonded joints highly depends on their design and detailing, surfacespreparation, selection and application of adhesives, and full compliance with their cure schedule. Therefore,the work should be carried out by well-informed, trained and certified operators following a QualityAssurance Program to ensure satisfactory end-product strength and durability.Despite some recent developments, the exploitation of the full potential for on-site bonded joints is mainlyrestrained at present by the lack of structural design guidance, standards for durability assessment and onsiteacceptance testing.This article discusses briefly the use of adhesives on the construction site in the context of structural repairand reinforcement; the requirements and practical difficulties in the work on site with regards to the strengthand durability of the rehabilitated timber structure; and the consequent need for quality control. It alsohighlights the characteristics and requirements that must be fulfilled by structural adhesives and reinforcingmaterials; factors affecting performance and durability of bonded joints; and ways to improve adhesion anddurability. Finally, it points out some research needs and future developments identified by the authors.

Abstract. Many historical buildings with renders based in air lime still exist in Portugal. These old mortars have proved to be durable and reliable materials. However, new lime mortars prepared nowadays to be used in conservation practice, often present low strength in comparison with cement mortars.This paper presents a study of the viability of improving the performance of lime mortars througth the use of different nature aggregates (Tagus river siliceous sand and crushed calcareous sand) as well as different size distributions, varying the filler contents. For that purpose a set of mortars with volumetric proportion of 1:3 (lime:aggregate), using silicious sand from Tagus river or calcareous sand and including different volume percentages of aggregate replacement by filler (0% of incorporation, 5% of incorporation, 10% of incorporation), were prepared. An evaluation of the main characteristics of this set of mortars was made in terms of: i) hygric behaviour (water absorption by capillarity), and ii) mechanical resistance (flexural and compressive strength and elastic modulus). This study aims to assess the viability and possible advantages of using calcareous aggregate in lime mortars and to evaluate the possibility of improving characteristics through a better compaction obtained by the incorporation of different ratios of filler.

As áreas mineiras degradadas (AMD) são locais ambientalmente problemáticos que exigem, na maioria das vezes, estudos de caracterização complexos. O recurso a métodos expeditos, que permitem obter dados fiáveis e a baixo custo, numa fase precoce desses estudos, facilitam a gestão das tarefas subsequentes. É o caso dos analisadores portáteis de fluorescência de raios-X (APFRX), que permitem determinar semi-quantitativamente a concentração em metais pesados e metalóides em solos e resíduos mineiros, in situ e ex situ. A qualidade dos dados obtidos in situ e ex situ foi demonstrada em trabalhos anteriores. Na presente comunicação apresentam-se os trabalhos desenvolvidos na área mineira de Santo António, em que se obteve um zonamento da contaminação área, facilitando-se o diagnóstico preliminar do respectivo estado de degradação e a optimização de um programa de amostragem específico.

A simple analytical formulation that reproduces a skewed, nonlinear near-bed wave orbital velocity is presented. It contains four free parameters, where two are solely related to the velocity and accelerationskewnesses. The equation is compared with other models and is validated against field and laboratoryexperiments. The results reveal that it can simulate a wide range of nonlinear wave shapes, reproducing satisfactorily the measured nonlinear wave particle velocity. Also, the new expression overcomes somelimitations of the other models. The new formulation is therefore capable of being used in many engineering applications that require the use of representative wave forms.

RESUMONuma construção pré-esforçada a armadura é uma componente da ancoragem dominante na segurança dos elementos suportados. A armadura pode ser de vários tipos. No mercado existem diversas tecnologias e sistemas, pelo que a armadura deve ser seleccionada em conformidade com as cargas e com o disposto pelos documentos regulamentares e normativos. A sua durabilidade reveste-se de importância vital na longevidade da obra, sendo necessária protecção contra a corrosão. O comportamento do aço de pré-esforço relativamente à corrosão depende: da qualidade das caldas de injecção; do grau de preenchimento das bainhas; do recobrimento da armadura e das cabeças. A função das ancoragens e o tempo de vida da estrutura ancorada têm uma implicação directa na tecnologia a implementar. Construída a ancoragem, verifica-se o seu comportamento mecânico com ensaios de carga, para avaliar e verificar se as exigências de projecto são respeitadas.