Papers

Tidal asymmetry is a key factor in the geomorphology of many coastal lagoons. Whilst tidal asymmetry insemi-diurnal tidal regimes has been extensively studied, its occurrence in mixed tidal regimes is less wellunderstood, and has a number of unique causes and characteristics. Tidal phase duration analysis andleast squares harmonic analysis have been used to study the temporal and spatial nature of asymmetryin both offshore and coastal lagoon tides at the Murray Mouth in south-eastern Australia. GIS analysis ofbathymetric survey data has been used to study the roles of lagoon bathymetry on tidal distortion.Tidal asymmetry in the Murray Mouth coastal lagoon results from frequency relationships between majorastronomical driving tides as well as bathymetry-induced tidal transformations. The frequency differencebetween the K1 and S2 tides produces an important 6-monthly ebb/flood-dominant asymmetry cycle in theincoming oceanic tides, whilst phase relationships between the K1 and K2 tides contribute to persistentasymmetry. The use of standard relationships between theM2 andM4 tides as asymmetry indicators is shown tobe invalid for this mixed tidal regime. In this shallow, microtidal system, the impacts of bathymetry on tidalasymmetry within the lagoon are profound, with inlet and channel configurations identified as the mostimportant controlling factors.The results of this study may inform the strategic management of tidal inlets in mixed tidal regimes, suchas the Murray Mouth, that are subject to intermittent or long-term constriction.

Unstabilised rammed earth is a recyclable, economical and eco-friendly building material, used in the past and still applied today. Traditionally, its use was based on a long empirical knowledge of the local materials. Because this knowledge was mostly lost or is no longer sufficient, in many countries normative documents have been produced to allow the assessment of rammed earth soils. With the aim of contributing for a refining of these normative requirements, this article presents a research work that included: (i) collection of unstabilised rammed earth samples from six constructions in Portugal; (ii) a literature survey of normative and complementary documents to identify the most mentioned key-properties, the test procedures and the corresponding threshold limits; (iii) a discussion of the test procedures and of the thresholds limits in the light of the experimental results. The analyzed properties are the particle size distribution, maximum particle size, plasticity, compaction, linear shrinkage, organic content and salt content. The work highlights the advantages of taking into account the characteristics of existing constructions as a basis for the establishment and further refining of consistent threshold values. In particular, it shows that it is essential to adjust the requirements to the specificities of local materials.

Unstabilised rammed earth is a recyclable, economical and eco-friendly building material, used in the past and still applied today. Traditionally, its use was based on a long empirical knowledge of the local materials. Because this knowledge was mostly lost or is no longer sufficient, in many countries normative documents have been produced to allow the assessment of rammed earth soils. With the aim of contributing for a refining of these normative requirements, this article presents a research work that included: (i) collection of unstabilised rammed earth samples from six constructions in Portugal; (ii) a literature survey of normative and complementary documents to identify the most mentioned key-properties, the test procedures and the corresponding threshold limits; (iii) a discussion of the test procedures and of the thresholds limits in the light of the experimental results. The analyzed properties are the particle size distribution, maximum particle size, plasticity, compaction, linear shrinkage, organic content and salt content. The work highlights the advantages of taking into account the characteristics of existing constructions as a basis for the establishment and further refining of consistent threshold values. In particular, it shows that it is essential to adjust the requirements to the specificities of local materials.

Water services are a strategic sector of large social and economic relevance. It is therefore essentialthat they are managed rationally and efficiently. Advanced water supply and wastewaterinfrastructure asset management (IAM) is key in achieving adequate levels of service in the future,particularly with regard to reliable and high quality drinking water supply, prevention of urbanflooding, efficient use of natural resources and prevention of pollution. This paper presents amethodology for supporting the development of urban water IAM, developed during the AWARE-Pproject as well as an appraisal of its implementation in four water utilities. Both water supply andwastewater systems were considered. Due to the different contexts and features of the utilities, themain concerns vary from case to case; some problems essentially are related to performance, othersto risk. Cost is a common deciding factor. The paper describes the procedure applied, focusing onthe diversity of drivers, constraints, benefits and outcomes. It also points out the main challengesand the results obtained through the implementation of a structured procedure for supporting urbanwater IAM.

The degradation of large concrete structures over time is well known. One of the main reasons is the reaction that occurs between the cement paste and some reactive siliceous aggregates, which causes a significant expansion that depends on the employed materials and exposure conditions of the structure. This process is known as alkali-silica reaction (ASR) and affects several structures worldwide, including major dams and bridges in long time run. In this work the effect of fly ashes from biomass combustion in the mitigation of the ASR was investigated. The fly ashes were collected from two industrial plants located in the central area of Portugal: (i) a thermal power plant (BFA1), (ii) co-generation process of a pulp and paper industry (BFA2). The fly ashes were characterized by different techniques to determine the following properties: particle size distribution (laser interference), loss on ignition and thermal behaviour (TG/DTA), chemical (XRF) and phases (XRD) composition and pozzolanic activity (EN 196-5:2005). These biomass fly ashes were irregular in shape and fine in size. The chemical characterization revealed significant differences in CaO and SiO2 contents, but both fly ashes can be considered as class C fly ashes if compared with those generated from the coal combustion. Accelerated mortar-bar tests were conducted according to ASTM C1260/ASTM C1567 to evaluate the behaviour of the biomass fly ash in the ASR inhibition mechanism. The expansive behaviour was studied on mortars where the cement was partially replaced (20–30 wt%) by the biomass fly ashes. This substitution tends to reduce the expansion upon accelerated curing conditions, and BFA2 is more effective than BFA1. But the incorporation of biomass fly ash in the blend along with metakaolin (MK), 20% BFA + 10% MK did a significant improvement in the expansion results, indicating the effective use of biomass fly ash along with metakaolin in mitigating the ASR.

É interessante pensar nesta matéria do viver intensamente, também o exterior, como uma extensão, natural, da ideia que, há alguns anos, incidiu sobre o exterior urbano, recomendando que ele fosse pormenorizado e equipado com todo o cuidado; uma ideia que esteve frequentemente associada aos muitos casos de inacabamento crítico de conjuntos urbanos e habitacionais de interesse social que aconteceram (e ainda acontecem) em Portugal. E lembrando-nos que vivemos o século das cidades e das mega-cidades, assim como o século das cidades informais, potencialmente tão marcadas por este tipo de intervenções, os referidos objectivos de vivência intensa e agradável do espaço urbano, recolhem, ainda, uma oportunidade e urgência muito acrescidas e que merecem posterior desenvolvimento.

Esta matéria da segurança urbana e residencial é uma temática que não teria razão de abordagem há alguns anos atrás, desde que se retirando dela, como é o caso, as questões ligadas ao trânsito de veículos. E não tenhamos quaisquer dúvidas de que é fundamental tudo fazer para dinamizar o uso dos espaços exteriores públicos, numa desejável teia de sequências de espaços de vizinhança, pois de uma tal opção depende em boa parte a fundamental revitalização da cidade e, naturalmente, as suas condições de segurança e de agradabilidade no uso corrente.

Tem-se a certeza de que, neste texto/temática se abordaram matérias tão diversas como fundamentais para melhor se habitar/viver o (n)o espaço urbano, matérias que, individualmente, exigem aprofundamento, mas que só quando associadas (ex., diversidade social + densidade equilibrada mas agradavelmente afirmada + desenho/forma/acabamentos que agradem e emocionem habitantes e que dignifiquem a cidade) poderão ter os resultados mais efectivos na satisfação e no fazer cidade, sendo que tal associação exige também cuidadoso aprofundamento e sistemática exemplificação.

It has long been thought that the evaporation rate from mesoporous materials during the constant drying rate period (CDRP) is equal to that of a free-water surface, due to the presence of a liquid film covering the surface of the material. In this article we review several early articles and demonstrate that the experimental scrutiny this hypothesis has received is insufficient. Further, we report a set of evaporative drying experiments on eight building materials whose results also do not confirm such hypothesis. Indeed, the drying rate during the CDRP is not equal either among the tested materials or between these and the free-water surfaces. To explain the differences in drying rate, we have looked at the influence of surface texture and porosity. We have concluded that surface texture, which could increase the effective surface area of the materials, did not have a relevant effect on the CDRP drying rate. However, we have found a good correlation between the CDRP drying rate and capillary porosity. This is consistent with the hypothesis that drying occurs at the pore level during the CDRP. Further, it contradicts the suggestion that there is a film of water covering the surface of the materials during this period.

This paper describes an application of theBoussinesq-type COULWAVE model to study the wavehydrodynamics in the vicinity of a multi-functional artificialreef (MFAR). This reef is under investigation and consists ofa supplementary protection solution for the Leirosa sanddune system located at South of Figueira da Foz, on thePortugueseWest coast. Such installation near the coastline isexpected to contribute to enhance the surfing conditions inthe area, protect the sand dune system in the surroundings ofLeirosa beach, and increase its environmental value.Numerical calculations with the COULWAVE model wereperformed for four test cases, considering two reef geometries(differing in the reef angle) and two incident waveconditions (storm condition and a common wave condition).Comparisons between the results obtained, in terms of waveheights and breaking line positions allow us to assess theinfluence of the reef on the hydrodynamics near the beachand around the reef. Moreover, the reef performance wasanalysed in terms of surfability and coastal protection. Thesurfability parameters (breaker height, Iribarren number andpeel angle) were calculated for each test case using thenumerical wave heights, wave directions and wave breakingpositions. Comparisons of parameters allow characterizingthe most appropriate configuration of the reef to improve thesurfing conditions in the study area. A methodology basedon numerical free surface elevations and horizontal velocitycomponents was developed to calculate wave directions,since this is not a direct output of the COULWAVE model.Concerning coastal protection, analyses of the mean currentsaround the reef were used together with observationsof the velocity cells near the shoreline as an indication of thesediment transport.