Many geoscience fieldworks are not aligned with the curriculum contents reflecting the need to de... more Many geoscience fieldworks are not aligned with the curriculum contents reflecting the need to develop more research related to the outdoor learning environment. The purpose of the study was to verify if a fieldwork organized in accordance with Orion's model (1993), could be assumed as an integral part of formal school science curricula. A fieldwork has been carried with a sample of 115 secondary science students from a rural school in Portugal. A mixed research method was carried out. Short questionnaires were applied to students and to a participant observer, and the researcher wrote reports. Evidences indicated the relevance of geological fieldworks for geoscience education. This study highlighted the relevance of fieldwork as an integral component of the formal curriculum.
Recognizing the relevance that fieldwork and field trips have in the teaching of geosciences and ... more Recognizing the relevance that fieldwork and field trips have in the teaching of geosciences and related learning processes, this study presents two geological fieldwork studies that were established with Portuguese secondary school students. Both studies were focused on geoscience content knowledge, and attempted to increase environmental awareness and highlight geoheritage values. Following the Orion model (1993), the fieldwork was established in three stages (the preparatory unit, field trip, and summary unit), which facilitated its implementation and subsequent assessment. Both studies took place in regions in the north of Portugal. One field trip was undertaken at the coastal area of Vila do Conde and the other on the left bank of the Minho River, in Monçã o. Since a mixed methods research design was applied, different data types were collected and triangulated. Results indicate that the fieldwork was effective in terms of facilitating the development of conceptual knowledge, motivation, and diverse competencies. These results contribute to the recognition of fieldwork as an important strategy in geoscience education and geoscience awareness. The study also highlights that the relevance of fieldwork should be recognized by Portuguese curriculum designers and should be incorporated in the Portuguese science curriculum.
... apoio na realização dos ensaios e obtenção de dados de microssonda electrónica. À Professora ... more ... apoio na realização dos ensaios e obtenção de dados de microssonda electrónica. À Professora Doutora Ana Margarida Neiva, agradeço a ajuda preciosa na ... A Dra. Daniela Silva e ao CEMUP, quero demonstrar o reconhecimento pelo apoio na ... m Page 8. Agradecimentos IV ...
14th SGEM GeoConference on SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, 2014
ABSTRACT Volcanic rocks have been found to be the cause of concrete deterioration in several coun... more ABSTRACT Volcanic rocks have been found to be the cause of concrete deterioration in several countries (Argentina, Iceland, Japan, New Zealand and Turkey), due to the occurrence of alkali-silica reactions. Alkali-silica reaction (ASR) is a deterioration phenomenon that occurs between alkaline (Na+ and K+) and hydroxyl (OH-) ions in the cement and certain reactive forms of silica in the aggregates. The reactivity of volcanic rocks is usually associated with the presence of dacitic or rhyolitic volcanic glass (SiO2>62-65%), altered minerals and the occurrence of free silica forms such as opal, tridymite and cristobalite. The characterization of the reactivity of Azores volcanic aggregates has been implemented through the research project ReAVA (Characterization of Potential Reactivity of the Volcanic Aggregates from the Azores Archipelago: Implications on the Durability of Concrete Structures) that comprises mainly the petrographic assessment of the aggregates. The petrographic study of the aggregates is complemented by petrographic examination of samples from large structures in order to confirm the potential reactivity of the aggregates. In Santa Maria Island a program was carried out to produce thin sections from: (1) rock samples of two quarries of the island and (2) concrete core samples from the local airport pavement. The petrographic examination and the geochemical analyses of the two rock samples showed a significant alteration of both rocks. The examination of the concrete thin sections showed that the sand fraction is mainly composed by volcanic glass and that the cement paste has almost completely been replaced by an alkali-silica gel, as confirmed by scanning electron microscopy.
Petrography is used as a first step in assessing the potential AAR-susceptibility of concrete agg... more Petrography is used as a first step in assessing the potential AAR-susceptibility of concrete aggregates. When an aggregate is classified as innocuous further testing is usually not mandatory. Thus, it is important to be aware of the complex petrographic characteristics of reactive aggregates, without which there is a risk that deleterious aggregates will be used with no special care. This paper reports on intriguing evidence from Norwegian and Portuguese field concretes and specimens from accelerated testing. ASR-gels formed in association with medium-grained granitic and quartzitic aggregates, characterised by strain free quartz and stable grain boundaries. ASR-gel formation sites preferably occurred in contact with micas and feldspars. Conversely, granitic mylonites characterised by annealed microcrystalline quartz and very low mica contents were mainly innocuous. The results suggest that quartz size in many cases is of subordinate importance, whilst the reactivity seems partly controlled by dissolution of feldspars and micas, perhaps also involving catalytic effects.
Engineering Geology for Society and Territory - Volume 5, 2014
ABSTRACT Volcanic rocks have been found to be potentially alkali-reactive in a number of countrie... more ABSTRACT Volcanic rocks have been found to be potentially alkali-reactive in a number of countries, including Japan, New Zealand, Iceland and Turkey. In order to characterize the potential reactivity of the volcanic rocks in Azores a project is being carried out, under the support of the Azores Government: the ReAVA Project – “Characterization of Potential Reactivity of the Volcanic Aggregates from the Azores Archipelago: Implications on the Durability of Concrete Structures”. This project comprises mainly: (1) petrographic assessment of the aggregates, (2) assessment of their performance in expansion tests and (3) site inspection of existing large concrete structures. This study has also the support of the IMPROVE Project – “Improvement of Performance of Aggregates in the Inhibition of Alkali- Aggregate Reactions in Concrete”, aiming to minimize the occurrence of alkali aggregate reaction (AAR) in Portugal. The Azorean rocks used as aggregates are mainly basalts and some trachytes. The reactivity of this kind of rocks is usually associated with the presence of volcanic glass, altered minerals and SiO2 content of the rock. The petrographic examinations of the rocks confirmed that one of the basaltic samples contains volcanic glass. The occurrence of microcrystalline quartz as a secondary product filling the interstices of the trachyte sample was confirmed by scanning electron microscope. The results of the concrete expansion test RILEM AAR-3 showed an increasing expansion starting on 140 days and continued to grow after two years of laboratory testing, but below the limit of 0.05% recommended for this method.
Engineering Geology for Society and Territory - Volume 2, 2015
The action of the geodynamic agents (external and/or internal), or even the human activities, can... more The action of the geodynamic agents (external and/or internal), or even the human activities, can cause changes in the structure of a slope that may result in an imbalance between the internal and the external forces acting on the ground. The aim of this study is the analysis of the stability of a natural rock slope located along the Távora river, Northern Portugal. The geological mapping of the area and the use of stereonet to determine the main sets of joints were the starting point for the performed analysis. It was complemented with the study of different factors regarding the stability of the rock mass. The geomechanical characterization of the rock mass was also used, with the application of Bieniawski and Romana ratings. The methodologies applied proved to be a simple but effective way to describe the potential behavior of the rock mass with respect to the probability of occurrence of slope movements.
Engineering Geology for Society and Territory - Volume 5, 2014
In Portugal, volcanic rocks are commonly used as concrete aggregates for concrete in Madeira and ... more In Portugal, volcanic rocks are commonly used as concrete aggregates for concrete in Madeira and Azores Islands and in a lesser extent in the Mainland. Nonetheless, the information about the potential alkali-silica reactivity of Portuguese volcanic rocks is rather scarce. In order to fulfill this lack of information and in the scope of a Portuguese research project, four volcanic aggregates from the Portuguese Mainland and Madeira Archipelago were investigated. For this purpose petrographic characterization (polarizing microscopy complemented by bulk chemical analysis and scanning electron microscopy with energy dispersive detector) along with expansion laboratory tests were carried out. In this paper, results of the investigation are presented aiming to establish a possible correlation among the results from the used methods.
Concrete is one of the most widely used building materials since the nineteenth century. The manu... more Concrete is one of the most widely used building materials since the nineteenth century. The manufacture of concrete includes the binder (cement), aggregates, water and possible additives. Although very versatile and durable, in the early 1900s, it was recognized that concrete can deteriorate and in consequence, compromise the durability and good functioning of the structures. From the many different damage mechanisms that can originate the deterioration of concrete, alkali-silica reaction (ASR) is the one that involves the aggregates. Aggregates constitute about three-quarter of the volume of concrete, and therefore their physical and chemical properties need to be correctly assessed before their use in concrete. Since the 1940s, considerable research has been developed to determine which components of the rocks and minerals contribute to the chemical reaction involved in this process of deterioration. However, a lot still remains to be understood. In the present article, an introduction to the subject is made, focusing mainly on the mechanisms and on the manifestations of the ASR.
U n c o r r e c t e d P r o o f Karl Ritz • Lorna Dawson • David Miller Editors Criminal and Envi... more U n c o r r e c t e d P r o o f Karl Ritz • Lorna Dawson • David Miller Editors Criminal and Environmental Soil Forensics Ritz_FM.indd iii 9/30/2008 2:48:29 AM U n c o r r e c t e d P r o o f
ABSTRACT A monitoring system has been detecting progressive displacements in Fagilde dam, complet... more ABSTRACT A monitoring system has been detecting progressive displacements in Fagilde dam, completed in 1984. Site inspection revealed the existence of random cracking, surface discoloration, and superficial dissolution of cement in the spillway surfaces and in the upstream face of the dam. The macroscopic signs of deterioration, which could be due to different mechanisms, showed an uneven distribution in the exposed surfaces of the structure. Crushed limestone and alluvial siliceous sand were used as aggregates. Alkali–aggregate reaction was considered to be the likely cause of concrete distress. In order to investigate the causes of cracking and of the movements registered in the wall, drill core sampling was performed and the concrete investigated for the occurrence of expansive reactions. Concrete petrography was complemented by other tests in order to assess the probable evolution of the reactions in the structure in the near future. Residual expansion tests, soluble alkalis evaluation, and unconfined compression tests were carried out. Alkali–aggregate reactions and internal sulfate reaction were considered to be the main causes of damage in the concrete. In this study, microscopy showed to be an essential tool in the identification of the main causes of deterioration.
Many geoscience fieldworks are not aligned with the curriculum contents reflecting the need to de... more Many geoscience fieldworks are not aligned with the curriculum contents reflecting the need to develop more research related to the outdoor learning environment. The purpose of the study was to verify if a fieldwork organized in accordance with Orion's model (1993), could be assumed as an integral part of formal school science curricula. A fieldwork has been carried with a sample of 115 secondary science students from a rural school in Portugal. A mixed research method was carried out. Short questionnaires were applied to students and to a participant observer, and the researcher wrote reports. Evidences indicated the relevance of geological fieldworks for geoscience education. This study highlighted the relevance of fieldwork as an integral component of the formal curriculum.
Recognizing the relevance that fieldwork and field trips have in the teaching of geosciences and ... more Recognizing the relevance that fieldwork and field trips have in the teaching of geosciences and related learning processes, this study presents two geological fieldwork studies that were established with Portuguese secondary school students. Both studies were focused on geoscience content knowledge, and attempted to increase environmental awareness and highlight geoheritage values. Following the Orion model (1993), the fieldwork was established in three stages (the preparatory unit, field trip, and summary unit), which facilitated its implementation and subsequent assessment. Both studies took place in regions in the north of Portugal. One field trip was undertaken at the coastal area of Vila do Conde and the other on the left bank of the Minho River, in Monçã o. Since a mixed methods research design was applied, different data types were collected and triangulated. Results indicate that the fieldwork was effective in terms of facilitating the development of conceptual knowledge, motivation, and diverse competencies. These results contribute to the recognition of fieldwork as an important strategy in geoscience education and geoscience awareness. The study also highlights that the relevance of fieldwork should be recognized by Portuguese curriculum designers and should be incorporated in the Portuguese science curriculum.
... apoio na realização dos ensaios e obtenção de dados de microssonda electrónica. À Professora ... more ... apoio na realização dos ensaios e obtenção de dados de microssonda electrónica. À Professora Doutora Ana Margarida Neiva, agradeço a ajuda preciosa na ... A Dra. Daniela Silva e ao CEMUP, quero demonstrar o reconhecimento pelo apoio na ... m Page 8. Agradecimentos IV ...
14th SGEM GeoConference on SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, 2014
ABSTRACT Volcanic rocks have been found to be the cause of concrete deterioration in several coun... more ABSTRACT Volcanic rocks have been found to be the cause of concrete deterioration in several countries (Argentina, Iceland, Japan, New Zealand and Turkey), due to the occurrence of alkali-silica reactions. Alkali-silica reaction (ASR) is a deterioration phenomenon that occurs between alkaline (Na+ and K+) and hydroxyl (OH-) ions in the cement and certain reactive forms of silica in the aggregates. The reactivity of volcanic rocks is usually associated with the presence of dacitic or rhyolitic volcanic glass (SiO2>62-65%), altered minerals and the occurrence of free silica forms such as opal, tridymite and cristobalite. The characterization of the reactivity of Azores volcanic aggregates has been implemented through the research project ReAVA (Characterization of Potential Reactivity of the Volcanic Aggregates from the Azores Archipelago: Implications on the Durability of Concrete Structures) that comprises mainly the petrographic assessment of the aggregates. The petrographic study of the aggregates is complemented by petrographic examination of samples from large structures in order to confirm the potential reactivity of the aggregates. In Santa Maria Island a program was carried out to produce thin sections from: (1) rock samples of two quarries of the island and (2) concrete core samples from the local airport pavement. The petrographic examination and the geochemical analyses of the two rock samples showed a significant alteration of both rocks. The examination of the concrete thin sections showed that the sand fraction is mainly composed by volcanic glass and that the cement paste has almost completely been replaced by an alkali-silica gel, as confirmed by scanning electron microscopy.
Petrography is used as a first step in assessing the potential AAR-susceptibility of concrete agg... more Petrography is used as a first step in assessing the potential AAR-susceptibility of concrete aggregates. When an aggregate is classified as innocuous further testing is usually not mandatory. Thus, it is important to be aware of the complex petrographic characteristics of reactive aggregates, without which there is a risk that deleterious aggregates will be used with no special care. This paper reports on intriguing evidence from Norwegian and Portuguese field concretes and specimens from accelerated testing. ASR-gels formed in association with medium-grained granitic and quartzitic aggregates, characterised by strain free quartz and stable grain boundaries. ASR-gel formation sites preferably occurred in contact with micas and feldspars. Conversely, granitic mylonites characterised by annealed microcrystalline quartz and very low mica contents were mainly innocuous. The results suggest that quartz size in many cases is of subordinate importance, whilst the reactivity seems partly controlled by dissolution of feldspars and micas, perhaps also involving catalytic effects.
Engineering Geology for Society and Territory - Volume 5, 2014
ABSTRACT Volcanic rocks have been found to be potentially alkali-reactive in a number of countrie... more ABSTRACT Volcanic rocks have been found to be potentially alkali-reactive in a number of countries, including Japan, New Zealand, Iceland and Turkey. In order to characterize the potential reactivity of the volcanic rocks in Azores a project is being carried out, under the support of the Azores Government: the ReAVA Project – “Characterization of Potential Reactivity of the Volcanic Aggregates from the Azores Archipelago: Implications on the Durability of Concrete Structures”. This project comprises mainly: (1) petrographic assessment of the aggregates, (2) assessment of their performance in expansion tests and (3) site inspection of existing large concrete structures. This study has also the support of the IMPROVE Project – “Improvement of Performance of Aggregates in the Inhibition of Alkali- Aggregate Reactions in Concrete”, aiming to minimize the occurrence of alkali aggregate reaction (AAR) in Portugal. The Azorean rocks used as aggregates are mainly basalts and some trachytes. The reactivity of this kind of rocks is usually associated with the presence of volcanic glass, altered minerals and SiO2 content of the rock. The petrographic examinations of the rocks confirmed that one of the basaltic samples contains volcanic glass. The occurrence of microcrystalline quartz as a secondary product filling the interstices of the trachyte sample was confirmed by scanning electron microscope. The results of the concrete expansion test RILEM AAR-3 showed an increasing expansion starting on 140 days and continued to grow after two years of laboratory testing, but below the limit of 0.05% recommended for this method.
Engineering Geology for Society and Territory - Volume 2, 2015
The action of the geodynamic agents (external and/or internal), or even the human activities, can... more The action of the geodynamic agents (external and/or internal), or even the human activities, can cause changes in the structure of a slope that may result in an imbalance between the internal and the external forces acting on the ground. The aim of this study is the analysis of the stability of a natural rock slope located along the Távora river, Northern Portugal. The geological mapping of the area and the use of stereonet to determine the main sets of joints were the starting point for the performed analysis. It was complemented with the study of different factors regarding the stability of the rock mass. The geomechanical characterization of the rock mass was also used, with the application of Bieniawski and Romana ratings. The methodologies applied proved to be a simple but effective way to describe the potential behavior of the rock mass with respect to the probability of occurrence of slope movements.
Engineering Geology for Society and Territory - Volume 5, 2014
In Portugal, volcanic rocks are commonly used as concrete aggregates for concrete in Madeira and ... more In Portugal, volcanic rocks are commonly used as concrete aggregates for concrete in Madeira and Azores Islands and in a lesser extent in the Mainland. Nonetheless, the information about the potential alkali-silica reactivity of Portuguese volcanic rocks is rather scarce. In order to fulfill this lack of information and in the scope of a Portuguese research project, four volcanic aggregates from the Portuguese Mainland and Madeira Archipelago were investigated. For this purpose petrographic characterization (polarizing microscopy complemented by bulk chemical analysis and scanning electron microscopy with energy dispersive detector) along with expansion laboratory tests were carried out. In this paper, results of the investigation are presented aiming to establish a possible correlation among the results from the used methods.
Concrete is one of the most widely used building materials since the nineteenth century. The manu... more Concrete is one of the most widely used building materials since the nineteenth century. The manufacture of concrete includes the binder (cement), aggregates, water and possible additives. Although very versatile and durable, in the early 1900s, it was recognized that concrete can deteriorate and in consequence, compromise the durability and good functioning of the structures. From the many different damage mechanisms that can originate the deterioration of concrete, alkali-silica reaction (ASR) is the one that involves the aggregates. Aggregates constitute about three-quarter of the volume of concrete, and therefore their physical and chemical properties need to be correctly assessed before their use in concrete. Since the 1940s, considerable research has been developed to determine which components of the rocks and minerals contribute to the chemical reaction involved in this process of deterioration. However, a lot still remains to be understood. In the present article, an introduction to the subject is made, focusing mainly on the mechanisms and on the manifestations of the ASR.
U n c o r r e c t e d P r o o f Karl Ritz • Lorna Dawson • David Miller Editors Criminal and Envi... more U n c o r r e c t e d P r o o f Karl Ritz • Lorna Dawson • David Miller Editors Criminal and Environmental Soil Forensics Ritz_FM.indd iii 9/30/2008 2:48:29 AM U n c o r r e c t e d P r o o f
ABSTRACT A monitoring system has been detecting progressive displacements in Fagilde dam, complet... more ABSTRACT A monitoring system has been detecting progressive displacements in Fagilde dam, completed in 1984. Site inspection revealed the existence of random cracking, surface discoloration, and superficial dissolution of cement in the spillway surfaces and in the upstream face of the dam. The macroscopic signs of deterioration, which could be due to different mechanisms, showed an uneven distribution in the exposed surfaces of the structure. Crushed limestone and alluvial siliceous sand were used as aggregates. Alkali–aggregate reaction was considered to be the likely cause of concrete distress. In order to investigate the causes of cracking and of the movements registered in the wall, drill core sampling was performed and the concrete investigated for the occurrence of expansive reactions. Concrete petrography was complemented by other tests in order to assess the probable evolution of the reactions in the structure in the near future. Residual expansion tests, soluble alkalis evaluation, and unconfined compression tests were carried out. Alkali–aggregate reactions and internal sulfate reaction were considered to be the main causes of damage in the concrete. In this study, microscopy showed to be an essential tool in the identification of the main causes of deterioration.
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Papers by Isabel Fernandes