Publications

Mortars are among the most important materials in building construction. They aregenerally obtained by mixing aggregates with an inorganic binder. The identification of mortar constituents,particularly the binder type in historic buildings, is one of the essential aspects of buildingconservation, considering that the new conservation materials must be chemically, mechanically,and physically compatible with the old masonries. Among other techniques used to characterisebinders, those related to optical and electronic microscopy are particularly important. Microscopyand combined techniques may be the key to this identification since the classic mineralogical andchemical-based identification approaches are not conclusive enough in investigating the types ofhydraulic binders in mortars. This work presents an analysis procedure to identify mortar binders bycombining EDS microanalysis and petrography. Mortar samples of known composition were usedas a reference for analyzing mortars from historic buildings. The proposed methodology made itpossible to identify the type of binder or a mixture of binders based on the identification of the binderfeatures by petrography together with analysis of the chemical composition of the paste by X-raymicroanalysis under a scanning electron microscope.

Carbon fiber reinforced polymer (CFRP) composites have shown desirable properties in aerospace, automotive,and construction industries. Focusing on the latter and in the context of strengthening existing structures, CFRPcomposites are typically bonded to concrete structures using epoxy adhesive as a bonding agent. To date, there isa lack of literature on the durability of both the CFRP composite and epoxy adhesive. In this regard, the durabilityof two different commercially available CFRP laminates and epoxy adhesives was assessed after exposure todifferent indoor and outdoor environments for up to 4 years. Experimental, numerical, and analytical studieswere conducted. In the latter, a new formulation was introduced to model water diffusion through the epoxyadhesive. The results from the experimental tests showed that water immersion substantially affected the twostudied epoxy adhesives, resulting in a reduction of approximately 60

Application of carbon fibre reinforced polymer (CFRP) composites in strengthening of existing reinforced concrete(RC) structures has been widely accepted. However, the durability of adhesively bonded CFRP-concretejoint has not yet been fully investigated, which therefore paves the way to the topic addressed in this work:the durability of the joint in concrete elements strengthened with CFRP laminate using externally bondedreinforcement (EBR) technique. Concrete strengthened elements were kept in laboratory-controlled environments(approximately 20

Fibre-reinforced polymer (FRP) composites have gained popularity in civil structural applications due to their advantages over traditional materials. Despite their proven better performance in harsh conditions, FRP composites are susceptible to degradation due to various environmental agents; moreover, the lack of durability data for relatively thick laminates produced by pultrusion is a concern. To address this, in the scope of the Durable-FRP project, an extensive experimental program was conducted to assess the durability of thick FRP laminates produced by pultrusion, consisting of glass fibres and unsaturated polyester and vinyl ester resin matrices, subjected to accelerated laboratory ageing and in-situ natural weathering. This paper presents preliminary results from durability tests on such glass-FRP (GFRP) laminates under particular thermal ageing environments, including constant temperatures of -15 °C, 20 °C, 40 °C, and 60 °C for a period over 12 months, as well as 100 and 200 thermal cycles between 15 °C and 60 °C. Following environmental exposure, the degradation of mechanical properties was evaluated using various tests, including tension (in both longitudinal and transverse directions), compression, flexure, in-plane shear, and interlaminar shear. In general, minor mechanical degradation was observed, except in terms of transverse tensile strength (resin-dominated) following constant exposure to extreme temperatures, with minimum property retentions of 74% and 83% at -15 °C, for vinyl ester and unsaturated polyester matrices, respectively.

The aim of the present study is to assess if recycled gypsum from plasterboard waste can be added to earth plastering mortars instead of raw calcium sulphate hemihydrate when a mineral binder addition is foreseen to improve durability. Earth mortars with additions of 0 %, 5 %, 10 % and 20 % vol. of raw hemihydrate, gypsum milled from plasterboards with and without thermal treatment were produced and tested. In general, the additions led to an overall improvement in mechanical strength and resistance to water and did not significantly influence the hygroscopicity of the earth plaster. In general, earth mortars with untreated gypsum waste achieved comparable to superior results compared to mortars with treated gypsum waste, indicating the viability of using recycled gypsum from plasterboard without thermal treatment as earthen plaster addition.

Earth plasters have several advantages. Nevertheless, they are vulnerable when in contact with liquid water. For that reason, they have low durability when applied as an outdoor coating or in indoor areas with potential contact with water. In this study, the influence of six different surface treatments (traditional and innovative, based on raw materials and on waste) applied on a pre-mixed earth plaster, applied by a roller (r) or as a spray (s), was assessed. The treatments were: limewash (L), beeswax (BW), linseed oil (LO), graphene oxide dispersion (GO), water from paper immersion (WP) and water from gypsum plasterboard paper immersion (WPG). The application of L, BW and LO, despite the color change, improved the water resistance and the surface performance of the earth plaster (less than 80%

Carbon fiber reinforced polymer (CFRP) composites can be used to strengthen existing reinforced concrete (RC) structures. The CFRP laminate can be bonded to RC structure using epoxy adhesive via near-surface mounted (NSM) strengthening technique. However, existing literature generally lacks data about durability of NSM CFRPto- concrete bond. In this study, strengthened concrete elements were exposed to laboratory-controlled environments (at approximately 20

This paper defines a conversion factor included in the European technical specification for the design of fibre

This paper presents an experimental study about the synergistic effects between different exposure environments, likely to be found in civil engineering applications, and sustained flexural loading on the durability of pultruded glass fibre reinforced polymer (GFRP) profiles. Two off-theshelf GFRP profiles, comprising E-glass fibres and vinyl ester or unsaturated polyester resins, were subjected to sustained bending at service load levels corresponding to 10% and 20% of their flexural capacity; simultaneously, the profiles were exposed to the following three ageing environments, for periods of up to two years: (i) outdoor environmental exposure in a mild Mediterranean climate; (ii) hygrothermal exposure by continuous condensation at 20 (±2)

This paper addresses the study of renders and plasters

In the last years some concrete bridges in Portugal have shown premature deterioration due to intensive concrete cracking development mainly attributed to internal expansive reactions. An important experimental program was conducted by Laboratório Nacional de Engenharia Civil (LNEC), a public institution of the Portuguese Ministry for Public Works, Transports and Housing, in order to diagnose the causes and also prognostic the long-term behaviour of the deteriorated concrete bridges. The research conducted has pointeded that the concrete cracking was mainly due to the occurrence of internal expansive reactions: alkali-silica reaction (ASR) and/ or delayed ettringite formation (DEF). The ASR was caused by the use of alkali reactive aggregates and the DEF by the high heat-curing temperature obtained during the setting and hardening in combination with the high portland cement content used in the concrete mix designs. Residual expansion tests were done in order to access the residual ASR and DEF reactivity. Measurements have been carried out with the methods normally used for ASR and DEF concrete testing: 38º C ± 2º C and 95% HR in the first case and 20º± 2º C and 100% HR for the second. Mostly of the bridges show residual capacity to continue the expansion due to ASR or DEF, which forced remedial measures against these expansive reactions, mainly associated with control of the ingress of water into concrete. This situation in Portugal led to conclude that new deterioration cases can occur. To avoid these causes of damage the design and construction of new structures must follow the new Portuguese preventive methodologies (developed by LNEC).

Since there is a possibility of incorporating recycled aggregates (RA) as a complement to primary aggregates (PA) in concrete production, taking advantage of construction and demolition waste, there are some questions on the durability of concrete with recycled aggregates (CRA) that need to be answered. The durability of concrete with primary aggregates only (CPA) is conditioned, among other factors, by its degradation due to alkali-silica reactions (ASR). Since the first cases of ASR in CPA were identified, this expansive reaction has been a research theme resulting in the development of prevention and mitigation methodologies and in the comprehension of the chemical reactions involved. The present paper proposes to describe the current development of a research program on ASR in CRA based on an experimental campaign involving the production of CRA with different replacement ratios of coarse PA with coarse concrete RA, the use of different cement classes, and variations on the concrete curing conditions and on the reactivity of the mixes.

Le Laboratoire central des ponts et chaussées associé au réseau des Laboratoires des ponts et chaussées ainsi qu'à des partenaires extérieurs ont réalisé dans le cadre de l'opération de recherche « bétons environnementaux» des travaux visant à introduire cette problématique pour la formulation des bétons. Une réflexion sur les modalités d'application des méthodes ACV pour l'évaluation de l'impact environnemental des bétons a été menée. Un document de synthèse précise le contexte dans lequel un constituant alternatif d'un béton peut être développé et validé. En complément au volet méthodologique, le programme de recherche comporte un volet expérimental important comprenant notamment des travaux exploratoires sur des constituants alternatifs susceptibles de contribuer à la diminution de l'impact environnemental des bétons et dont le processus de développement est plus ou moins abouti. Cette journée de synthèse a pour objectif de présenter les principaux résultats obtenus. Elle s'articulera autour de 4 sessions : évaluation de l'impact environnemental d'un béton ; développement de matériaux alternatifs ; valorisation de sous-produits et recyclage ; des bétons environnementaux- application in situ.

Estudo por espectroscopia de impedância electroquímica das propriedades anti corrosivas de um revestimento híbrido (orgânico-inorgânico)obtido pelo processo sol-gel em função da quantidade de água de hidrólise adicionada.

La réaction sulfatique interne (RSI) est une cause de désordres susceptibles d'endommager assez sévèrement des ouvrages en béton. Les premiers cas sont apparus à l'Allemagne à partir de 1987 dans certaines pièces préfabriquées qui avaient été soumises à un traitement thermique inadapté à la formulation du béton. En France, les désordres ont été observés à partir de 1997 sur des ponts dont le béton avait été coulé en place et concernent aujourd'hui environ une soixantaine de structures. Il s'agit essentiellement de parties d'ouvrages massives (piles, chevêtre sur pile, …), mais aussi de quelques éléments préfabriqués, en contact avec l'eau ou soumises à une humidité.Le Laboratoire central des ponts et chaussées associé au Réseau des laboratoires des ponts et chaussées ainsi qu'à des partenaires extérieurs mènent depuis 2005 des recherches sur cette problématique afin de mieux connaître les moyens nécessaires pour concevoir des ouvrages exempts de RSI et de mieux gérer les ouvrages malades. L'objectif de cette journée est de présenter les dernières avancées ainsi que les nouvelles méthodes et guides techniques du LCPC.

The degradation of concrete structures caused by internal sulphate reaction, with delayed etringite formation (DEF) and alkali-silica reaction (ASR) is a problem that affects many concrete structures worldwide (Divet et al., 2004). When these reactions occur their effects are particularly dangerous since their reaction products are extremely expansive causing the cracking of the concrete, contributing for a large reduction in the lifetime of the structure and in some extreme cases forcing its demolition. Hence, there is an urgent need to find preventive methods that may inhibit such reactions in new concrete structures. Today, it’s well known that the use of supplementary cementicious materials, e.g. type II mineral additions, could sustain this degradation form. Moreover, their effect depends on the chemical and mineralogical composition and also the cement content replacement. This paper presents the findings of a long-term study (Santos Silva et al., 2006; Divet et al., 2006) on the expansion rate and microstructure of concretes with different amounts of mineral additions, like fly ash, metakaolin, ground granulated blast-furnace slag, silica fume and limestone filler. For this purpose different concrete compositions were produced by using the same cement type (CEM I 42.5R) and water/cement (w/c) ratio. The results of the blended-concrete compositions were compared with those of control compositions, and the conclusions were extracted

Os danos causados pelas reacções expansivas de origem interna (REOI), que envolvem a reacção álcalis-sílica (RAS) e a reacção sulfática interna (RSI), assumem grande importância na durabilidade e desempenho das estruturas de betão. Estas reacções afectam várias estruturas em todo o mundo, sendo necessário encontrar formas de prevenir/inibir a ocorrência das REOI nas novas estruturas de betão. Este trabalho pretende avaliar o efeito da utilização de lamas residuais de uma mina de tungsténio na mitigação das reacções expansivas de origem interna (REOI). Para este efeito, foram fabricadas diferentes composições de argamassas, utilizando-se um cimento CEM I 42,5R, um agregado silicioso reactivo e diferentes teores de lamas residuais em substituição do cimento portland. Neste artigo apresentam-se os resultados de ensaios de expansibilidade aos álcalis e de evolução da microestrutura das argamassas estudadas. Os resultados obtidos apontam para que uma substituição de pelo menos 30% de cimento portland por lamas residuais seja eficaz na mitigação das RAS.

As adições minerais têm mostrado resultados contraditórios na mitigação das reacções expansivas de origem interna. No LNEC, e com co-financiamento do projecto FCT EXREACT, estão em curso estudos a longo prazo que visam o estudo e a aplicabilidade destes materiais na mitigação das reacções expansivas de origem interna.

The Santissimo Sacramento Convent, in Alcântara quarter, in Lisbon, was an innovative architectural project in the XVII century and one of the most important ecclesiastic structures at that period in Lisbon. An intervention aiming at the restoration of the monument’s interior plasters was planned in 2009 and is presently being carried out. In this article the main results obtained in the physico-chemical characterization of the internal plasters from Santissimo Sacramento church in Lisbon are presented, including mortars, stuccos and pigments; the diagnosis methodology was applied for the evaluation of the state of conservation of the renders and the recommendations made for the repair mortars. The results obtained lead to the conclusion that the mortars are in very good condition, being composed by aerial calcitic lime with siliceous and basaltic aggregates, while the stuccos are constituted by gypsum and aerial calcitic lime and the decorative layers are of lime with some precious pigments too, such as ultramarine (lapislazzuli) and gildings.

As reacções expansivas de origem interna (REOI) no betão, em particular a reacção álcalis-sílica (RAS) e reacção sulfática interna (RSI), são particularmente perigosas já que os seus produtos são extremamente expansivos, o que origina a fissuração do betão contribuindo para a redução da vida útil das estruturas, podendo em casos extremos levar à sua demolição. Acresce que a detecção das REOI é difícil, necessitando de meios de diagnóstico que exigem elevada especialização. Igualmente problemática é a reparação das estruturas afectadas, que além dos elevados custos, acarreta um elevado risco de insucesso. É neste contexto que a mitigação das REOI se torna necessário, nomeadamente com a avaliação dos seus condicionalismos e dos materiais susceptíveis a este tipo de reacções. Particularmente importante é o estudo da influência de diferentes tipos de adições minerais como forma de evitar a ocorrência futura das REOI. Em Portugal, para além das cinzas volantes e metacaulino na RAS e RSI, pouco se conhece sobre a influência de outros tipos de adições minerais na mitigação das REOI. Já as adições do tipo I, nomeadamente o fíler calcário, suscitam dúvidas quanto à sua eficácia. Esta comunicação tem como objectivo dar a conhecer os resultados dum estudo em curso no Laboratório Nacional de Engenharia Civil (LNEC) sobre o efeito a médio/longo prazo das adições minerais na inibição das REOI. São discutidos os resultados referentes a ensaios de expansão e da evolução da microestrutura de betões fabricados com diversos tipos de adições minerais e teores de substituição.

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.