Publications

Among the test-methods for evaluation of aggregates reactivity towards alkali-silica reaction (ASR), linear dilatation of mortar bars or concrete prisms is often used in several tests under various conditions, criteria and procedures of measuring and accelerating the reaction. As reactivity is an essentially kinetic property, the expansion limits in such tests, or even tests results for the same aggregate, should be kinetically inter-related. This paper presents a proposal of a kinetic relationship for critical reaction rates, evaluated from criteria of standard test-methods NF P 18-590, ASTM C 1260 and ASTM C 1293 . To do so, the critical expansion rate of these tests were corrected for a reference 1M alkalinity and depicted as Arrhenius plot. The high correlation of the regression line shows linearity of the plotted data, which was assumed as a criterion of kinetic compatibility between the said tests. The discussion includes a comparison with other tests and literature comments on their evaluation. The main interest of this study concernong the potential for ASR, is to discuss and compare methods aiming to improve the service life of concrete structures, by: i) selection of good materials; ii) decisions on the appropriate concrete formulation; iii) foreseeing possible problems allowing to plan monitoring and/or the need for adequate intervention as well as the possibility of test improvements. The extension of service life allows savings in raw materials and energy, improvement of the investment economics and, in the long term, lower investment requirements.

This paper presents the reaction behavior of lime and metakaolin (MK) pastes submitted to long term aging at ambient temperature and relative humidity of 95 ± 5%. The results presented are the basis for an extensive research pointing towards the formulation of lime based mortars for conservation of historic buildings, namely in humid environments. MK, when mixed with calcium hydroxide, in the presence of water, originates a set of major hydrated compounds, specifically, stratlingite, monocarboaluminate and calcium aluminate hydrate. The type of hydrated compounds formed is dependent on the lime/MK ratio, being some of them unstable over time. This instability can compromise the mechanical properties of lime–MK mortars. From this work different reaction kinetics with aging were perceived, being the best results in terms of the pozzolanic reaction obtained with 50% MK content. Pastes with less than 25% of MK also present reliable stability.

This paper investigates the mechanical and mineralogical characteristics of natural hydraulic lime NHL3.5 (NHL) mortars with different% of lime replacement by metakaolin (MK) under different laboratory and natural marine curing conditions. Tests were conducted at different curing ages, using compressive and flexural strength tests and thermogravimetric and X-ray diffraction techniques. NHL mortars cured at high humidity levels in natural and artificial environments present interesting results and some could be used in old masonries repair. The incorporation of MK improves the NHL mortars strength, being this increase mostly associated to the pozzolanic reaction.

The new version of EN 459-1 standard for building limes redefined the classes of hydraulic limes and made the producers reformulate or reclassify their natural hydraulic limes. This work evaluates the mechanical, physical and microstructural behavior of mortars formulated with a recently produced natural hydraulic lime NHL3.5 that conforms to EN 459-1, submitted to natural marine environment, humid and standardized conditions, and also the benefits and drawbacks of adding metakaolin in partial replacement of lime. Mortars with NHL3.5 present positive results at young ages. The metakaolin addition increases strength while decreasing the capillary water coefficient. The behavior in an aggressive marine environment seems promising.

This paper is a review of the most recent and relevant achievements (from 2001 to 2013) on the development of organic–inorganic hybrid (OIH) coatings produced by sol–gel-derived methods to improve resistance to oxidation/corrosion of different metallic substrates and their alloys. This review is focused on the research of OIH coatings based on siloxanes using the sol–gel process conducted at an academic level and aims to summarize the materials developed and identify perspectives for further research. The fundamentals of sol–gel are described, including OIH classification, the interaction with the substrate, their advantages, and limitations. The main precursors used in the synthesis ofOIHsol–gel coatings for corrosion protection are also discussed, according to the metallic substrate used. Finally, a multilayer system to improve the resistance to corrosion is proposed, based on OIH coatings produced by the sol–gel process, and the future research challenges are debated.

This work evaluates the influence of binder:aggregate ratio on the mineralogical and mechanical properties of air lime–metakaolin mortars. Mineralogical analysis showed that binder:aggregate ratio affects the extent of carbonation and pozzolanic reactions with curing. The pozzolanic reaction occurs mostly at lower curing times (28 days), while, at higher curing ages, carbonation reaction is mostly dominant. The exceptions are mortars with 1:1 (air:- lime) volumetric ratio with 30% and 50% MK in which the pozzolanic reaction is still dominant. The reduction in the mechanical resistance of some compositions observed from 28 to 90 days is related to the calcium aluminate hydrate instability in the presence of free lime. This instability is expected to disappear after the total consumption of free lime, either by pozzolanic or carbonation reaction.

In Portugal, volcanic rocks are commonly used as concrete aggregates for concrete in Madeira and Azores Islands and in a lesser extent in the Mainland. Nonetheless, the information about the potential alkali-silica reactivity of Portuguese volcanic rocks is rather scarce. In order to ful ll this lack of information and in the scope of a Portuguese research project, four volcanic aggregates from the Portuguese Mainland and Madeira Archipelago were investigated. For this purpose petrographic characterization (polarizing microscopy complemented by bulk chemical analysis and scanning electron microscopy with energy dispersive detector) along with expansion laboratory tests were carried out. In this paper, results of the investigation are presented aiming to establish a possible correlation among the results from the used methods.

As rochas graníticas representam em Portugal cerca de 40% do volume total de agregados para concreto. Estas rochas são normalmente consideradas como sendo de reação lenta ou até como não reativas aos álcalis. Contudo, diversos casos de reação álacalis-agregado (RAA) têm sido diagnosticados em estruturas de concreto nas quais foram utilizadas rochas graníticas. Com o objetivo de diminuir a incerteza na avaliação da reatividade potencial aos álcalis de granitos foi desenvolvido um projeto de investigação no qual os resultados deste artigo se inserem. No âmbito deste projeto foram estudadas trinta e uma amostras colhidas em diferentes regiões de Portugal, apresentando-se neste artigo os resultados de oito dessas amostras. Os ensaios realizados incluem a caraterização petrográfica dos agregados e ensaios de expansão de barra de argamassa e prisma de concreto. Conclui-se que o conteúdo em quartzo microcristalino se correlaciona melhor com os resultados do ensaio em prisma de concreto RILEM AAR-4.1 do que com os outros ensaios de expansão.

A kinetic based comparison between expansion tests for alkali-aggregate reactivity was carried out deriving critical rates from test criteria, in an earlier paper. The present paper checks the assumptions and models of that earlier comparison against results with real aggregates varying in alkali reactivity. Using the same approach, for each aggregate, expansion rates for three expansion tests were estimated, corrected for alkalinity and depicted as an Arrhenius plot. The relationship used data from NF P18-590, ASTM C 1260 and ASTM C 227 expansion test-methods and shows linear Arrhenius plots for several aggregates, aligned almost parallel to the line obtained for test criteria. Aspects related to the different experimental conditions on test-methods and their effects are discussed. The proposed conclusion is that both standards and aggregate results, in the given conditions, are not inconsistent from the kinetic point of view. Some suggestions are made for improving the accuracy of the relationship obtained.

In this study synthetic fine and coarse zeolite pellets were chosen in the development of air lime–metakaolin mortars for repairing ancient masonry to be used in conservation and restoration of cultural heritage. Synthetic zeolite was used due to their particular water adsorption properties and act as an artificial pozzolan promoting the development of hydraulic phases. Physical, chemical, mineralogical and microstructural tests were accomplished to characterize the materials used in mortars’ preparation. Flexural, compressive strength and dynamic modulus of elasticity tests were performed in mortars at 28, 90 and 180 days of curing. Incorporation of both fine and coarse zeolite pellets caused improvement of mechanical strength of mortars. The highest flexural strength value ( 0.5 MPa) was achieved in both mortars with fine zeolites pellets at 90 days and 20 and 30 wt.% metakaolin, and coarse zeolite pellets at 180 days and 30 wt.% metakaolin as lime replacement. 1.0 MPa was the highest compressive strength value obtained at 180 days for mortars with both fine zeolite pellets and coarse zeolite pellets, with 20 and 30 wt.% of metakaolin, respectively. Elasticity modulus ranged from 2.3 GPa to 3.9 GPa confirming the high deformation capability of these mortars. Zeolite pellets type A is a promise synthetic material that could be successfully used in air lime– metakaolin render mortars for applications in the conservation and restoration of cultural heritage.

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Embora o excremento bovino (EB) seja um material utilizado há milênios pela humanidade na arquitetura vernácula, este estabilizante tem sido pouco investigado cientificamente. Neste estudo foi avaliado o efeito da adição de EB em argamassas de terra (terra + areia) produzidas com uma terra do Brasil (ITA) e duas terras de Portugal (CAP e MON). Para avaliar os efeitos da adição do EB, com cada uma das três terras foram produzidas e testadas argamassas: sendo uma de referência (0% EB), e mais duas com adição de EB nas seguintes proporções volumétricas 10% e 20% do volume total de terra + areia adicionada. Os ensaios de densidade e a produção dos corpos de prova foram realizados de acordo com a norma alemã DIN 18947, específica para avaliação de argamassas de terra para reboco sem adição de estabilizantes químicos. Para avaliação da durabilidade e resistência à água foi realizado o ensaio de imersão em água. O comportamento dos corpos de prova foi fotografado ao imergi-los e depois de 1, 2, 5, 10, 15 e 30 minutos imersos, e até aos 14 dias. A avaliação da integridade dos corpos de prova possibilitou analisar o efeito da adição do EB na argamassa de terra tropical e nas duas com terras ibéricas. As argamassas sem EB se desintegraram rapidamente nos primeiros 3minutos. A adição de EB aumentou visivelmente a durabilidade dos corpos de prova produzidos comtodas as terras avaliadas, sendo a adição de 20% EB mais eficiente em relação à de 10% EB. Valedestacar que a argamassa produzida com a terra MON e adição de 20% EB manteve sua forma intactapor 14 dias, quando as últimas observações foram realizadas. Assim, o EB demonstrou o seu potencialpara argamassas e rebocos de terra com as terras tropical e ibéricas testadas, justificando ser maisinvestigado como um bioestabilizante eficiente.

O excremento bovino é um material utilizado há milênios pela humanidade como estabilizante em técnicas de construção com terra, sendo comum até à atualidade em comunidades tradicionais no Brasil. No entanto, esta estabilização ainda é pouco estudada cientificamente. Neste estudo foi avaliado o efeito da adição de excremento bovino em argamassas produzidas com uma terra argilosa do Brasil e outra areno siltosa de Portugal. Os métodos e ensaios utilizados para esta avaliação são os descritos na norma alemã DIN 18947 para avaliação de argamassas de terra para reboco não estabilizadas com ligantes convencionais. Nas argamassas produzidas com as duas terras a adição resultou na redução da retração linear por secagem e no aumento das resistências à flexão, à compressão e da aderência por cisalhamento. Assim, o excremento bovino demonstrou ter efeitos positivos em argamassas de terra para reboco produzidas tanto com uma terra de clima tropical como com uma terra de clima temperado mediterrâneo, merecendo ser mais estudado como bioestabilizante eco-eficiente.

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The presence of iron sulfides in aggregates can be responsible for severe concrete degradation. The oxidation of these minerals in the presence of humidity can lead to the formation of sulfate minerals, such as gypsum, ettringite and thaumasite, from the reaction with the hydrated cement paste components, leading to expansion and cracking. A number of severe cases is known in Canada and in the USA.In the Iberian Peninsula, especially in the Catalan Pyrenees region, Spain, several concrete deterioration cases have been reported involving the use of aggregates with iron sulfide-bearing phases, namely pyrrhotite. The affected structures comprised buildings and public works, such as gravity dams and a deep study of the affected concrete and the reactions involved was performed, as documented in several papers and reports. The mechanism led to the settlement of a threshold of maximum total sulfur content of 0,1 % as S in aggregates in EN 12620, referring to special precaution when pyrrhotite is present in the aggregate. The identification of this mineral at the microscopic scale demands that polished surfaces or polished thin sections are prepared and the study is performed using reflected light microscope, and not the transmission light petrographic microscope applied in the identification of non-metallic minerals. The most common Portuguese aggregates are limestone and granitic rocks. The later usually contain opaque minerals and, therefore, for the most recent large dams built in the country with granitic aggregates the chemical analysis, including S, was performed. In some regions of the country, other rocks are used in the construction industry, namely schist, diorite and gabbro. The present work presents the state-of-art about the occurrence of pyrrhotite in Portugal and a research plan for successfully investigating the potential oxidation of aggregates containing this iron-sulfide phase.

Built heritage constitutes a legacy that is received from the past, experienced in the present, and that should be preserved for future generations. However, the succession of this legacy is sometimes lost because the structures have undergone successive conservation or rehabilitation interventions, often unknown or poorly documented throughout their lifetime. This lack of knowledge impacts the assets' performance and maintenance, especially according to the present guidelines for the full benefits of sustainable and resilient practices and solutions in a changing environment. Thus, for the safety, quality, durability, performance, sustainability, and adaptive capacity of built heritage, the identification, characterisation, and diagnosis of the conservation condition of the original materials are usually required.The assessment of the suitability of the new materials for the foreseen functions and the compatibility analysis of repairing materials with the existing ones is, as well, usually required for supporting design specifications, construction practices and procedures appropriate for the building elements to be repaired, preserved, or reused. Decision processes should also be based on solid knowledge of the characteristics and vulnerabilities of materials and products because their suitability to both environmental and operating conditions will primarily affect their performance.This paper aims to emphasise the usefulness of the information provided by nondestructive or semi-destructive microscopic and spectroscopic techniques for the characterisation and condition diagnosis of ancient materials. The examples included in this paper, taken from studies of ancient metallic bridges and metalwork in buildings, illustrate the significant differences in the characteristics of ferrous materials used in Portuguese built heritage. Furthermore, the valuable information gathered on the chemistry and microstructure of materials can be further related to the type of material and the expected mechanical properties. Therefore, the fitness of the original materials used or reused and the suitability of the existing construction practices and both new structural and protection materials can be inferred.

Os artigos que compõem esta edição foram criteriosamente selecionados e aprimorados, seguindo igual metodologia de trabalho do número anterior, contribuindo para compor um dossier temático de elevado interesse e qualidade. No seu conjunto, os vários textos sublinham o papel dos materiais históricos na construção multidimensional do território humanizado, ligando os aspetos tangíveis e intangíveis, transportando saber e gosto, tradição e inovação. Estes artigos, bem como os do primeiro volume, são também uma fonte reflexão e de conhecimento sobre alguns dos materiais de construção mais empregues no Património abrindo, nalguns casos, novas perspetivas para futuras investigações nesta área do conhecimento.

Vários

The use of gypsum plaster for the interior coating of walls and ceilings in the Portuguese architecture was particularly expressive in the period between the XVIII and the XX century. However, information about this important heritage is almost nonexistent, which is leading to a rapid loss of important patrimony. In this paper the results of the characterisation of five gypsum plaster samples from the second half of the XIX century belonging to the Arabian Room of the Bolsa Palace, located in Oporto, North of Portugal, are presented and discussed. XRD and TGA-DTA techniques were used to establish the mineralogical composition, and the relative proportions of the binders. Optical microscopy and FESEM-EDS observations were performed both in fractured and polished surfaces in order to determine the stratigraphy and the composition of individual layers. The results of this characterisation work showed that the plasters used were mainly composed of gypsum and hydrated lime in different proportions – a feature that was correlated with the application techniques of the decorative elements analyzed - and allowed the determining of the restoration interventions they had already been submitted to. Some physical properties like the dynamic modulus of elasticity and capillary absorption were also determined, and a correlation between the results obtained was established with previous studies performed by the authors.

The Santíssimo Sacramento Convent in the Alcântara quarter of Lisbon is one of the most important ecclesiastical structures of the Filipino Period (1580- 1640), showing an innovative architectural layout. An intervention aiming at the repair and restoration of the interior plasters of the Santíssimo Sacramento Church was performed in 2009 and 2010. To support the restoration plan, a physical, mechanical and chemical-mineralogical characterization of the internal plasters of the church was carried out. In this paper the main results are presented, such as various types of plasters, mortars, stuccos and pigments; and also the nature of the main anomalies were identified and characterized. The results obtained contributed to the identification of the main decorative programs characterized by the use of different materials and techniques. The mortars are in very good condition, being composed of aerial calcitic lime with quartzitic and basaltic aggregates. The stuccos are comprised by gypsum and non-hydraulic lime, while the decorative layers features lime with some precious pigments, such as ultramarine (lapislazzuli) and gold-foil gildings. The plaster conservation and restoration works were performed with compatible repair materials selected according to the physical-chemical characterization and on the evaluation of the conservation state.

A degradação de estruturas de betão por reacções expansivas internas é uma patologia que, não sendo relativamente recente a nível internacional, tem vindo a manifestar-se duma forma crescente nos últimos anos em Portugal. Esta patologia tem afectado vários tipos de estruturas de betão, algumas de grande importância estratégica, nomeadamente grandes barragens e obras de arte (pontes e viadutos). A título de exemplo referem-se os casos do Viaduto Duarte Pacheco, e as Barragens de Alto-Ceira e Santa Luzia, alguns dos quais obrigaram a intervenções de elevado custo. Esta forma de degradação, que engloba a reacção álcalis-sílica (RAS) e a reacção sulfática interna (RSI), quando ocorre numa estrutura é particularmente nefasta porque está relacionada com a formação de compostos expansivos que provocam a fissuração do betão, contribuindo decisivamente para a diminuição da vida útil da estrutura, podendo em alguns casos obrigar à sua demolição. Associada a esta situação, acresce o facto de não se dispor actualmente dum método totalmente eficiente e económico de combater esta forma de degradação. Deste modo, para garantir os tempos de vida útil preconizados para as novas construções devemse adoptar medidas preventivas para evitar ou minimizar os efeitos da ocorrência deste tipo de reacções expansivas nas estruturas de betão. Em Portugal, medidas preventivas destas reacções expansivas internas estão contidas na Especificação LNEC E 461, citada na NP EN 206-1 – Betão. Parte 1: Desempenho, especificação, produção e conformidade, a qual inclui a fixação de níveis de prevenção de acordo com a categoria de risco e exposição ambiental do elemento ou da estrutura de betão. Estas medidas passam por uma caracterização dos factores condicionantes destas reacções nos constituintes do betão e pela aplicação de medidas para a sua inibição. Neste particular, a utilização de adições minerais em substituição parcial do clínquer portland, é uma medida que além de diminuir o calor de hidratação, permite a redução da alcalinidade da solução intersticial do betão e contribui ainda para reduzir a quantidade de sulfatos no betão, evitando assim a formação de produtos expansivos. Actualmente é já conhecido que as adições minerais do tipo II, em substituição parcial do cimento no betão e em quantidade suficiente, podem mitigar os efeitos destas reacções. A acção destas adições minerais depende, no entanto, da sua composição e reactividade pozolânica.Apesar dos bons resultados já demonstrados por algumas adições, nomeadamente as cinzas volantes, o seu uso pode estar comprometido a curto/médio prazo, tendo em conta a cada vez maior preocupação, por parte da maioria dos Países, na utilização de renergias “limpas”. Esta tendência terá como consequência uma diminuiçãtt ou mesmo o esgotamento da produção de alguns subprodutos industriais. No caso dos produtos naturais, é previsível um agravamento das restrições ambientais associadas à sua exploração e tratamento. Foi neste contexto que se iniciou no LNEC, em colaboração com o Laboratoire Central des Ponts et Chaussées de Paris e as Universidades de Aveiro, Minho e Évora, um projecto de avaliação da utilização de novos materiais com características pozolânicas, capazes de responderem às necessidades da indústria do betão a curto/médio prazo. Este projecto, que contou com o apoio da Fundação para a Ciência e Tecnologia (Projecto PTDC/CTM/65243/2006 – EXREACT – Mitigação de reacções expansivas deletérias em estruturas de betão) visa ainda o aperfeiçoamento de metodologias de diagnóstico e prognóstico da ocorrência de reacções expansivas internas em estruturas de betão existentes. Os resultados do trabalho realizado no decorrer do projecto têm vindo a ser divulgados em artigos e comunicações em seminários nacionais e internacionais, mas também através duma página Web (http://www-ext.lnec.pt/EXREACT/index.html) e com a organização de reuniões como a do presente Workshop, que contou com o apoio do LNEC, da Comissão Organizadora do REABILITAR 2010 - Encontro Nacional de Conservação e Reabilitação de Estruturas e dos oradores convidados. Este Workshop visa apresentar os últimos desenvolvimentos sobre os aspectos da prevenção, modelação e reparação, proporcionando uma oportunidade para a compartilha de ideias e soluções para a gestão das estruturas afectadas por RAS e/ou RSI.

Though an important subject that has been investigated for several decades, the full understanding of the alkali release from aggregates, its contributing factors and role in the alkali-silica reaction still remains a challenge for the scientific community. Recently, the RILEM AAR-8 test method was developed and several improvements to thismethodology have already been proposed. In this paper, automated scanning mineralogy (QEMSCAN®) is introduced as a complementary tool for petrographic characterization in order to better understand thefactors contributing to the alkali release fromaggregateswith a similarmineralogy.Itwas used to examine distinctive textures, grain sizes and alteration of amylonite, a cataclasite, a gneiss, a granite and an altered granite. The QEMSCAN® analysis enabled a more thorough understanding of the aggregates whilst complimenting the optical petrography.

The most common standards ruling the assessment of the potential reactivity of aggregates consider that the petrographic analysis should be followed, in the first step, by accelerated mortar-bar tests and, in case of a positive result, by concrete-prism tests.However, experience has shown that these different approaches often provide contradictory results in the classification of an aggregate as innocuous or potentially reactive. Discussion about the inaccuracy of the accelerated mortar-bar test for some slow reactive aggregates has been puzzling the scientific community andsome explanations have been suggested to explain this fact.In the present work, deformed rocks used as aggregates, previously submitted to accelerated mortar-bar tests and to concrete-prism tests, are analyzed regarding different grain sizes. The research aims to define the role of crushing mechanisms in the destruction of crystals originated from sub-graining, due to tectonic deformation,during the production of the smaller particles requested by the mortar-bar test. With this purpose, the petrographic analysis of the rocks selected, and their correspondent sand size aggregates has been done using the image-based open software JMicrovision

In previous research, volcanic rocks from the Azores Islands (Portugal), Brazil, Canada, Canary Islands (Spain), Hawaiian Islands (USA), Iceland, Japan, Mozambique, New Zealand, Norway, and Turkey were studied to assess their potential reactivity to alkalis. The analyzed samples correspond to basalt, andesite and rhyolite. Several tests were performed, namely, petrographic characterization by optical microscopy and scanning electron microscopy, bulk rock chemical analysis, accelerated mortar-bar test and concrete prism test.In volcanic rocks, the possible reactive forms of silica are not only of minute size, and hard to identify, but are also usually present in very low content, and often below the detection limits used in chemical bulk rock analysis.This study reports the results obtained in additional tests to characterize the aforementioned aggregates: 1) the phosphoric acid method, by dissolution of silicates of the rock reduced to powder, preserving the free silica forms of the sample; and 2) the gel-pat test, applied on lengthwise slabs of concrete prisms preparedwiththe selected aggregates, to obtain the possible presence of reactive components, in particular volcanic glass and free silica polymorphs.The results from the two tests are presented and the possible correlations with the results from the petrographic characterization and from the expansion tests are discussed.

The growing interest in preserving the built heritage is a driving force towards the search for new rehabilitation solutions compatible with the original construction techniques of ancient buildings. For the design of an adequate reinforcement solution, it is necessary to know in detail the building to be rehabilitated, as well as its original constructive solutions and materials.This paper presents the results of an experimental campaign on samples of air lime-based laying and coating mortars, extracted from an old masonry building in the historic center of Lisbon, built in 1910, during the rehabilitation works. The different parameters analyzed allow for the composition characterization and evaluation of their mechanical, physical and chemical properties. Based on this characterization, the influence of these mortars on the overall behavior of load-bearing walls of buildings belonging to the typology under study is also evaluated.Considering the results obtained in the characterization tests for the mortars in study, it was verified that the binder used in both mortars was air lime. The values for compressive strength, modulus of elasticity and the curves obtained in the capillarity and drying tests, are also compatible with this type of mortars. It was determined that the mortars are similar in terms of physical and mechanical characteristics, to Portuguese mortars studied in current buildings of the same historical period. This type of information is crucial in a structural analysis and allows to identify materials compatible with the original ones that can be used in rehabilitation interventions.

Cementitious materials have a considerable global warming footprint. This is due mainly tothe cement incorporated. For a tonne of cement produced other 800 kg of CO2 [1] are releasedinto the atmosphere.According to the European Sustainable Development Goals, cement industry should becomecarbon neutral by 2050. To meet this goal, the European Cement Association (Cembureau)developed a Roadmap with specific guidelines by 2050 based on five approaches (5C). Thefirst four are focused on improvements in clinker production, cement formulation,construction processes and concrete formulations. The last 5C is re-carbonation of thecementitious materials.This research investigates the CO2 absorption capability of recycled aggregates (RA) fromconstruction and demolition wastes (CDW), when submitted to a forced carbonation. It isknown that CDW still have some potential to CO2 capture, which is a long-term and securecarbon storage. For that purpose, several CDW were collected from recycling plants, fromselective demolitions and from concrete plants.It was concluded that RA when submitted to forced carbonation absorb between 47 to 315 kgof CO2 per tonne of cement paste, which has a potential to meet the re-carbonation targetsestablished by the roadmaps to carbon neutrality.

The Mirante da Quinta da Azeda, in Setúbal (Portugal), is a peculiar observation tower built in the early 20th century, and one of the first examples in which reinforced concrete was applied in Portugal. It has an unusual architectural configuration, displaying elements of great slenderness. In the scope of the CemRestore research project - Mortars for the conservation of early 20th century buildings: compatibility and sustainability, several mortar and concrete samples were collected from this structure and were characterized using a combination of mineralogical, microstructural, physical, and mechanical techniques, including XRD, petrography, SEM-EDS, open porosity, capillarity coefficient, compressive strength, and ultrasonic pulse testing. In this paper, the main characterization results are presented and discussed. The results show that all structural and decorative samples are made with Portland cement, while one rendering mortar is lime-based. The sand is mostly siliceous whereas pebbles and crushed limestone can be found as coarse aggregates in concrete samples. This characterization allows for broadening the scientific knowledge about the materials of that period used in Portugal, also enabling the establishment of the requirements to be met by mortars and concrete to be used in the repair of this distinct structure.

Earth mortars and gypsum mortars present ecological advantages compared to mortars made with other common binders. When applied as plasters, they are also referred as having advantages in improving comfort and indoor air quality. For earth plasters, this improvement is associated with the hygroscopic capacity of the clay minerals, which promotes high sorption and desorption capacity of water vapor. So, earth plasters can contribute to the regulation of the indoor relative humidity. Another important advantage of plasters could be their ability to capture carbon dioxide (CO2). In the present study, the sorption and desorption performance, and the capacity to capture CO2 by earth and gypsum plasters are evaluated. It is confirmed that the earth plaster has the greatest sorption and desorption capacity, but also higher CO2 capture capacity than gypsum plaster. This confirmation opens new perspectives for the use of functionalized plasters that guarantee greater control of air quality inside buildings.

Coimbra apresenta um elevado valor arquitetónico demonstrado pelos 36 imóveis, conjuntos ou sítios (22 monumentos nacionais e 14 imóveis de interesse público) actualmente classificados (DGPC, 2015) sendo a maioria deles localizados no Centro Histórico de Coimbra (CHC) e zona alta da cidade. No âmbito do projecto POCI/HEC/60371/2004 ‘Bases para o restauro dos revestimentos históricos do Centro Histórico de Coimbra’, foi feito um levantamento das existências cromáticas existentes no CHC-Alta (zona de edifícios de habitação da Alta de Coimbra, Figura 3.1), a partir do qual se seleccionaram edifícios que ainda apresentavam vestígios de pinturas em várias camadas, o mais antigas possível.

Os revestimentos híbridos nanoestruturados apresentam um elevado potencial no âmbito da protecção anticorrosiva dos metais, prevendo-se que no futuro estes revestimentos possam, não só substituir os tratamentos à base de crómio usados na indústria do tratamento de superfícies metálicas para protecção anticorrosiva, como também evoluir para sistemas integrados multifuncionais que dispensem o pré-tratamento e sejam mais “amigos” do ambiente. O processo sol-gel usado para a obtenção destes revestimentos permite, através da combinação de diferentes precursores e da manipulação das condições de síntese “desenhar” e optimizar a estrutura química e a funcionalidade dos revestimentos nanoestruturados com o objectivo de obter as propriedades desejadas para uma determinada aplicação. O estudo apresentado no presente trabalho teve como objectivo principal a optimização de revestimentos híbridos nanoestruturados obtidos pelo processo sol-gel para a protecção anticorrosiva de uma liga de alumínio frequentemente utilizada na construção civil. Para alcançar este objectivo foram preparados diversos revestimentos híbridos nanoestruturados e aplicados na liga de alumínio EN AW-6063, cujo processo de síntese foi optimizado variando parâmetros como a composição, processo de cura e condições reaccionais sol-gel, visando a obtenção de revestimentos com propriedades anticorrosivas melhoradas. Posteriormente, foi feita uma avaliação do comportamento à corrosão dos revestimentos optimizados em diferentes condições corrosivas, individualmente e como parte integrante de um sistema de protecção anticorrosiva usualmente aplicado em ligas de alumínio para fins arquitecturais. No presente documento é apresentada uma revisão bibliográfica da aplicação deste tipo de revestimentos na protecção anticorrosiva, seguindo-se a descrição detalhada dos procedimentos experimentais do estudo, nomeadamente, os materiais e os procedimentos para obtenção e caracterização dos revestimentos estudados, a apresentação dos resultados obtidos no decurso do desenvolvimento experimental realizado, sua interpretação, discussão e as conclusões parciais mais relevantes. No final, resumem-se as principais conclusões obtidas no estudo e faz-se uma avaliação global da aplicabilidade dos revestimentos optimizados na protecção anticorrosiva de ligas de alumínio no âmbito da construção civil, e indicam-se necessidades de desenvolvimentos futuros.

Nesta dissertação, estudou-se o comportamento electroquímico de cinco ligas austeníticas de aço inoxidável em meio alcalino, nomeadamente duas ligas de Fe-Cr-Ni (1.4301?SS0 e 1.4436?SS4) e três novas ligas de elevado teor em manganês Fe-Cr-Mn (SS1, SS2 e SS3). Os estudos incidiram na avaliação da resistência à corrosão das ligas, em soluções alcalinas e no betão, e na caracterização das propriedades dos filmes de passivação sob influências várias, designadamente, condições de estabilização (electrólito, tempo e potencial de formação do filme), composição e microestrutura das ligas, soldadura e estado da superfície do aço. O estudo da capacidade diferencial em função do potencial mostra o comportamento dos filmes de passivação como semicondutores tipo-n e tipo-p, respectivamente, para valores anódicos e catódicos relativamente aos potenciais de banda plana, possibilitando a determinação das suas propriedades electrónicas. Estas traduzem as principais diferenças dos dois grupos de ligas, sendo que as ligas de Fe-Cr-Mn mostram uma menor razão da densidade de aceitadores com a densidade total de portadores de carga, do que as ligas de Fe-Cr-Ni, e um nível de doadores profundo, cuja ionização depende do potencial aplicado. Todas as ligas revelaram uma elevada resistência à corrosão nos diferentes meios, sendo a sua estabilidade especialmente dependente do acabamento superficial do aço e da existência de condições que promovam a corrosão intersticial. A soldadura das ligas induziu a formação de picadas instáveis, cuja repassivação foi desfavorecida em duas das ligas de Fe-Cr-Mn (SS1 e SS3). A presença de fissuras no betão demonstrou a despassivação das ligas e a susceptibilidade à corrosão sob tensão da liga SS1 no betão. As propriedades dos filmes de passivação, nomeadamente as densidades dos portadores de carga, que podem ser correlacionadas com a composição e a microestrutura das ligas, justificam as diferenças no comportamento electroquímico das ligas de Fe-Cr-Ni e de Fe-Cr-Mn. Para além das diferenças promovidas pelos teores de níquel e de manganês e pela ferrite, a maior resistência à corrosão das ligas SS2 e SS4, respectivamente, quando comparadas com as restantes ligas de Fe-Cr-Ni (SS0) e Fe-Cr-Mn (SS1 e SS3), é devida à presença do molibdénio e seus eventuais efeitos sinergéticos com o crómio e azoto.

O estudo da composição de argamassas antigas, que implica usualmente a utilização de técnicas de caracterização físico-química, mineralógica e microestrutural, desempenha um papel fundamental para a preservação do património cultural, permitindo obter um conhecimento bastante profundo sobre os seus constituintes e revelando detalhes importantes sobre as técnicas de construção, eventuais reparações e o estado de conservação e desempenho das mesmas. Neste trabalho foram analisadas argamassas provenientes de quatro edifícios religiosos da região do Alentejo, nomeadamente a Sé Catedral de Évora (Séc. XIII-XVII), a Igreja de Nossa Senhora da Assunção em Elvas (Séc. XVI), a Igreja Matriz de Mértola (Séc. XII) e o Conjunto Monumental de Amieira do Tejo (Séc. XIV-XVI). A metodologia de caracterização empregue recorreu a diversas técnicas, nomeadamente difracção de raios X (DRX), análise termogravimétrica (ATG), microscopia óptica (MO), microscopia electrónica de varrimento acoplada a espectroscopia de raios X por dispersão de energias (MEV-EDS), espectrofotometria de absorção atómica (EAA), potenciometria, gravimetria, sorção de água por capilaridade, resistência mecânica, porosimetria de mercúrio e a adsorção de azoto a – 196 ºC. A aplicação da metodologia proposta permitiu determinar a composição e o estado de conservação das diversas argamassas, tendo-se constatado que nas argamassas da Sé Catedral de Évora e da antiga Sé de Elvas foram utilizados dois tipos de ligantes aéreos, cal calcítica e cal dolomítica, sendo o primeiro tipo o predominante. Nos casos de estudo da Igreja Matriz de Mértola e do Conjunto Monumental de Amieira do Tejo, as argamassas apresentam um ligante essencialmente calcítico. Verificou-se que os agregados utilizados são correlacionáveis com a litologia local de cada caso de estudo. As argamassas apresentam diferentes proporções de agregado, e nos casos de estudo da Sé Catedral de Évora, antiga Sé de Elvas e Igreja Matriz de Mértola foram utilizados fragmentos cerâmicos como aditivos.

Os fenómenos de instabilidade de taludes são frequentemente causa de acidentes humanos e materiais constituindo por esse motivo um problema geotécnico de maior importância. Os estudos dos movimentos de terra, são relativamente morosos e complexos, uma vez que é necessário ter em atenção muitos factores, quer relacionados com características internas ao maciço, ou seja, características geológicas e geotécnicas, quer com acções externas. Os estudos das instabilidades de taludes ou vertentes naturais, têm como objectivo avaliar avaliar a perigosidade associada à sua ocorrência, os correspondentes riscos e definir medidas de prevenção e de controlo dos movimentos de terra que possam ocorrer. As modificações geológicas e climáticas experimentadas ao longo do tempo geram uma modificação constante na geometria dos taludes devido à sua sucessiva adaptação a novas condições de equilíbrio. Geralmente, as áreas mais propícias à ocorrência deste tipo de movimentos, correspondem a zonas montanhosas, escarpadas e sujeitas a elevada precipitação ou a condições hidrogeológicas desfavoráveis. Deste modo, a presente dissertação tem por objectivo fazer uma abordagem da problemática associada à instabilidade de taludes em rochas silto-argilosas, dando uma panorâmica das técnicas de engenharia usadas para o controlo dessas situações e salientando-se algumas técnicas de biorremediação apropriadas para o controlo de movimentos superficiais. Os temas abordados são explicados com uma aplicação a um caso real de estudo em Portugal.

Neste relatório, após uma introdução em que se resumem as características do titânio e das suas ligas mais relevantes para a aplicação como material de construção e se apresentam aplicações destes materiais na construção civil, apresentam-se resultados de um trabalho experimental preliminar desenvolvido com o objectivo de estudar a corrosão galvânica de aço inoxidável quando associado a titânio, em meio alcalino, a várias temperaturas.

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The organic-inorganic hybrid sol-gel films have been reported as an effective anti-corrosion and environmentally friendly alternative to Cr(VI) pre-treatment for aluminium alloys. These hybrid materials, constituted by nanostructured polymer networks, interconnecting organic and inorganic materials, are of interest because the synergic effect on the mechanical and chemical properties achieved. The organic components impart flexibility, density and functional compatibility with organic coatings, while inorganic components impart hardness, resistance to abrasion and improve adhesion to the metal substrate. The sol-gel process used to obtain these coatings, through a series of simultaneous hydrolysis and condensations reactions between alkoxide precursors, yields highly adherent, chemically inert films on metal substrates and allows the variation of the different synthesis parameters to achieve coatings with optimized properties. In this work, hybrid films were synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors, using different amounts of TPOZ (10%, 20%, 30%) and applied to EN AW-6063 alloy by dip-coating, aiming to achieve the best anticorrosive coating. The corrosion behaviour of aluminium specimens coated with these films was evaluated by Electrochemical Impedance Spectroscopy (EIS) in 0.5 M NaCl solution for 63 days. The results obtained revealed that the hybrid films provided effective corrosion protection, exhibiting good barrier properties, however, it was found that 30% of TPOZ led to a marked decrease in the barrier properties with time. The hybrid films prepared were also characterized by Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), Infrared Spectroscopy and Thermogravimetric Analysis (TGA-DTG) in order to relate their morphology and chemical structure with the corrosion behaviour.

The general designation of “internal expansive reactions” includes the alkali-silica reaction (ASR) and the internal sulfate attack by delayed ettringite formation (DEF). These reactions are characterized by the formation of expansive compounds in hardened concrete and consequent cracking of the structure. In Portugal, the number of structures, mainly dams and bridges, affected by ASR is very significant and in some cases require considerable investment in rehabilitation interventions. Moreover, previous research has shown that the use of some aggregates, initially regarded as inert, can cause problems, proving the need for further insight on the role of aggregates and prevent the occurrence of ASR in constructions. The economic value of various types of structures (e.g. dams, bridges, airfields) and the high costs related to structural degradation including losses of functionality and the permanent or temporary unavailability (for repair and rehabilitation) could be an important overthrow. Thus thorough understanding of the earth materials requirements for concrete manufacture are of vital economic importance in view of the prevention of deterioration and aging of structures whose longevity and functionality must be guaranteed. It is imperative to provide the concrete producers with the necessary knowledge in order to avoid this type of concrete degradation. Particularly important is the recently approved Lisbon-Madrid High Speed Train railway construction. This expensive operation will require large quantities of aggregates for the construction of bridges and other concrete infrastructures. Three main sources of raw materials will be considered for the study: St. Eulalia, Montemor and Cano. These quarries are already major exploitation sites separated by 50 km and not far from the future High Speed Train railway. Two of them are granitoid rocks but the raw material from St. Eulalia is richer in quartz and poorer in ferromagnesian minerals than the Montemor aggregates. The enrichment in calcium of feldspar goes together with the iron and the magnesium. The Cano aggregates are very different materials. The main lithology is a dolomite rock with local microscopic enrichments in phyllosilicates and very deformed quartz. Mineralogical and textural characterization of the aggregates was done by optical microscopy. The crystallinity of quartz was also evaluated by XRD and FTIR. The aggregates were also studied by accelerated expansion mortar-bar and concrete-prism tests to evaluate their potentially alkali-reactivity. The relationship between aggregates characteristics and their behaviour in what concerns to alkali reactivity will be discussed.