Publications

The concrete degradation caused by internal expansive reaction (IER) is a problem that affects many structures in the world. These reactions, which include the alkali-silica reaction (ASR)and the internal sulphate reaction (ISR) related with delayed ettringite formation, are very dangerous, due the expansive behavior of products formed, that cause the cracking of concrete. So it is urgent to find preventive methods to avoid or mitigate the onset of these reactions in new structures. This work aims to show the applicability of sludge from a tungsten mine in the mitigation of the IER. To evaluate the effect of sludge in the mitigation of ASR and ISR, mortar and concrete mixes were produced with 30% (%in mass) of cement replacement. The results obtained so far allow stating that tungsten mine sludge as Portland cement replacement could be effective in the ASR and ISR mitigation.

Metakaolin (MK) is nowadays a well-known pozzolanic material used in cement-based materials. Its benefits are related to its great pozzolanic reactivity when compared with some others pozzolanic materials, like fly ash or ground-granulated blast furnace slag. When MK reacts with calcium hydroxide, cementitious products are formed. It is known that the main phases produced during its pozzolanic reaction at ambient temperature are calcium silicate hydrates (CSH), stratlingite (C2ASH8) and calcium aluminate hydrate (C4AH13). However, in literature there are several discrepancies regarding these phases stability, namely the transformation of stratlingite and C4AH13 into hydrogarnet (C3AH6) at long term. The consequences of that instability are a reduction in the porosity and a loss of microstructural strength that can induce a complete material degradation. The MK is a material with great potential in Portugal, since there is a large abundance of kaolinitic clays, however its development is not yet achieved. In order to answer this demand a research project was initiated with the aim of optimizing the production of MK in Portugal and enhancing the durability of aerial calcitic lime mortars, to be mainly used in conservation and restoration of historical buildings. With the objective of studying the compounds formed in lime/MK and their stability during time, we have prepared different lime/MK ratio pastes (molar ratios). These lime/MK pastes were stored at saturated conditions (RH > 95%) and 23 ± 2 ºC temperature being analysed at several ages by TGA-DTA, XRD and SEM-EDS. In this paper the results obtained are presented and discussed.

Red mud (RM) is a solid waste derived from processing bauxite ore to produce alumina and is considered a hazardous waste due to its high pH. This paper describes the use of untreated mud and after calcination at distinct temperatures (450, 650, and 1000 °C) to attempt to improve its reactivity in cement mortars. In the formulations, portland cement was replaced with up to 30 wt% red mud, and the addition of the red mud changed the hydration process, setting time, and workability. The temperature of hydration increased as more RM was added, particularly when calcined in the interval of 450–650 °C. In these conditions, the hydration process was accelerated, and the workability decreased. These findings indicate that the presence of red mud significantly altered important properties of portland cement.

This work is inserted in a wider project aiming at the conservation and durability of historical renders, through compatibles techniques and materials; in particular the restitution of cohesion of historical renders, turned friable by the loss of binder due to physical or chemical actions, is studied. Surface consolidation, directed to restore cohesion and stability, is based on the use of materials with aggregating properties. This operation is reached usually through the application of organic or mineral consolidants, but inorganic consolidants (such as calcium hydroxide or ethyl silicate) are preferred due to better compatibility and durability. Based on the results of previous studies, two mineral compatible products were selected: a commercial suspension of nanoparticles of calcium hydroxide in propanol (Nanorestore); a silicate product, consisting on a limewater dispersion of ethyl silicate. Consolidation products were than applied on different mortars samples previously prepared, in order to assess their efficacy by determining their physical, mechanical and microstructural properties before and after the consolidation treatment. Mechanical and physical analyses were performed, such as compression and flexural strenght and superficial hardness. Microstructural and chemical analyses of the consolidation product and of the consolidated samples are also reported.

This study is focused on the electrochemical behavior and surface analysis of an eco-friendly organic–inorganic hybrid (OIH) coating for hot dip galvanized steel (HDGS) in contact with cementitious media. This treatment is a proposed alternative to replace toxic Cr(VI)-based pre-treatments used to control reactions between the zinc and wet concrete. HDGS samples were coated with two different sets of OIH gels obtained by a sol-gel process using a dip-coating method. Five distinct OIH matrices were obtained by reaction of functionalized metal-alkoxide (3-isocyanatopropyltriethoxysilane) with five different molecular weight diamine-alkylethers. One set of HDGS samples was coated with each of the five pure OIH matrices and another was coated with similar matrices doped with Cr(III). The morphology of OIH coatings over HDGS surface was characterized by SEM/EDS. Similar films were prepared separately and the respective resistivity was measured by electrochemical impedance spectroscopy. Polarization resistance and macrocell current density were used to evaluate the corrosion protection properties of the HDGS coated samples in contact with cementitious media for a period of 74 days. Results showed that the produced coatings provide barrier properties that withstand the high pH of the electrolyte, protecting the HDGS when it first contacts cementitious media.

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. The sol-gel process used to obtain these coatings allows the variation of the different synthesis parameters to achieve coatings with optimized properties. In this work, hybrid films with different Zr/Si ratios were synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors. Electrochemical Impedance Spectroscopy (EIS) was used to evaluate the corrosion behaviour of coated aluminium specimens in 0.5 M NaCl solution. The morphology and chemical structure of the hybrid coatings prepared were studied by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), Fourier Transformed Infrared Spectroscopy (FTIR) and Thermo Gravimetric Analysis (TGA). It was found that increasing Zr/Si ratio leads to a more cross linked inorganic network, resulting in higher initial coatings resistance, but may turn coatings more hydrophilic, prone to rapid degradation in water, due to a less connected organic network. Consequently, the best anticorrosive performance derives from the balance between the two opposite trends and it was achieved with Zr/Si molar ratio of 0.25.

A incorporação de resíduos industriais em matrizes cimentícias, com o objetivo de inertização, é uma alternativa de reutilização que tem sido bastante estudada nos últimos anos. No presente trabalho, estudou-se a lama vermelha, resíduo sólido gerado no processo de beneficiamento de bauxita e que, devido a seu elevado pH, é considerado “perigoso”. Apesar do uso deste resíduo ter sido reportada em trabalhos anteriores, algumas patologias podem estar associadas à sua utilização, devido à elevada concentração de iões alcalinos (principalmente o sódio), favorecendo as reações álcalis-sílica (RAS) e às dificuldades de moldagem (reologia) devido à elevada finura deste resíduo. Apesar destes prováveis problemas provenientes do uso indiscriminado da lama vermelha como adição às argamassas e betões, ainda são poucas as pesquisas que os contemplam, sendo este o foco do presente trabalho. Foram verificadas as propriedades reológicas das argamassas, utilizando um reómetro e a avaliação da RAS, de acordo com as normas ASTM C 1260-07 e NBR 11582. Os resultados obtidos foram bastante satisfatórios quanto ao comportamento das argamassas frente à RAS, apesar da elevada concentração de álcalis na lama vermelha, com grande influência reológica.

Mortars constituted of lime mixtures with pozzolanic additions have been extensively used in the past for the construction of historic and traditional buildings. This paper presents the results of blended pastes of lime and metakaolin (MK), namely compounds formed and their stability over time. This research is part of an extensive study aiming at the formulation of lime based mortars for restoration purposes. It has been shown for several years that MK has been applied in inorganic binders due to its capacity to react vigorously with calcium hydroxide (CH). In the presence of water originating a series of major hydrated phases, namely tetra calcium aluminate hydrate (C4AH13), calcium silicates hydrates (CSH) and calcium aluminium silicate hydrates (stratlingite – C2ASH8). Several blended pastes of lime and MK, with different substitution rates of lime by MK (wt%) were prepared and cured at a temperature of 20 ?C and relative humidity RH > 95%. The phase composition of the formed hydrated phases was determined by X-ray diffraction (XRD) and simultaneous thermal analysis (TG–DTA). The obtained results showed that lime/MK pastes compositions displayed different reaction kinetics during curing time, being the pozzolanic products content directly proportional to the substitution rate of lime by MK. Also, a relationship between the increase stratlingite content and the MK substitution rate of lime by MK was found.

Metakaolin (MK) is nowadays a well-known pozzolanic material being used in cement-based materials, like mortars and concretes. The reaction of MK with calcium hydroxide yields cementitious products, being calcium silicate hydrate (CSH), stratlingite (C2ASH8) and tetra calcium aluminium hydrate (C4AH13) the main phases formed at ambient temperature. The transformation of stratlingite and C4AH13 into hydrogarnet at long term is an important issue that may result in an increase in the porosity and a loss of compressive strength that can induce a complete material degradation. With the objective of studying the compounds formed in lime/MK pastes and their stability during time, blended pastes were prepared with several substitution rates (in weight) of lime by MK, and maintained at RH>95% and 23 ± 2 ºC. XRD and TGA-DTA were used to follow the kinetics of the lime/MK hydration as well the reaction products. Microscopic tests (SEM-EDS) results are performed and compared with the thermal and mineralogical data. The results obtained show that the quantity of the hydration products formed changes with the lime replacement, being the aluminum and calcium silicates more abundant in the higher MK content pastes, and C4AH13, C4ACH11 and C2ASH8 the major phases formed up to 90 days of curing.

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.

Recommendations on the intervention plans, materials, and techniques for the conservation and restoration of built heritage should be based on sound knowledge of both heritage and its constituent materials conservation condition. Accordingly, data on built heritage and building materials and their history is essential for improvingknowledge on ancient materials and techniques, for materials performance modelling benchmarking and related development, and for further supporting the decision-making process for the conservation/restoration works.Nevertheless, of the latest developments and increased awareness, basic information on physical, chemical, and mechanical characterisation of construction materials is not always accessible or findable. To prevent these shortcomings, DB-HERITAGE system (http://dbheritage.lnec.pt/) provides physical and digital repositories for archiving data on the history, properties and performance of architectural and archeologic heritage and related building materials.This paper displays examples of samples and the related data from historic building materials, including wrought iron, protection coating and mortars, archived at DBHERITAGE, highlighting their scientific, educational, and historical values.

Recommendations on the intervention plans, materials, and techniques for theconservation and restoration of built heritage should be based on sound knowledge ofboth heritage and its constituent materials conservation condition. Accordingly, data onbuilt heritage and building materials and their history is essential for improvingknowledge on ancient materials and techniques, for materials performance modellingbenchmarking and related development, and for further supporting the decision-makingprocess for the conservation/restoration works.Nevertheless, of the latest developments and increased awareness, basic information onphysical, chemical, and mechanical characterisation of construction materials is notalways accessible or findable. To prevent these shortcomings, DB-HERITAGE system(http://dbheritage.lnec.pt/) provides physical and digital repositories for archiving dataon the history, properties and performance of architectural and archeologic heritage andrelated building materials.This paper displays examples of samples and the related data from historic buildingmaterials, including wrought iron, protection coating and mortars, archived at DBHERITAGE,highlighting their scientific, educational, and historical values.

Electrochemistry can provide valuable information on metallic artifacts patinas stability and conservation treatments performance. Therefore, the use of electrochemical techniques in multi-analytical studies on the conservation-restoration of outdoor copper statuary alloys has increased over the last two decades. However, despite some recent developments, for reaching their full potential, especially as regards in situ nondestructive testing there is still subject matter to be explored [1-3].The two case studies included in this communication highlight the usefulness of the non-destructive electrochemical techniques within the framework of conservation studies of copper alloy outdoor monuments.One case study refers to a 220-year-old bronze monument. Within a multi-analytical approach for the conservation state diagnosis [4], in situ measurements of electrochemical potential and resistivity were carried out over representative areas of the surface patinas. The electrochemical test results, in agreement with the other findings, revealed the less protected zones of the statue and contributed to prioritize the required interventions.The other case study aimed the assessment of conservation treatments developed for outdoor bronze monuments [5]. In this study, the electrochemical impedance spectroscopy (EIS) was used to evaluate the efficacy and the durability of innovative treatments comprising eco-friendly products and procedures, such as organo-silanes coatings, limewater and cuprite deposition. These were applied to copper/bronze (85Cu5Sn5Pb5Zn) substrates with natural and artificial patinas representing urban and marine environments. Electrochemical impedance spectroscopy was carried out before and after weathering, according to the patina type, under natural exposure in a marine environment (C5, Cabo Raso test site) and artificial weathering in UV+sulphate salt spray chambers [6]. Untreated and Incralac® (reference) treated specimens were also evaluated for comparison. The EIS testing results showed that some of the new treatments presented better protective properties (higher and more durable corrosion resistance) than the reference treatment, being a viable eco-friendly option for bronze conservation. EIS is an important tool not only for testing and predicting the corrosion protection performance of conservation treatments applied to copper alloys, but also for understanding the processes involved in their degradation.

A conservação e restauro do património arquitetónico construído é uma área de atuação complexa e que, por isso, exige uma grande interdisciplinaridade. Várias intervenções realizadas em Portugal optaram pela remoção dos revestimentos antigos e pela aplicação de novos revestimentos com ligantes mais recentes. Porém, os monumentos onde este tipo de intervenções ocorreu desenvolveram anomalias graves devido à incompatibilidade entre os novos revestimentos e os pré-existentes. Isto torna necessário no futuro a adoção de requisitos que garantam a compatibilidade entre materiais, o que implica um melhor conhecimento das características físicas, mecânicas, químicas e microestruturais dos revestimentos antigos. O estudo de revestimentos antigos permite obter um conhecimento bastante profundo sobre os materiais utilizados, a técnica de aplicação e execução, e complementarmente sobre a história dos próprios monumentos. Neste contexto, o estudo de revestimentos de diferentes períodos e locais diversos, e que tenham também estado sujeitos a diferentes condições de exposição, permite a obtenção de informação valiosa para a conservação de revestimentos antigos, nomeadamente nos casos em que demostraram com o passar dos séculos o seu bom desempenho. Esta informação também permitirá a formulação e aplicação de revestimentos no futuro com maior durabilidade. Nesta comunicação apresentam-se exemplos de estudos em Portugal de caracterização de revestimentos de cal em que se demonstra a necessidade duma abordagem integrada para um melhor conhecimento desses materiais e do seu estado de conservação. É ainda abordada a necessidade do registo e disponibilização dessa informação a todos os intervenientes e ao público em geral, nomeadamente através de repositórios de informação como é exemplo a base de dados de materiais portuguesa de construção com interesse histórico e patrimonial DB-Heritage.

É reconhecido que as intervenções de conservação e restauro em edifícios e monumentos antigos devem respeitar os materiais originais, implicando por isso o conhecimento das características dos materiais, originais e de reparação, bem como os seus desempenhos nas condições de uso. O registo e preservação de informação sobre o desempenho de diferentes tipos de materiais de construção é útil em termos do valor histórico dos materiais, mas também para a inovação e desenvolvimento na área da preservação do património construído. Partindo dum largo arquivo de informação já existente e em constante desenvolvimento, mas disperso por várias entidades, sobre a caracterização física, química e mecânica de materiais, projetou-se o projeto DB-HERITAGE (Base de dados de materiais de construção com interesse histórico e patrimonial) com o objetivo de construír um repositório de materiais históricos. O repositório inclui a compilação física de amostras de referência e uma aplicação para registo sistematizado de dados relativos à história, propriedades e desempenho dos materiais. Pretende-se assim criar uma plataforma de investigação sobre o desempenho passado e futuro de materiais de construção históricos. A cal e as argamassas de cal são um dos materiais históricos incluídos, com grande quantidade de informação já recolhida. Neste artigo apresentam-se alguns dos meios criados pelo projeto DB-HERITAGE ilustrando o seu potencial de partilha e divulgação de informação com alguns exemplos de dados relativos à composição, estado de conservação e desempenho de revestimentos com base em cal em monumentos de interesse histórico e patrimonial.

Conservation and restoration of architectural heritage requires knowledge of the conservation state of its constituent materials in order to provide recommendations concerning the intervention plan, and the materials and the techniques to be used. Information on physical, chemical and mechanical characterization of materials, when available, is usually shared by different actors, but is not normally accessible by the general public. In this context, the DB-HERITAGE project intends to build a reference sample collection or repository for historical materials and an IT-tool to collect the related data on construction materials history, properties, and performance. This database is being developed to categorize materials by type and function, addressing the relevant issues in the historical context of construction materials. An overview of the database tools will be presented in this paper, exemplifying some of its outputs.

Swelling processes due to alkali-silica reactions are a major limitation to durability of concrete dams and hydraulic structures. These reactions occur in high humidity environments between the aggregates and the alkaline cement interstitial fluids, resulting in the formation of expansive alkali-silica gels. The speed, or even the occurrence, of these reactions is quite difficult to predict because it is not related simply to the mineralogical nature of the aggregates. A mineral can even prove to be stable or unstable in different rocks and the relative reactivity of various minerals is also different from aggregate to aggregate. So, there is controversy about which are the factors (chemical composition, structural type, micro-deformation, …) that effectively control the alkali reactivity observed in some aggregates. Besides, there is no consensus about what kind of alkaline minerals are more likely to release alkalis to the interstitial cement solution, and also on the factors that accelerate that solubilisation. This paper aims to contribute to the ongoing discussion of this topic, and so different granitic aggregates, with sound and altered factions, were subjected to alkaline solubility tests in order to measure the alkalis released and to identify the mineral phases that contribute to alkali media raise. The results obtained confirm that granitic aggregates release alkalis in alkaline environment, being this release dependent on the degree of alteration of these aggregates. Natural altered aggregates have less capacity to release alkalis than the non-altered aggregates. In the tested granite samples we observe a higher release of potassium, which is attributed to the higher natural alteration of plagioclase in comparison to K-feldspars.

Awarded for the first time in 1902, the Valmor Prize is one of the most prestigious architecture awards in Portugal. The need to protect the buildings that date back to the beginning of the 20th century, leads to a strategy of intervention carrying out adequate methodologies that must support the selection of repair and substitutive compatible materials. The aim of this study is the knowledge of the building materials employed and their state of conservation, namely the rendering mortars and concrete employed in the buildings awarded. The study of these characteristics will allow the understanding of the evolution of constrained degradation in a given period and constructive context, as well as providing rehabilitation solutions (e.g. compatibility of construction materials, prevention of degradation). In this paper some of these aspects referring to a range of buildings awarded with the Valmor Prize are presented.

O projeto DB-HERITAGE (Database of building materials with historical and heritage interest, PTDC/EPH-PAT/4684/2014, financiado pela Fundação para a Ciência e Tecnologia) tem como principal objetivo a criação de meios para arquivo de materiais de construção históricos que integrem um espaço para repositório de amostras físicas, mas também ferramentas para recolha e divulgação de dados sobre a sua história, propriedades e desempenho. Este desenvolvimento visa a partilha, por diferentes atores e pelo público em geral, de informação relevante sobre os materiais que compõem o património arquitetónico que, por sua vez, sirva de base à elaboração de recomendações para a sua preservação. Em particular, a base de dados em desenvolvimento agrupa os materiais por tipo, função, propriedades, aplicação e cronologia de intervenções, bem como condições de exposição, integrando todos os fatores relevantes para a análise do seu desempenho e do estado de conservação. Neste artigo apresentam-se alguns dos meios criados pelo projeto DB-HERITAGE e, a título ilustrativo, exemplos de dados atualmente disponíveis na base de dados demonstrando o seu potencial na partilha e divulgação de informação relativa a materiais de construção com interesse histórico e patrimonial.

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.

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.