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This paper intends to analyze the microstructure of concrete with recycled aggregates (RA) from construction and demolition waste from various Portuguese recycling plants. To that effect, several scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed. Various concrete mixes were evaluated in order to analyze the influence of the RA’s collection point and consequently of their composition on the mixes’ characteristics. Afterward all the mixes were subjected to the capillary water absorption test in order to quantitatively evaluate their porosity. Results from the SEM/EDS analysis were compared with those from capillary water absorption test. The SEM/EDS analysis showed that the bond capacity of aggregates to the new cement paste is greatly influenced by the RA’s nature. On the other hand, there was an increase in porosity with the incorporation of RA.

In this paper the characterization of a gypsum plaster sample from the end of the 19th century simulating imperial red porphyry using a multi-analytical approach is presented and discussed. The results of X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TGA-DTA), physical and mechanical properties are summarized. In order to have further insight into the microstructure, polarized light microscopy (PLM), scanning electron microscopy coupled with energy dispersive X-ray spectrometer (SEMEDS), and micro Raman spectroscopy analyzes were also made. They helped to clarify the main issues raised by the other complementary analytical techniques and allowed the establishment of interrelations between the different properties, providing important information about the materials, the skills, and the technological development involved in the art of imitating noble stones with gypsum pastes. This study also contributes to our knowledge concerning the preservation of these types of elements that are important in the context of European decorative arts and rarely reported in the literature.

The potentialities of nanomaterials for application in the field of conservation have been widely investigated in the last two decades. Among nanomaterials, nanolimes, i.e., dispersions of lime nanoparticles in alcohols are promising consolidating products for calcareous materials. Nanolimes are effective in recovering the very superficial loss of cohesion of decayed materials, but they do not always provide sufficient mass consolidation. This limitation is mainly related to the deposition of the nanoparticles nearby the surface of the material. Experimental research has been set up with the aim of improving the in-depth deposition of lime nanoparticles. Previous research by the authors has shown that nanolime deposition within a substrate can be controlled by adapting the nanolimes properties (kinetic stability and evaporation rate) to the moisture transport behavior of the substrate. Nanolime properties can be modified by the use of different solvents. In this research, nanolime dispersions have been further optimized for application on Maastricht limestone, a coarse porous limestone. Firstly, nanolimes were synthesized and dispersed in ethanol and/or water, both pure and mixed in different percentages. Subsequently, based on the kinetic stability of the nanolime dispersions, the most promising solvent mixtures were selected and applied on the limestone. The deposition of lime nanoparticles within the limestone was studied by phenolphthalein test, optical microscopy and scanning electron microscopy. The results confirm that nanolime dispersed in a mixture of ethanol (95 %) and water (5 %) can guarantee a better nanoparticles in-depth deposition within coarse porous substrates, when compared to dispersions in pure ethanol.

Several cases of alkali-silica reaction involving granitic aggregates have been diagnosed in damaged concrete structures in Portugal. Nonetheless, this kind of rock is usually regarded as slow/late reactive or even non-reactive to alkalis. Granitic rocks are widely exploited in Northern and Central Portugal, representing almost half of the produced aggregates in this country. Project IMPROVE rose from the need to accurately diagnose the potential reactivity of granites to alkalis. The study involved about forty granites collected from different regions in Portugal, from which the results of eight samples are being presented in this paper. The tests carried out include the petrographic analyses of the aggregates and mortar and concrete expansion tests. It was concluded that the content of microcrystalline quartz correlates better with the results of AAR-4.1 than with the other expansion tests.

Several cases of alkali-silica reaction involving granitic aggregates have been diagnosed in damaged concrete structures in Portugal. Nonetheless, this kind of rock is usually regarded as slow/late reactive or even non-reactive to alkalis. Granitic rocks are widely exploited in Northern and Central Portugal, representing almost half of the produced aggregates in this country. Project IMPROVE rose from the need to accurately diagnose the potential reactivity of granites to alkalis. The study involved about forty granites collected from different regions in Portugal, from which the results of eight samples are being presented in this paper. The tests carried out include the petrographic analyses of the aggregates and mortar and concrete expansion tests. It was concluded that the content of microcrystalline quartz correlates better with the results of AAR-4.1 than with the other expansion tests.

Novel nanomaterials, such as nanosilica or nano-titanium oxide, have been developed in the last decade for the conservation of the built heritage. Among nanomaterials, nanolimes have acquired a considerable relevance due to their potentialities as consolidant product. The so-called nanolimes, colloidal dispersions of calcium hydroxide nanoparticles in alcohols, have been successfully applied as pre-consolidants on frescos and paper, and their use has later been extended to plasters, renders and stone. Nanolimes have better potentialities compared to conventional inorganic consolidants based on limewater (e.g. faster carbonation rate and higher calcium hydroxide concentration). Moreover, nanolimes are considered more compatible with CaCO3-based substrates than alkoxysilanes (e.g. TEOS), the most widely used consolidant products. Nanolimes can guarantee the recovery of the superficial cohesion of degraded materials. However, when a mass consolidation is required, like in the case of decayed stone, nanolimes show some limitations. One of the problems is caused by nanolime accumulation at or just beneath the surface of the treated material. In order to solve this problem, the transport mechanism of nanolime within porous materials, as stone or renders, should first be better understood. Commercial nanolimes were applied on Maastricht limestone, a high-porosity yellowish limestone, used in the Netherlands and Belgium as traditional building material. The absorption and drying behaviour of nanolime in this limestone was measured and nanolime deposition in the stone was studied by optical and scanning electron microscopy. The results show that nanolime transport is strictly related to the properties of the solvent. The alcoholic solvent guarantees a stable dispersion that penetrates in depth in the material, but is partially back-transported to surface. The high volatility of the solvent and the high stability of the dispersion favour the partial back-migration of lime nanoparticles to the surface during drying.

O desenvolvimento do Homem e, em geral, da Sociedade tem estado intimamente associado ao uso que tem sabido fazer dos recursos minerais disponíveis. Parte desse desenvolvimento consubstanciou-se na utilização de materiais, naturais ou processados, nomeadamente na construção de grandes estruturas, algumas consideradas marcos duma determinada época ou civilização. Muitas dessas estruturas têm resistido ao passar dos anos e são, em termos da sua longevidade e durabilidade, um desafio para as construções atuais. É neste contexto que os estudos composicionais dos materiais de construção antigos têm ganho um reconhecimento crescente, pois por um lado possibilitam obter informação que permita de uma forma adequada a sua conservação e restauro, mas também potenciar a melhoria do desempenho de novos materiais. Estes dois objetivos, diferentes mas que se interligam, necessitam de conhecimentos de química e o recurso a métodos de análise físico-químicos de caraterização de materiais. Neste artigo descrevem-se dois exemplos de casos de estudo de caraterização de argamassas de monumentos antigos em Portugal, que evidenciam a importância da química quer no estudo de materiais, como para a história desses monumentos e do património histórico e arquitetónico em geral.

Historical renders are exposed to several degradation processes that can lead to a wide range of anomalies, such as scaling, detachments, and pulverization. Among the common anomalies, the loss of cohesion and of adhesion are usually identified as the most difficult to repair; these anomalies still need to be deeply studied to design compatible, durable, and sustainable conservation treatments. The restitution of render cohesion can be achieved using consolidating products. Nevertheless, repair treatments could induce aesthetic alterations, and, therefore, are usually followed by chromatic reintegration. This work aims to study the effectiveness of mineral products as consolidants for lime-based mortars and simultaneously as chromatic treatments for pigmented renders. The studied consolidating products are prepared by mixing air lime, metakaolin, water, and mineral pigments. The idea of these consolidating and coloring products rises from a traditional lime-based technique, the limewash, widely diffused in southern Europe and in the Mediterranean area. Consolidating products were applied and tested on lime-based mortar specimens with a low binder–aggregate ratio and therefore with reduced cohesion. A physico-mechanical, microstructural, and mineralogical characterization was performed on untreated and treated specimens, in order to evaluate the efficacy and durability of the treatments. Accelerated aging tests were also performed to assess consolidant durability, when subjected to aggressive conditions. Results showed that the consolidants tested are compatible, effective, and possess good durability.

O Forte de Nossa Senhora da Graça localiza-se no Monte de Nossa Senhora da Graça, a norte da cidade de Elvas. É construído no final do século XVIII a mando de D. José I, classificado como Património Nacional em 1910 e como Património Mundial, pela UNESCO, em 2012. Na construção do forte utilizaram-se pedras e terras sobrantes das minas abertas no maciço rochoso do monte, assim como outros materiais existentes nas proximidades do local da construção, tal como areia e material cerâmico. No âmbito da sua nomeação pela UNESCO, em 2012, em conjunto com as restantes fortificações de Elvas, como Património Mundial, foi implementado um plano de conservação e restauro do Forte que envolve, entre outras atividades, uma caracterização detalhada dos materiais empregues na sua construção.

This research was focused on the use of the modified Chapelle test as a direct laboratory methodology to access the pozzolanic activity of both experimental and commercial metakaolins. At the same time, this test was used in the evaluation of experimental metakaolins. This chemical test, performed during 16 hours at 90 °C, allows the quantification of portlandite fixed by the metakaolin sample. The calcium hydroxide that was not consumed is quantified by acid titration (HCl), and the test result is expressed in mg of fixed calcium hydroxide by g of metakaolin. According to this test, the pozzolanic activity of a metakaolin should not be less than 700 mg Ca(OH)2 / g metakaolin. The modified Chapelle pozzolanic activity of six commercial metakaolins was evaluated between 920 and 1560 mg Ca(OH)2 / g metakaolin. From the seven experimental metakaolins produced between 750 ºC and 940 ºC, a material with modified Chapelle pozzolanic activity value of 1240 mg Ca(OH)2 / g metakaolin was obtained, which is similar to some tested commercial metakaolins produced at industrial scale. The metakaolin produced at 800 ºC was ground, resulting in a particle size reduction of ? 4x less and a consequent increase of 21 % in the pozzolanic activity.

The consolidation process of old renders with loss of cohesion is nowadays performed usually with inorganic compatible products, such as calcium or barium hydroxide or ethyl silicate. The use of organic consolidants as acrylic or vinilic resins is discouraged due to its physico-chemical incompatibility with the original lime-based renders; these organic products work as adhesive in the original substrate, while inorganic consolidants contribute to recover the cohesion loss improving the binder amount and guarantying better durability and full compatibility. The restoration intervention on historic mortars, including consolidation, often causes aesthetic heterogeneity and prejudices, sometimes dramatically, the global legibility of the architectonic surface. The aesthetic function can be restored by chromatic reintegration, through several techniques, with resource to overpaints, for instance based on calcium hydroxide, pigments and silicates. In this study several consolidant lime-based products were produced and characterized. Pigments were added to the products, in order to achieve chromatic reintegration properties as well as consolidation. The consolidant products consist in aqueous dispersion of calcium hydroxide, a pozzolanic additive (metakaolin or diatomite) and mineral pigments, namely a yellow earth pigment and a synthetic red pigment. The incorporation of a pozzolanic material was made to improve the mechanical strength and durability of the binder. The consolidant products were applied on mortar specimen with a simulated cohesion loss, through a reduced binder quantity and an optimization of the aggregate grain size. Specimens were subjected to both wet and dry cure, to verify the influence of storage and curing conditions. Physico-mechanical and microstructural characterization was performed on the treated mortar specimens to verify the consolidant treatment efficacy. Consolidant treatments show intesting results, and their efficacy vary depending on the pozolanic addition; pigments do not influence that much the consolidation efficiency.

A functionalized siloxane and five amino terminated oligopolymers were used to produce, by sol-gel method and using a dip-coating process, OIH coating films as an alternative pre-treatment to prevent the corrosion of galvanized steel in concrete. The influence of residence time (RT), cure and number of dip steps on the coverage and uniformity of the obtained coatings dipped at a withdrawal speed of 10 mm min-1 for each oligopolymer were studied. The surface morphology and the depth chemical composition of the obtained coatings were analysed by SEM/EDS and GD-OES techniques. The results showed that the coverage and uniformity of the hybrid coating deposited on the HDGS surface improves with the increase on RT and number of dip steps. Nevertheless, full coverage is seldom achieved and the final OIH coatings thickness is very irregular.

O projeto DURATINET tem como objetivo fundamental a criação de uma rede transnacional no Espaço Atlântico que facilite a transferência de conhecimentos entre os centros de investigação e os utilizadores finais destes conhecimentos, nomeadamente, os donos de obra e gestores das infraestruturas, empresas de construção e engenheiros de projeto e de fiscalização, de forma a contribuir para a promoção da durabilidade e da segurança das infraestruturas de transporte. Foram igualmente visados diferentes aspetos associados a uma construção mais sustentável. Os principais resultados deste projeto foram: publicação de um guia técnico de recomendações para a conservação e reparação de infraestruturas de transporte; criação de uma ferramenta na internet com uma versão interativa do guia técnico; e criação de uma base de dados (DB-DURATI) sobre desempenho de materiais.

An important operation for the conservation of historical renders is the cohesion restitution of the binder-aggregate system, based on the use of materials with consolidating properties. Inorganic consolidants are usually preferred to organic ones due to better compatibility and durability. The aim of this work is the experimental characterization of two nanostructured consolidant products; a commercial nanolime, optimized with the addition of a reduced concentration of ethyl silicate, and a commercial nanosilica product underwent experiments to verify their consolidation efficiency. Nanostructured lime-based and silica-based products present interesting properties such as homogeneous distribution and high stability. Nanolimes were applied in combined applications with ethyl silicate, a well-known compatible product for consolidation intervention. The combined application guarantees some benefits and improves the mechanical and microstructural performance of these products. A nanosilica product was tested to better understand some known disadvantages (e.g. reduced penetration depth) and so its performances. Consolidant products were applied on weak lime mortar samples (prismatic samples and single mortar layer applied on bricks); these mortars were optimized by studying different binder-aggregate ratios, to simulate old lime mortar with cohesion loss. Consolidation effects were periodically evaluated to understand the treatments efficacy. Physical-mechanical characterization was performed on treated mortar samples, analysing superficial hardness and compressive and flexural strength. Microstructural observations and X-ray microanalyses of the consolidation products and of the consolidated mortar samples are also reported

In this work, the effect of alloy surface pre-treatments on the corrosion behaviour of sol–gel hybrid coated EN AW 6063 alloy was studied. Four pre-treatments were used: solvent degreasing; alkaline degreasing followed by acid etching; alkaline degreasing followed by alkaline plus acid etching and alkaline degreasing followed by acid etching and oxide growth in boiling water. SEM/EDS revealed that the alloy surface depends on the pre-treatment. The alkaline plus acid cleaned samples exhibited a very smooth deoxidized surface. All the others showed a rougher surface with an oxide layer which is more homogenous and denser in the samples subjected to the oxide growth step. The sol-gel hybrid coating was synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors and applied to metallic substrate by dip-coating. The corrosion behaviour of the hybrid coated samples was evaluated by Electrochemical Impedance Spectroscopy (EIS) and by an accelerated corrosion test. Complimentary to the corrosion study, the adhesion of the hybrid sol-gel coating was evaluated by crosscut and bend tests. The corrosion tests revealed that the pre-treatment that includes the oxide growth step leads to the best protection performance, followed by the alkaline degreasing and alkaline plus acid etching one. However, the latter exhibits the worst adhesive behaviour, attributed to the smoother, deoxidized surface of the substrate.

The organic-inorganic hybrid sol-gel films have been reported as an environmentally friendly anti-corrosion pre-treatment for several metals. These types of coatings present combined mechanical and chemical properties typical of inorganic ceramics and of organic polymers [1]. Among these, the epoxy-silane based hybrid sol-gel coatings are of particular interest due to the increased properties of flexibility, density and functional compatibility with organic coatings achieved as a result of the epoxide organic group present [1-3]. During the synthesis of these coatings occurs the simultaneous formation of an organic network through epoxide rings opening and polymerization, and of an inorganic siloxane network through the hydrolysis and subsequent condensation of the silicon alkoxide groups. Uncatalysed organic polymerization usually requires elevated temperature. However, by the addition of amine curing agents it is possible to promote the organic network formation at low temperature [4], with inherent energy savings. In this paper, epoxy-silica-zirconia hybrid sol-gel coatings were synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors, applied to EN AW-6060 alloy by dip-coating and cured at room temperature using the amine crosslinker diethylenetriamine (DETA), in different concentrations (GPTMS/amine- Hreactive molar ratios: 1.5 and 1), and a tri-functional amino-silane in that molar ratio of 1. The evolution of the curing process and the corrosion behaviour of the coated aluminium alloy specimens were evaluated by Electrochemical Impedance Spectroscopy (EIS) in 0.5 M NaCl. The morphology and surface chemistry of the hybrid coatings were also characterized by Energy Dispersive Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM) and by Fourier Transform Infrared Spectroscopy (FTIR). The results obtained revealed that the sol-gel coatings with less amine require longer times to finish cure. Once cured, these coatings have shown the best anticorrosive performance with time. It was found that increasing amine concentration led to a more cross linked organic network, resulting in higher initial coatings resistance, however it has turned coatings more hydrophilic, prone to rapid degradation in water.

Corrosion of steel in concrete in one of the major causes of structures degradation, requiring expensive rehabilitation works. The using of hot dip galvanized steel (HDGS) has been recognized as one effective measure to increase the service life of reinforced concrete structures in marine environmental. However, the HDGS corrodes in contact with the high alkaline environment of fresh concrete. Although this initial process allows the formation of a protecting layer barrier, the corrosion that occurs immediately after concreting is harmful and chromate conversion layers are usually used to prevent it. Environmental and human health concerns have restrained the use of Cr(VI) and some hybrid coatings have been proposed as alternatives. To evaluate the performance of these coatings, beyond the laboratory film characterization, in situ tests in real conditions should be performed. This paper describes an electrochemical system designed to evaluate the in situ degradation of HDGS coated with different hybrid films embedded in concrete. A two parallel electrodes system was selected, using a stainless steel plate as counter electrode (CE) and a HDGS plate coated with hybrid material as working electrode (WE). The WE to CE ratio of the areas is about 1:1, with a spacing between them of 1 cm. The cells were embedded in a mortar using water/cement = 0.5 and sand/cement = 3. The electrochemical measurements of two produced coatings with different thicknesses was performed during 70 days after concreting through reading the potential difference to the terminals of a resistor of 100 ?, using an automatic data acquisition system (Datataker DT505). During the first 7 days, the corrosion rates were expected to be higher so was selected a data acquisition period of 1 min and then changed to 5 min. The results of analysis of the WE of the disassembled cells by optical and scanning electronic microscopy (SEM/EDS) shows to be consistent with data obtained by electrochemical tecnhiques. The system revealed to be highly sensitive to the coatings degradation, allowing distinguishing different hybrid coatings with different thicknesses.

Corrosion of reinforcement is one of the prevailing causes of premature deterioration of reinforced concrete. Among the possible anti-corrosion measures, hot-dip galvanized steel extends protection increasing the service life of the rebars in aggressive environments. The zinc layer acts, as a physical barrier that hinders the contact of the aggressive agents with the steel substrate and zinc becomes a sacrificial anode protecting the steel against corrosion even when damage occurs in the concrete. Once the galvanized rebars are placed in contact with fresh concrete (alkaline environment) zinc is attacked by the calcium hydroxide, leading to the formation of calcium hydroxizincate and hydrogen. To reduce the formation of excessive amounts of zinc oxides as well H2 evolution, chromium compounds are usually used in the final concrete mix (?100 ppm of Cr) or the rebars must be previously passivated with a chromate conversion layer. The high corrosion resistance offered by the use of chromate films is endorsed to the presence of Cr6+, however have been reported to be toxic and carcinogenic, so their application is heavily regulated by environmental legislation and an intense research is being undertaken to replace chromates by eco-friendly compounds. Sol-gel technology revealed to be a successful method in coatings technology and in fabrication of organic-inorganic hybrid (OIH) materials. In this work, four OIH sol-gel matrixes based on functionalized metal alkoxide and oligopolymers, identified as having potential to be an alternative to prevent the corrosion of galvanized steel in concrete were deposited by dip coating method. Surface analysis of coated and uncoated substrate was performed by stereoscopy and SEM/EDS before and after being in contact with cementious media (cement paste and mortar). Monitorization of the galvanic current (jgal) of the coated and uncoated substrates were performed during 74 days only in contact with a mortar.

The need to formulate mortar compositions with adequate durability and compatibility is nowadays one of the major challenges in historical buildings repair. The incorporation of pozzolanic materials as addition or replacement of lime is viewed as a solution to these challenges regarding the increase in hardening time, mechanical strength, water resistance and durability. This paper includes part of an extensive work being developed in Portugal, which has the objective of developing and characterizing lime-metakaolin mortars for conservation purposes. This paper evaluates the influence of the curing conditions, namely medium and high relative humidity (HR), lab and outdoor exposition, and direct daily contact with potable or sea water. Two air lime mortars with volumetric proportion 1:3 of binder and aggregate, with 0 and 9% Mk (mass % replacement of air lime) were characterized up to one year of age. The mortars evolution with curing was followed by XRD, TG-DTA, tensile and compressive strength tests. The humid and urban curing revealed the best results in terms of the pozzolanic reaction, occurring mostly at lower curing times (28 days), although carbonation reaction is dominant throughout all ages up to 1 year.

Aluminium alloys of 6000 series are particularly suited for the building industry due to their good corrosion resistance. However, they can suffer severe corrosion in acidic (polluted) and/or marine environments [1] and in contact with alkaline media like fresh cementitious materials. Therefore, architectural aluminium components are often coated to increase durability and aesthetical appearance, what requires its surface pre-treatment, traditionally Cr(VI) based, now facing severe restrictions. Within building industry, several “green” alternative treatments are already being applied, but they lack the anticorrosive action of the Cr(VI) compounds [2]. Another alternative under development, includes sol-gel silane based coatings, in particular, the organic-inorganic hybrid (OIH) ones, since they not only promote adherence, but also provide corrosion protection by barrier effect and in addition can incorporate corrosion inhibitors in their structure [3]. In this work, sol-gel coatings with in situ produced zirconia nanoparticles were synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors by the sol-gel process and applied on EN AW-6063 alloy. Cerium nitrate was added to TPOZ sol during synthesis to be incorporated in the nanoparticles and act as corrosion inhibitor. Then cerium doped and undoped OIH coated aluminium alloy specimens were exposed to neutral, acidic (pH~3) and alkaline (pH~10) chloride solutions to assess coating chemical stability and anticorrosive properties in those media, since aluminium architectural coatings are usually required to be resistant both to acids and alkalis. The corrosion behaviour was evaluated by EIS (electrochemical impedance spectroscopy) and surface was characterized by SEM/EDS analyses.

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.