Papers
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20th Century Mortars: Physical and Mechanical Properties from Awarded Buildings in Lisbon (Portugal)
This paper addresses the study of renders and plasters
Year: 2023
Number Pages:
26p..
Author(s): Mirão, J.; Veiga, M. R.; Santos Silva, A.; Almeida, L.
: Buildings
Editor: MDPI
Volume:
13.
Keywords: Compatibility; 20th century; Portland cement; Lime
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Characterization and assessment of performance of innovative lime mortars for conservation of building heritage: Paimogo
Along the Portuguese coastline, several military fortifications were built with the intention to protect the territory from the constant military threat from the sea. These constructions have been subjected, during centuries, to a very aggressive environment; the renders, whose main function is the protection of walls, are particularly exposed to such actions. Nossa Senhora dos Anjos de Paimogo
Year: 2023
Number Pages:
24p..
Author(s): Santos Silva, A.; Veiga, M. R.; Lopes dos Santos, A. R.
: Applied Sciences
Editor: MDPI
Volume:
13 (8).
Keywords: Performance; Mortar; Lime; Innovative; Durability; Conservation
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Characterization of mortar from Casa Barbot (Portugal), a case study from the beginning of the 20th century
The popularity of natural cement (Roman cement) in buildings from the late 19th and thebeginning of the 20th century and the high diversity of characteristics of natural cement demandresearch of mortar and binders used in the buildings of this period in Portugal. Understandingthe type of binder used in the historic buildings will help the project/intervention team to makethe best decisions in terms of the development of compatible mortars for historical conservationpurposes. Casa Barbot is one of the Art Nouveau examples of the beginning of the 20th century inPortugal. The garden of this building is characterized by peculiar elements in terms of materials andarchitecture. Full characterization of the mortars employed in the construction of this building as wellas identification of the used binder is the main objective of this study. The study comprises a widerange of laboratory characterization techniques such as X-ray fluorescence (XRF), X-ray diffraction(XRD), petrography, open porosity, density, water absorption by capillarity, and compressive strength.The results show the diversity of compositional characteristics in the mortars used in the decorativeelements in the period garden of Casa Barbot. All mortars are composed of Portland cement with amix of additives such as blast furnace slag, limestone filler, air lime, and the occasional presence ofcharcoal. The results raise doubt about the use of natural cement as stated in the historical documents.This study will broaden the scientific knowledge of the materials of that period in Portugal to providea comprehensive plan for the preservation of historical buildings.
Year: 2023
Number Pages:
18p..
Author(s): Maljaee, H.; Velosa, A.; Santos Silva, A.
: Buildings
Editor: MDPI
Volume:
13.
Keywords: Conservation; Art Nouveau; Portland cement; Mortar; 20th century
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Composition of renders and plasters of award-winning buildings in Lisbon (Portugal): A contribution to the knowledge of binders used in the 20th Century
This paper reports on the study of renders and plasters from 20th-century award-winning buildings in Lisbon (Portugal) with the Valmor Prize for Architecture. The mortars have been investigated through XRD, optical and electronic microscopy (SEM-EDS), thermal analysis (TGA/DTA), wet chemical analyses and AAS. The results reveal that the use of air lime lasted until the 1940s. It also highlights the beginning of using of Portland cement in mortars in the 1930s, mixed with airlime, and the abandonment of mortar formulations solely based on air lime. This study highlights the use of finishing lime-gypsum-based mortars until the 1940s and different types of Portland cement from the 1940s onwards. Portland cement was the main binder for the analysed stoneimitating mortars from 1940s to 1970s. Finally, salt contamination was occasionally found in mortars, which generally reveal a good state of conservation
Year: 2023
Number Pages:
31p..
Author(s): Mirão, J.; Veiga, M. R.; Santos Silva, A.; Almeida, L.
: International Journal of Architectural Heritage
Editor: Taylor & Francis
Keywords: Pasters; Renders; Mineralogy; Microscopy; Hydraulic mortars; Characterisation; Aerial mortars; 20th century
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DB-HERITAGE Building Materials Data Aggregation in ARIADNE - challenges and opportunities
DB-HERITAGE provides open and free sharing of wide-ranging technical data on hundreds of samples of building materials from diverse periods, extracted from Portuguese built heritage all over the world. It has been developed to improve know-how for historic building materials and as a basis for developing best practices for built heritage conservation. It incorporates both physical and digital repositories for building material samples and related data, providing tools for the systematic recording of data concerning the history, properties, and performance of materials used in Portuguese built heritage.DB-HERITAGE targets different communities, researchers, and stakeholders involved in the preservation of archaeological and architectural heritage. It provides a systematisation of building assets, within their related environmental, social, and cultural contexts, as well as displaying technical and scientific information on structural elements, built components and their constituent materials. Although the rationale of the wide context sustaining the DB-HERITAGE concept is clear, coordinating communities and reduced time-to-value represent extra requirements for data quality, improved tools, and an efficient management plan.The participation in ARIADNEplus challenged DB-HERITAGE to get the most out of standardised procedures and the FAIR principles, strengthening its data management plan and practices. Data processing has been improved by deploying a common ontology and further developing standards, shared semantics, and identifiers. Updated protocols for data sharing and detailed information on provenance have also been developed to enhance data reuse.This article presents an overview of the aggregation process of DB-HERITAGE data into ARIADNEplus. It includes a summary of DB-HERITAGE's strengths and of the challenges faced within the scope of the aggregation process, with examples of some of DB-HERITAGE's major outputs. Additionally, it considers the benefits and opportunities provided by participation in ARIADNEplus.
Year: 2023
Author(s): Santos Silva, A.; Correia, M. J.
: Internet Archaeology
Editor: UY
Volume:
64.
Keywords: FAIR data; building materials; heritage assets conservation; heritage safeguard
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Fernandina wall of Lisbon: mineralogical and chemical characterization of rammed earth and masonry mortars
This paper aims to provide information on rammed earth and masonry mortars of the Fernandina defensive Wall of Lisbon, Portugal, which was built in the second half of the 14th century. No previous information exists concerning the materials and construction techniques used in this defensive structure, which is essential to increase knowledge and to define requirements for a reliable conservation. An experimental campaign was carried out on samples extracted in nine different sections of this structure, which were analyzed by X-ray diffraction, thermogravimetry and wet chemical analysis. Calcitic lime was employed as a binder in the stone masonry bedding mortars and was also identified in the rammed earth samples. The results obtained allowed us to verify the use of different binders and aggregates, with heterogeneous binder/aggregate ratios, in different sections of the Wall. To reduce time for lime preparation and to achieve a durable lime matrix, most probably quicklime was used and hydrated together with the moistened earth to produce rammed earth and masonry bedding mortars.
Year: 2022
Author(s): Faria, P.; Gomes, L.; Santos Silva, A.; Infante Gomes, R.
: Minerals
Editor: MDPI
Volume:
12.
DOI:
10.3390/min12020241
Keywords: Architectural heritage; Air lime; Rammed earth; Stone masonry bedding mortar; Defensive structure
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Influence of Exposure Conditions and Particulate Deposition on Anodized Aluminum Corrosion
Anodizing is commonly used for corrosion protection of aluminum and its alloys in the construction industry. The anodic aluminum oxide (AAO) coating has a high ability to prevent the development of extensive pitting corrosion in aluminum substrates, particularly in marine sites, as was observed during a 10-year atmospheric corrosion study carried out in several marine and industrial sites. However, this study also evidenced that this coating can be highly affected by the deposition of particulate material in industrial polluted environments, sometimes in unexpected ways. This study presents information on the atmospheric corrosion of anodized aluminum exposed at two different chemical industrial complexes: a fertilizer production plant and a pulp and paper mill. Visual assessment of surface changes, pitting depth and mass variation with exposure were determined to quantify the degradation suffered. Additionally, SEM/EDS analyses were carried out on the exposed surfaces. Based on the results obtained, the role played by the deposition of airborne particles present in the two environments with respect to the type and level of damage observed is discussed. Deposits of roasted pyrite ash and phosphates or of wood chips and lime particles enhanced pitting corrosion or caused dissolution of the AAO coating.
Year: 2022
Number Pages:
770-786pp..
Author(s): Pereira, E. V.; Fontinha, I. R.
: Corros. Mater. Degrad.
Editor: MDPI
Volume:
2022 3(4).
Keywords: anodized aluminum; atmospheric corrosion tests
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Metais modernos em património edificado: desempenho em ambiente exterior.
Os materiais metálicos do século XX apresentam propriedades físicas e de resistência à corrosão com interesse para a arquitetura, tendo neste âmbito uma ampla gama de aplicações. Contudo, estão sujeitos a degradação, frequentemente associada às condições de utilização e ambiente de exposição, cujas consequências vão desde alterações estéticas à perda de funcionalidade dos componentes e estruturas em que se encontram aplicados. Neste artigo, descreve-se o comportamento típico de vários materiais metálicos correntemente usados nas edificações, quando usados em componentes de arquitetura exterior, correlacionando-o com a corrosividade ambiental e modos de utilização. O conjunto de informação reunida teve como objetivo contribuir para uma seleção adequada dos metais a aplicar numa determinada obra.
Year: 2021
Number Pages:
181-204.
Author(s): Fontinha, I. R.
: Cadernos do Arquivo Municipal
Editor: Arquivo Municipal de Lisboa, Câmara Municipal de Lisboa
Volume:
Nº16 (julho-dezembro 2021),.
Keywords: Pátinas; Atmosfera; Corrosão; Metais
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Electrodialytic removal of tungsten and arsenic from secondary mine resources Deep eutectic solvents enhancement
Tungsten is a critical raw material for European and U.S. economies. Tungsten mine residues, usually considered an environmental burden due to e.g. arsenic content, are also secondary tungsten resources. The electrodialytic (ED) process and deep eutectic solvents (DES) have been successfully and independently applied for the extraction of metals from different complex environmental matrices. In this study a proof of concept demonstrates that coupling DES in a two-compartment ED set-up enhances the removal and separation of arsenic and tungsten from Panasqueira mine secondary resources. Choline chloride with malonic acid (1:2), and choline chloride with oxalic acid (1:1) were the DES that in batch extracted the average maximum contents of arsenic (16%) and tungsten (9%) from the residues. However, when ED was operated at a current intensity of 100 mA for 4 days, the extraction yields increased 22% for arsenic and 11% for tungsten, comparing to the tests with no current. From the total arsenic and tungsten extracted, 82% and 77% respectively were successfully removed from the matrix compartment, as they electromigrated to the anolyte compartment, from where these elements can be further separated. This achievement potentiates circular economy, as the final treated residue could be incorporated in construction materials production, mitigating current environmental problems in both mining and construction sectors.
Year: 2020
Author(s): Almeida, J.; Craveiro, R.; Faria, P.; Santos Silva, A.; Mateus, E.; Barreiros, S.; Paiva, A.; Ribeiro, A.
: Science of The Total Environment
Editor: Elsevier
Volume:
Volume 710.
Keywords: Choline chloride/oxalic acid; Choline chloride/malonic acid; Electro-based technology; Secondary resource; Harmful compound; Critical raw material
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Tensile bond strength of lime-based mortars: The role of the microstructure on their performance assessed by a new non-standard test method
In recent years the study of renderings within conservation practice has acquired major technical and methodological advances. Due to the need of compatibility, usually repair mortars must be based on lime, and standardized tests are sometimes ineffective for these compatible substitution materials, which are often low strength mortars. The influence of the aggregates' characteristics on several factors that affect the adhesive strength of lime-based mortars is assessed and a new non-standard test method to determine the tensile bond strength of low strength mortars to porous substrates is presented and validated. The outcome shows that the new methodology offers the advantages of precision of the test device, ease of application and mostly consistency of the results. Furthermore, the main data show close relationship between the tensile bond strength and the pore size distribution of the mortars, which is very sensitive to the aggregates characteristics: In general, increasing the mortars pore volume of coarse pores (above the critical pore diameter of the substrate) strengthens the effective bond between these elements. Moreover, the compositional similarity between the aggregates and the substrate could also favour the bond between these elements.
Year: 2020
Author(s): Lopes dos Santos, A. R.; Veiga, M. R.; Santos Silva, A.; Brito, J.
: Journal of Building Engineering
Editor: Elsevier
Volume:
Volume 29.
Keywords: Rehabilitation; New tensile bond strength test; Microstructure; Lime-based mortar; Aggregate
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Comunicação
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Inhibition of ASR and DEF: evaluation of the microstructure of concrete mixes with pozzolanic additions
The use of pozzolanic mineral additions is a known method to inhibit the expansive chemical reactions in concrete, like the alkali-silica reaction (ASR) or the delayed ettringite formation (DEF). The ASR is a chemical reaction that occurs between certain types of minerals present in aggregates and alkali and hydroxyl ions present in the interstitial solution of cement paste in concrete. This reaction involve the dissolution of amorphous or poorly crystallized forms of silica, in alkaline medium, with the formation of an alkaline hygroscopic gel that absorbs water and expands, creating internal stresses in the concrete with cracking. The DEF is a pathology related with the formation of expansive ettringite due to an excessive heating of the concrete during the cure that induces swelling, cracking and decrease of the mechanical properties of the hardened concrete. This paper presents the results of SEM/EDS analysis of concrete mixes with different pozzolanic materials, like metakaolin, biomass fly ash, natural pozzolan and mine sludge from a tungsten mine. The microstructural evaluation is discussed and correlated with the expansion data of each concrete mix.
Year: 2011
Number Pages:
15p.
Author(s): Santos Silva, A.; Soares, D.; Matos, L.; Divet, L.; Salta, M. M.
Editor: ZAG, Slovenian National Building and Civil Engineering Institute
Keywords: Pozzolanic additions; Microstructure; Scanning electron microscopy; Def; Asr
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Investigation of Alkali-Silica Reaction in Concretes with Biomass Fly Ash
The alkalisilica reaction (ASR) in concrete occurs by reaction of certain silica phases in the aggregates with alkalis and hydroxide ions in the pore solution of the hydrating cement to produce a hydrous alkali-silicate gel. This gel can swell by incorporating large amounts of water, causing severe and irreversible expansion and cracking of the concrete. The level of expansion and disruption in concrete containing reactive aggregate depends on the alkali content of the concrete and the reactivity of the aggregate. The levels of alkali that trigger the expansion depend, however, on the reactivity of the aggregates. Alkalis from Portland cement (OPC) are one of the major sources of these ions in concrete. The use of industrial by-products such as fly ash and slag has been found to be an effective preventive measure against ASR in concrete. This article presents the performance of biomass fly ash - an industrial by-product - in the mitigation/inhibition of ASR in concrete. Laboratory expansion tests were conducted to evaluate the performance of biomass fly ash, in replacement of OPC by 20% and 30% (w/w) in the experiments (ASTM C1260/ASTM C1567). The results revealed that biomass fly ash has a good potential in the expansion inhibition due to ASR.
Year: 2011
Number Pages:
7p.
Author(s): Rejini, R.; Soares, A. C.; Esteves, T.; Santos Silva, A.; Labrincha, J. A.; Ferreira, V.
Editor: Instituto de Ciencias de la Construcción Eduardo Torroja
Keywords: Industrial by-products.; Biomass fly ash; Alkali-silica reaction; Concrete
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Laboratory and microstructural tests on the detection and prediction of AAR
LNEC has been involved in research dealing with alkali-aggregate reactions for the past 20 years. In recent years, the research has been directed at identifying the magnitude of the problem in Portugal, identifying rock types which may be potentially reactive, determining the influence of supplementary cementing materials to counteract the expansion associated to AAR and the continuous improvement of the methodologies to prevent this deleterious reaction in new concrete constructions. International and national workshops and seminars on concrete durability, and particularly related to the concrete degradation by alkali-aggregate reactions, have been held to disseminate the information. One integral part of this research work has been the transfer of technology to the universities and concrete industry in the subjected area. This presentation is a perfect example of the cooperation between LNEC and the Portuguese Universities in this specific topic related with the laboratory and microstructural tests on the detection and prediction of AAR.
Year: 2011
Author(s): Santos Silva, A.; Fernandes, I.
Editor: LNEC
Keywords: Prognosis; Diagnosis; Microscopy; Tests; Alkali-silica reaction; Aar
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Metakaolin-lime hydration products and phase stability:
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 the main phases formed at ambient temperature the calcium silicate hydrate (CSH), stratlingite (C2ASH8) and tetra calcium aluminium hydrate (C4AH13). Several discrepancies are presented in literature regarding these phases stability, namely the transformation of stratlingite and C4AH13 into hydrogarnet at long term. The consequences of that instability are 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 50%, 33%, 25%, 17%, 9%, 5% and 0% (wt.%) of MK. These lime/MK pastes were stored at 95% RH and 23 ± 2 ºC. After each predetermined curing time the hydration reaction was stopped subjecting the samples to acetone. TGA-DTA and XRD were used to follow the kinetics of the MK-lime reaction as well the reaction products formed. In this paper the results obtained by the application of microscopic methods, namely by SEM-EDS, are presented and compared with the thermal and mineralogical data.
Year: 2011
Number Pages:
10p.
Author(s): Gameiro, A.; Santos Silva, A.; Veiga, M. R.; Velosa, A.
Editor: ZAG, Slovenian National Building and Civil Engineering Institute
Keywords: Metakaolin; Lime; Tga-dta; Xrd; Microscopy
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Mineral Additions for the Inhibition of Delayed Ettringite Formation in Concrete: The Role of Limestone Filler
One of the most popular preventive measures to minimize the occurrence of chemical expansive reactions, namely the internal sulphate reaction (ISR), in hardened concrete is the use of mineral additions. This pathology is due to the formation of expansive ettringite (delayed ettringite formation - DEF) inside the material and is very difficult to deal with, because presently there is no efficient method to repair concrete structures affected by DEF. Hence, there is an urgent need to find preventive methods that may enable the inhibition of DEF in new constructions. Nowadays, its recommended the use of mineral additions to sustain this type of degradation. Moreover, their effect depends on the chemical and mineralogical composition and also the cement replacement. The research work presented in this paper deals with the influence of limestone filler, a type I mineral addition, in the inhibition of DEF (Santos Silva et al., 2010a, 2010b), and is part of an extensive study to elucidate the role that the mineral additions have in the mechanism of inhibition of DEF in concrete. For this purpose different concrete mixes were produced by using the same cement type (CEM I 42.5Ra with 3.11% SO3 and 6.4% C3A) and water/cement ratio (0.45), incorporating different amounts of mineral additions, like fly ash, metakaolin, blast-furnace slag, silica fume and limestone filler. The filler influence was followed by expansion and microstructure evaluation of concrete mix at several ages. These studies showed an interesting behaviour of limestone filler, which motivated new concrete formulations with different cement types (CEM I 42.5Rb and CEM I 52.5) that differ in SO3 and C3A contents, in order to investigate its influence in development of DEF. This research includes also a concrete composition with a cement type II (CEM II A-L 42.5R). The results obtained were compared and the conclusions were extracted. It was found that the concrete mixes with limestone filler showing higher expansions than the control composition. According to these results it seems that the limestone filler does not inhibit rather it promotes the expansion due to DEF. Thus, for concretes subjected to high temperatures in early ages, the limestone filler is not adequate to sustain DEF development rather it may even increase the expansion behaviour in concrete mixes. According to these findings, it was proposed that the ISR recommendations must prohibit this kind of mineral addition.
Year: 2011
Number Pages:
7.
Author(s): Santos Silva, A.; Soares, D.; Matos, L.; Salta, M. M.; Gonçalves, A.; Ribeiro, A. C.; Pavoine, A.; Divet, L.
Editor: Instituto de Ciencias de la Construcción "Eduardo Torroja"
Keywords: Microstructure; Mineral additions; Limestone filler; Def; Isr
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Mitigation of Internal Expansive Reaction: the role of Tungsten Mine Sludge
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 sulphatic 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
Year: 2011
Number Pages:
6p.
Author(s): Sousa, S.; Santos Silva, A.; Velosa, A.; Gameiro, A.; Rocha, F.
Editor: Escola de Engenharia da Universidade do Minho
Keywords: Tungsten mine sludge; Mitigation; Delayed ettringite formation; Alkali-silica reaction
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Modeling the start of the expansion due to alkali silica reaction in concrete
Service life of a concrete affected by alkali-silica reactions (ASR) is the age at which expansion is no longer allowed for normal use of a structure; such expansion level depends on the application. Once the induction period ends, the expansion proceeds quickly. Thus, in the present study, the service life was approached by the induction time. Induction time is an abstract concept, its formulation depending on the model considered (additive, constant time in the diffusion model, or the abscissa of intersection of time axis by a tangent to the expansion curve at the inflexion point, in the nucleation and growth model). Mortar bars were made with Tagus river reactive aggregate according the ASTM C 1260 procedure (expansion of bars immersed in NaOH 1M) implemented at temperatures of 80, 70, 60, 50 and 37ºC, to model expansion at constant alkalinity, considering the aggregate reactivity and temperature as variables. The results show that the data has enough precision for a kinetic study. Two kinetic models were considered to fit the data, selecting one of which for further improvement, using the wide information basis on the ASR. The effects of the factors temperature, alkalinity and humidity assumed models referred to in literature, or obtained by regression both of kinetic parameters for each isothermal curve and their temperature coefficients of Arrhenius plots. The correlations obtained allow estimating the strain after the induction period, for any value of the mentioned factors, under laboratory conditions. The model estimates at ca 37ºC were compared with experimental data in the same setup and this temperature. The induction time prediction was satisfactory, but further expansion development pattern was different. The model was tentatively applied to a case reported in literature. Results match, but are affected by significant errors, some improvements being referred to improve accuracy.
Year: 2011
Number Pages:
17p.
Author(s): Gonzalez, L.; Santos Silva, A.; Soares, D.; Jalali, S.
Editor: lnec
Keywords: Service life; Prevision; Reaction start; Aar
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Natural consolidation of ancient historic buildings mortars submitted to humid and marine environment: a microscopic study
Ancient historical buildings are important features of the history, culture and development of a country and its people. This study presents the results of chemical, physical and microstructural characterization performed on mortars in order to assess their durability and good performance in a marine and humid environment, The mortars are collected in two historical monuments in Lisbon region, the Santa Marta Fortress (SM) in the coast line Lisboa-Cascais (XVII century), and the Defence Wall of Lisbon (M), constructed and reconstructed during many centuries, but with zones dated from the roman period to which the analysed samples belong. This edification, approximately 2 km long, was, during centuries, the only defence of the city and is scarcely visible nowadays due to several constructions and changes carried out along the time. The microstrutural characterization was done by optical and scanning electronic microscopy to identify the binder and aggregate types, reaction products and porosity. The microstructural observation reveals that all mortars have the pores normally fulfilled with reaction products, etringite in the SM mortars and calcium carbonate and phosphate in M mortars. Moreover, reaction rims are evident around some aggregates, suggesting the occurrence of pozzolanic reactions between aggregates and the calcitic binder that creates neoformation products, such as calcium-silico-aluminates, which seems be, besides the pores filling, the responsible for the resistance and cohesion of these ancient mortars submitted to aggressive humid environments.
Year: 2011
Number Pages:
15p.
Author(s): Borges, C.; Santos Silva, A.; Veiga, M. R.
Editor: ZAG, Slovenian National Building and Civil Engineering Institute
Keywords: Tga-dta; Xrd; Microscopy; Marine environment; Ancient lime mortars
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Petrographic characterization of granitic aggregates.
Granitic rocks are widely used as aggregates for concrete in Portugal. Although this type of rock is known in some countries to be non-potentially reactive to alkalis, there are reported cases of alkali-silica reaction related to granitic aggregates. As defined by the Portuguese specification LNEC E 461, the petrographic analysis is the first to be carried out when aggregates of unknown performance need to be characterized. The characterization is based on the determination of the percentage of reactive forms of silica in order to classify the aggregate as innocuous or as potentially reactive, according to classes similar to those defined in RILEM AAR-1. This assessment is followed by the mortar bar test (ASTM C 1260 or RILEM AAR-2) when the aggregate is classified in Class II or III. The local experience is that some of the granitic aggregates classified as innocuous by RILEM AAR-2 show a field performance different from that predicted by the tests. Therefore, a research project is being carried out in which systematic concrete prism tests (RILEM AAR-3 and RILEM AAR-4.1) are used to validate the results obtained by petrography and to establish which laboratory test(s) is(are) the most accurate for the assessment of the alkali reactivity of granites. In the present work, the first results of the research are presented, aiming to contribute to the reformulation of the national specification and to establish a possible correlation among the results from different methods.
Year: 2011
Number Pages:
9p.
Author(s): Ramos, V.; Fernandes, I.; Noronha, F.; Santos Silva, A.
Editor: ZAG, Slovenian National Building and Civil Engineering Institute
Keywords: Asr; Expansion tests; Petrographic characterization; Granitic aggregates
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Phase and microstructural characterization of lime-MK blended mixes
N/A
Year: 2011
Number Pages:
6p.
Author(s): Gameiro, A.; Santos Silva, A.; Veiga, M. R.; Velosa, A.
Editor: Escola de Engenharia da Universidade do Minho
Keywords: Sem; Lime; Pozzolan; Metakaolin
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Books
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Materiais de interesse histórico que constroem o património edificado: Correlações, usos, paisagens
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.
Year: 2022
Number Pages:
218p..
Author(s): Veiga, M. R.; Santos Silva, A.; Menezes, M.
: Cadernos do Arquivo Municipal
Editor: Câmara Municipal de Lisboa
Volume:
Vol. II, Nº 17.
Keywords: Calçada Portuguesa; Ouro Preto, Brasil; Baixa Pombalina; Mansardas; Fábrica de cerâmica Lusitânia; Lisboa; Mármore; Raul Lino; Azulejo; Património; Materiais de construção
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On the origin of majolica azulejos production in Portugal. nº 2 - vol II.
Vários
Year: 2019
Number Pages:
97p.
Author(s): Pais, A.; Mimoso, J.; Rosmaninho, R.; Esteves, L.; Morais Pereira, S.; Antunes, M.; Cardoso, A.; Mirão, J.; Marques, A.; Ferreira, M.; Candeias, A.; Valona, R.; Morna, T.; Simões, J.
: Estudos em Cerâmica Vidrada Patrimonial
Editor: LNEC
Keywords: PT; Physical-chemical characterization; Azulejo; Manufacture; Glazed ceramics; Historic heritage
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Characterization of decorative Portuguese gypsum plasters from the 19th and 20th centuries: the case of the Bolsa Palace in Oporto
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.
Year: 2012
Number Pages:
141-151pp.
Author(s): Freire, T.; Santos Silva, A.; Veiga, M. R.; Brito, J.
Editor: Springer
Volume:
Volume 7, RILEM Bookseries.
Keywords: Capillary absorption; Microscopy; Tga-dta; Xrd; Characterisation; Gypsum plasters
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Diagnosis, characterization and restoration of the internal renders of Santíssimo Sacramento church in Lisbon
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.
Year: 2012
Number Pages:
175-194pp.
Author(s): Santos Silva, A.; Borsoi, G.; Veiga, M. R.; Fragata, A.; Tavares, M.; Llera, F.; Barreiros, B.; Teixeira, T.
Editor: Springer
Volume:
Volume 7, RILEM Bookseries.
Keywords: Pigments; Stuccos; Mortars; Plasters
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AS REACÇÕES EXPANSIVAS INTERNAS NO BETÃO. Prevenção dos riscos e gestão das estruturas afectadas
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.
Year: 2010
Number Pages:
143.
Author(s): Santos Silva, A.; Gonçalves, A.; Divet, L.; Pavoine, A.; Germain, D.; Appleton, J.
Editor: LNEC
Keywords: Reparação; Modelação; Gestão; Prevenção; Def; Ras; Betão; Reacções expansivas
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Capítulo de Livro
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Analysis of the behavior of original air lime mortars used in structural brick masonry walls of ancient buildings
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.
Year: 2023
Number Pages:
15p..
Author(s): Candeias, P.; Ferreira, J.; Santos Silva, A.; Veiga, M. R.; Mera Marques, A.
: Conservation and Restoration of Historic Mortars and Masonry Structures
Editor: Springer
Keywords: Characterization tests; Air lime mortars; Structural brick masonry walls; Ancient buildings; Conservation and rehabilitation
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CDW as sources of CO2 absorption
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.
Year: 2023
Number Pages:
243-257pp..
Author(s): Martins, I. M.; Santos Silva, A.; Veiga, M. R.; Infante Gomes, R.; Bastos, D.; Pederneiras, C.; Farinha, C.
: Proceedings of the V International Conference Progress of Recycling in the Built Environment
Editor: RILEM
Volume:
RILEM Proceedings PRO 137.
Keywords: Recycled aggregates; Forced carbonation; CO2 absorption; CDW
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Characterization of mortars and concretes from the Mirante da Quinta da Azeda, Setúbal (Portugal). A case study from the beginning of the 20th century
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.
Year: 2023
Number Pages:
243-257pp..
Author(s): Velosa, A.; Veiga, M. R.; Santos Silva, A.; Lopes dos Santos, A. R.; Almeida, L.
: Conservation and Restoration of Historic Mortars and Masonry Structures
Editor: Springer
Keywords: Portugal; Characterization; Concrete; Mortar; 20th century
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Evaluation of the hygroscopic and CO2 capture capacities of earth and gypsum-based plasters
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.
Year: 2023
Number Pages:
207-215pp..
Author(s): Faria, P.; Gomes, I.; Santos Silva, A.; Santos, T.
: Conservation and Restoration of Historic Mortars and Masonry Structures
Editor: Springer
Keywords: Mortar; Indoor air quality; Hygroscopicity; Gypsum; Clayey earth; CO2 capture
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Os revestimentos e os acabamentos do Centro Histórico de Coimbra. Um contributo para o seu estudo
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.
Year: 2017
Number Pages:
49-74pp.
Author(s): Catarino, L.; Gil, F.; Duarte, T.; Veiga, M. R.; Santos Silva, A.
Editor: Almedina
Keywords: Cal calcítica; Cal dolomítica; Argamassas; Caracterização; Estratigrafia; Centro Histórico de Coimbra; Revestimentos
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Tese de Doutoramento
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Revestimentos nanoestruturados para protecção de liga de alumínio
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.
Year: 2012
Number Pages:
256.
Author(s): Fontinha, I. R.
Keywords: Corrosão; Liga de alumínio; Sol-gel; Revestimentos híbrido nanoestruturados
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Passivação do aço inoxidável no betão
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.
Year: 2009
Author(s): Correia, M. J.
Keywords: Corrosão; Propriedades semicondutoras; Filme de passivação; Aço inoxidável
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Dissertação de Mestrado
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Caracterização de argamassas tradicionais e históricas de edifícios religiosos do Alentejo
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.
Year: 2009
Author(s): Adriano, P.
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Estabilidade stabilidade de taludes em rochas silto-argilosas
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.
Year: 2008
Author(s): Matos, L.
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Relatório Científico
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Estudos microestruturais de amostras de argamassa, betão e agregados - Projecto PIP LNEC 2009-2012 Materiais com interesse histórico. Durabilidade e caracterização
N/A
Year: 2011
Number Pages:
77pp.
Author(s): Menezes, P.; Santos Silva, A.; Menezes, A. P.
Editor: LNEC
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Abordagem sobre a evolução na construção de pontes metálicas
N/A
Year: 2010
Number Pages:
31pp.
Author(s): Perneta, H.
Editor: LNEC
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Caracterização química, mineralógica e microestrutural das argamassas da Villa Romana de Pisões Beja
N/A
Year: 2010
Number Pages:
83pp.
Author(s): Borsoi, G.; Santos Silva, A.
Editor: LNEC
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ESTUDO DAS REACÇÕES ÁLCALIS-SÍLICA EM BETÕES COM AGREGADOS RECICLADOS
A presente comunicação descreve alguns resultados da primeira fase de um trabalho experimental sobre as reacções álcalis-sílica (RAS) em betões com agregados reciclados (BAR). As RAS surgem no betão com agregados convencionais (BAC) devido à combinação de sílica reactiva, álcalis e humidade em quantidades suficientes. Nestas condições, ao longo do tempo, desenvolve-se um gel expansivo que provoca a degradação das estruturas com redução da sua durabilidade. A possível ocorrência das RAS nos BAR serviu de motivação aos autores para o desenvolvimento de um estudo relativo à análise destas reacções em betões com incorporação total e parcial de agregados recicla-dos (AR). Serão analisadas em particular variações no grau de reactividade aos álcalis, no tipo de cimento e de cura empregues tendo em vista verificar se a incorporação de AR nos betões torna ou não mais dano-sa a problemática da RAS, comparativamente aos BAC. Descrevem-se também nesta comunicação alguns aspectos, observados na bibliografia, de diferenças entre a análise das RAS nos BAR e nos BAC.
Year: 2009
Number Pages:
10.
Author(s): Santos, M. B.; Brito, J.; Santos Silva, A.
Keywords: Durabilidade; Degradação; Reacções álcalis-sílica; Betões com agregados reciclados
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Inter-Laboratory tests of anodized aluminium testing methods - Statistical analysis determination of repeatability and reproducibility
N/A
Year: 2009
Number Pages:
58pp.
Author(s): Garcia, N.; Fontinha, I. R.
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Artificial weathering of bronze patinas - Selection of test conditions
In this report, results of a study carried out with the objective of establishing the conditions for artificial weathering practice adequate to patinated bronze with applied conservation treatments are presented. The work developed is part of the research activities that have been carried out in the Metallic Materials Division for the European project ARTECH, integrated in the working group JRA1: Development and evaluation of new treatments for the conservation-restoration of outdoor stone and bronze monuments.
Year: 2008
Number Pages:
28pp.
Author(s): Fontinha, I. R.
Keywords: Bronze; Weathering
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Caracterização química, mineralógica e microestrutural de amostras de revestimentos exteriores do Palácio do Lidador em Beja
O presente trabalho insere-se no estudo Desenvolvimento de métodos de caracterização química e microestrutural e de diagnóstico da patologia dos materiais, Procº 0204/11/16163, incluído no projecto de investigação programada do LNEC para 2005 2008 Qualidade dos Materiais. Foram analisadas amostras de revestimentos exteriores provenientes do Palácio do Lidador em Beja, que foram disponibilizadas na sequência de trabalhos empreendidos pela Câmara Municipal de Beja que contemplaram a recuperação, consolidação e preenchimento de lacunas e reintegração cromática dos revestimentos e acabamentos exteriores do edifício. O trabalho consistiu na caracterização de cinco revestimentos exteriores, nomeadamente com a realização de análises estratigráficas de todas as amostras e de análise química, mineralógica e microestrutural [1] das argamassas de duas das amostras. Neste Relatório incluiu-se a descrição das amostras e o modo de preparação para os ensaios, apresentam-se os resultados obtidos e faz-se a sua apreciação.
Year: 2008
Number Pages:
36pp.
Author(s): Santos Silva, A.; Menezes, A. P.; Barracha, L.; Couto, S.
Keywords: Caracterização química; Revestimentos exteriores; Palácio do lidador; Microestrutural; Mineralógica; Beja
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Estudo da influência de adições minerais na inibição da formação de etringite retardada no betão
Nos últimos anos tem-se verificado um aumento do número de casos de estruturas de betão afectadas por reacções químicas expansivas de origem interna, nomeadamente pela reacção sulfática interna (RSI), que se caracteriza pela formação de etringite expansiva, em particular a que está associada com a formação de etringite retardada (DEF). Esta reacção é muito difícil de combater, não existindo actualmente um método eficaz de reparação de estruturas degradas por RSI. Tendo em conta este facto, existe uma necessidade premente de encontrar métodos preventivos que possibilitem a inibição da formação de DEF em novas construções. A primeira parte deste trabalho apresenta os resultados de um estudo a longo prazo sobre a influência das cinzas volantes e do metacaulino no desenvolvimento da RSI, em particular na inibição da formação da DEF. Para tal, betões com diferentes razões água/cimento (A/C) e tipo de brita foram produzidos e sujeitos a tratamento térmico. Medidas de expansão dos vários betões foram efectuadas durante um período de 1000 dias após o que se procedeu à sua caracterização microestrutural por MEV/EDS. Os resultados mostram que tanto as cinzas volantes como o metacaulino parecem inibir a RSI, e que a natureza mineralógica dos agregados igualmente desempenha um papel importante na reacção bem como a razão A/C. Face a estes resultados, foi programada a segunda parte do trabalho com o objectivo de determinar a quantidade mínima a partir da qual a presença de adição inibe a DEF. Foi ainda testado também um outro tipo de adição filer calcário. Para tal, betões de agregado silicioso com menores percentagens de adição foram produzidos em condições idênticas às da primeira parte do trabalho. Os resultados obtidos parecem mostrar que o mecanismo de inibição da RSI é semelhante para o metacaulino e cinzas volantes, e que 10% de metacaulino ou 15% de cinzas volantes parece ser suficiente para inibir a DEF, enquanto que o filer calcário não parece inibir esta reacção expansiva.
Year: 2008
Number Pages:
162pp.
Author(s): Soares, D.; Santos Silva, A.
Keywords: Retardada no betão; Formação de etringite; De adições minerais; Estudo da influência
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Relatório final de actividades da bolseira de investigação Patrícia Adriano no projecto FCT CATHEDRAL
No âmbito do projecto financiado pela FCT (Projecto CATHEDRAL Caracterização e Conservação de Argamassas Tradicionais e Históricas de Edifícios Religiosos do Alentejo POCI/HEC/57915/2004), em que participam o Laboratório Nacional de Engenharia Civil (LNEC), a Universidade de Évora e o Instituto Português do Património Arquitectónico (antigo IPPAR) e a Faculdade de Ciências da Universidade de Lisboa (FCUL), a Bolseira de Investigação Patrícia Alexandra Alves Pedro Adriano analisou argamassas provenientes de quatro monumentos do Alentejo e pertencentes a períodos históricos diferentes: 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).
Year: 2008
Number Pages:
15pp.
Author(s): Adriano, P.; Santos Silva, A.
Keywords: Edifícios religiosos; Conservação de argamassas; Cathedral; No projecto fct
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Weathering of treatments for bronze conservation - Results of natural and artificial weathering
Neste relatório apresentam-se os resultados dos ensaios de envelhecimento natural e artificial de tratamentos para a conservação de bronze patinado, realizados com o objectivo de avaliar a eficácia dos sistemas aplicados. Os produtos de conservação em estudo foram desenvolvidos no âmbito do projecto europeu Eu-ARTECH. O trabalho desenvolvido foi realizado no Núcleo de Materiais Metálicos, durante 2008, no âmbito projecto Eu-ARTECH, inserido no grupo de trabalho JRA1: Development and evaluation of new treatments for the conservation-restoration of outdoor stone and bronze monuments.
Year: 2008
Number Pages:
36pp.
Author(s): Fontinha, I. R.; Salta, M. M.
Keywords: Produtos; Sistemas aplicados; Avaliar a eficácia; Ensaios
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Effect of inorganic content on the performance of anticorrosive hybrid sol-gel coated EN AW-6063 alloy
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.
Year: 2011
Author(s): Fontinha, I. R.; Salta, M. M.; Zheludkevich, M.; Ferreira, M. G. S.
Editor: Materais 2011 - SPM
Keywords: Aluminium; Corrosion; Sol-gel; Hybrid coating
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Characterization of the concrete alkali reactivity of granitoid and dolomitic aggregates
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.
Year: 2010
Number Pages:
1.
Author(s): Sabino, N.; Santos Silva, A.; Menezes, A. P.; Moita, P.; Candeias, A.; Mirão, J.
Editor: Department of Mineralogy, Geochemistry and Pterology, University of Szeged
Keywords: Dolomites; Granites; Alkali reactivity; Asr
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