Analytical characterization of ancient mortars from the archaeological roman site of Pisões (Beja, Portugal)

The analytical characterization of mortar samples from the roman archaeological site of Pisões, located in Southern Portugal, were carried out by means of X-ray diffractometry (XRD), thermogravimetry (TGADTA), optical and electron scanning microscopy (SEM-EDS), potentiometry and combustion analysis. The Pisões archaeological complex includes a villa rustica, characterized by well-preserved mosaics and thermal baths, as well as a mill and a mausoleum. Countryside villae epitomized the Romanization of the Iberian Peninsula for over six centuries (2nd century BCE–4th century CE). Nevertheless, most of the Roman villae identified in Portugal have not yet been systematically explored and studied. This study provides valuable data on the construction materials and techniques used in Roman times in the Iberian Peninsula. The careful selection of raw materials and the use of natural and artificial pozzolanic materials can explain the favourable state of conservation, mechanical strength and long-term durability of these mortars

AVALIAÇÃO DAS PROPRIEDADES GEOQUÍMICAS, MINERALÓGICAS E GEOMECÂNICAS EM PERFIS DE ALTERAÇÃO DE MACIÇOS GRANITÓIDES

O presente trabalho pretende ser um contributo para a caracterização geológico-geotécnica dos solos residuais de rochas granitóides de uma região de clima temperado, a Região do Alentejo, em Portugal. A composição química, mineralógica e textural dos granitóides do Alentejo, bem como de outros granitóides da Península Ibérica, apresentam variações distintas conforme a geologia local. Devido aos diferentes tipos de alteração que ocorrem na formação dos perfis de solos residuais, os produtos finais também serão diversos [Duarte, 2002]. Assim, as propriedades físicas, químicas, mineralógicas e geomecânicas destes solos dependem não só da composição química e mineralógica da rocha mãe, mas também das características geomorfológicas e climatéricas locais [Duarte et al, 2004, 2008]. Para a prossecução do trabalho foram selecionados três locais com perfis de alteração distintos, dentro da Região Alentejo e que se ilustram na Figura 1: i) Perfil de alteração de um granodiorito da Pedreira de Monte das Flores, no Maciço Eruptivo de Évora, com cerca de 8 m de altura; ii) Perfil de alteração de um quartzodiorito da Pedreira de Benafessim, no Maciço Eruptivo de Montemor-o-Novo, com cerca de 10 m de altura; iii) Perfil de alteração de um granito da escavação para o Aterro Sanitário de Arraiolos, no Maciço Granítico do Vimieiro, com cerca de 12 m de altura. Nos três locais selecionados para o estudo foram colhidas amostras de solo residual e respetiva rocha mãe ao longo de cada perfil, com o espaçamento de sensivelmente 1 metro entre amostras, tendo estas sido devidamente acondicionadas e levadas para o laboratório para as submeter à realização de análises químicas e mineralógicas e ensaios físicos e mecânicos. Nos mesmos locais de colheita, foram igualmente determinadas a propriedades físicas “in situ” ao longo de cada perfil, tais como, teor em água no estado natural, peso volúmico húmido e seco, porosidade, entre outras. Os principais objectivos deste trabalho são os seguintes: - conhecer as propriedades geoquímicas, mineralógicas e geomecânicas dos solos residuais de três tipos distintos de rochas granitóides, granito, granodiorito e quartzodiorito; - compreender e relacionar a variabilidade de propriedades físico-químicas ao longo de um perfil de alteração de rochas granitóides em clima temperado; - antecipar o comportamento geotécnico, em tempo real, pelo conhecimento da variação da composição química dos solos residuais. A finalidade deste trabalho passa também pela abordagem aos métodos tradicionais de ensaio para determinação das características químicas e mineralógicas dos solos residuais e respetiva rocha-mãe dos maciços em estudo, recorrendo à análise química por espectometria de fluorescência de raios-X (FRX) e análise mineralógica por difracção de raio-X (DRX). Foram obtidas as várias propriedades físicas e mecânicas, tanto “in situ” como no laboratório, recorrendo para tal, à execução de diferentes ensaios, tais como: análise granulométrica, composição textural, limites de consistência, teor em água (no estado natural), expansibilidade, equivalente de areia, densidade, permeabilidade e teor em matéria orgânica. Faz-se uma comparação entre as principais características (a nível da microestrutura, da macroestrutura, da composição mineralógica, geoquímica e textural) que se desenvolvem ao longo de cada perfil de alteração, assim como do seu comportamento geotécnico expectável, [Blight, 1997]. Apresenta-se uma análise comparativa dos resultados experimentais obtidos nos três perfis de alteração de tipos litológicos distintos (granito, granodiorito e quartzodiorito). É apresentada também a avaliação e evolução das propriedades ao longo de cada perfil, com base nos dados provenientes dos ensaios “in-situ” e laboratoriais efetuados. Este trabalho permite evidenciar a importância de proceder à caracterização geológico-geotécnica dos solos residuais de rochas granitóides dada a vasta extensão de ocorrências destes materiais, não só em Portugal como também noutras regiões do mundo, de modo a determinar a sua aplicação nas diferentes obras de engenharia

Pathway Weathering in Granitoid Rocks from Central Region of Angola: Geochemical and Mineralogical Data

The Central Region of Angola is characterized by the abundance of granitoid rocks, whose weathering “in situ” originated the so-called residual soils. The textural, geochemical and mineralogical properties of these soils depend not only on the chemical composition of parent rock, but mainly on the local climatic and geomorphological characteristics. In the study area, sampling sites were selected, which extend from the region of Kwanza- Norte (Kassenda, Dondo) through Kwanza-Sul (Cangulo, Quibala and Waco Kungo) until the plateau of Huambo, where samples of fresh rock, weathered rock and its residual soil were collected along each weathering profile. Chemical analytical data were determined using X-ray fluorescence (XRF) analysis of the major and minor elements, whereas mineralogical data were determined using X-ray diffraction (XRD), on the samples of rock and on the respective residual soil. The results obtained and their comparative analysis between the sampling sites, as well as along each weathering profile is presented. This paper allows contributing to the knowledge of the geochemical weathering in tropical areas, as is the case of Angola

Soil mineralogical composition effects on the durability of adobe blocks from the Huambo region, Angola

After many years of war, great efforts have been made for the socio-economic development of Angola, particularly in the construction industry. Among the construction techniques, adobe is one of the most used in the province of Huambo, especially by low-income families, which constitute the majority. This technique was established as an intangible heritage in the culture of that population. Huambo province is located in the central region of Angola (Central Plateau). Adobe blocks are building elements with potential degradation by the action of water. Due to the subtropical climate, hot and humid, and geomorphology of the province, located at about 1000–2000 m of altitude and with an extensive river system, these buildings can be vulnerable and may present premature degradation, exacerbated by the lack of knowledge concerning the properties of the geomaterials used and techniques/solutions that allow their stabilization and conservation. This paper aims to present the main results of the study to investigate the influence on adobe performance in regard to the mineralogy and geochemistry of soils used in the production of adobes used in the construction of dwellings. The knowledge gained with this research can support the development of solutions for the common anomalies and problems in this construction, as well as to improve the strength and durability of the adobe units. For this purpose, soil samples were collected and mineralogical, geochemical, and physical tests were performed. Durability and erodibility tests were also performed on selected adobes, following the Geelong method. The results obtained with this research may contribute to the development of the knowledge concerning this sustainable building solution, which has a strong presence in the province of Huambo and neighbouring regions.FCT - UID/GEO/04035/201

Alteração de Rochas Granitóides em Angola.

A Região Central de Angola caracteriza-se pela abundância de rochas granitóides, cuja alteração “in-situ” originou os denominados solos residuais. As propriedades texturais, geoquímicas e mineralógicas destes solos dependem não só da composição química da rocha mãe, mas principalmente das características geomorfológicas e climatéricas locais. Na região em estudo, seleccionaram-se locais de amostragem, que se estendem desde a província do Kwanza-Norte (Kassenda, no Alto Dondo), passando pela província do Kwanza-Sul (Cangulo, Quibala e Waco Kungo), até ao Planalto do Huambo, onde se colheram amostras de rocha sã, rocha alterada e respectivo solo residual, ao longo de cada perfil de alteração. Realizaram-se análises de caracterização geoquímica por Fluorescência de Raios-X dos elementos maiores e menores, e de caracterização mineralógica por Difracção de Raios–X, tanto nas amostras de rocha sã, como no respectivo solo residual. Apresentam-se os resultados obtidos e a sua análise comparativa entre os diferentes locais de amostragem, assim como ao longo de cada perfil de alteração. Os resultados obtidos permitem contribuir para o conhecimento dos fenómenos de alteração geoquímica em zonas tropicais, como é o caso de Angola

Influence of geological features (geochemistry and mineralogy) of soil witch constitutes adobes in their durability - Huambo, Angola.

After long years of war, great efforts have been made for the socio-economic development of Angola, mainly in the construction industry. Among the construction techniques, the Adobe is the most used in the province of Huambo, especially by low-income families, which constitute the majority. This technique was established as a historical heritage in the culture of that population. The Huambo province is located in the central region of Angola (Central Plateau) and is bounded on the northeast and east by the province of Bié, on the south and southern by province of Huila, and on the west by the province of Benguela and on the northwest by the province of Kwanza Sul. Has an area of 35,771 km2 and approximately 2,301,524 inhabitants, which corresponds to 58 inhabitants per km2 (Government of the Province of Huambo, 2006). The buildings in this province, particularly in rural areas, were deeply marked by war. Given the current scenario of development of the country and considering the possibility of integrate systems and traditional building materials, that respect the environment and fit harmoniously into its natural habitat, one of the alternative options in the actual construction, undergoes resume old solutions and traditional materials such as adobe construction.It is in this context that this project is part of a scientific research in order to permit the improvement and optimization of these traditional solutions, responding to current demands for social, economic and environmental sustainability. The adobe is a building element with potential degradation by water. Due to the climate, subtropical, hot and humid, and geomorphology of the province, about 1000 to 2000 meters of altitude and an extensive river system, these buildings can be vulnerable and present early degradation, exacerbated by lack of knowledge of the properties of geomaterials used and techniques that allow their stabilization and conservation. This paper aims to study the influence of mineralogy and geochemistry of soils used in the production of adobes applied in the construction of habitations, mainly, because from this knowledge, we can develop alternatives to the resolution of recorded pathologies and to improve the strength and durability of those adobes. For this purpose, soil samples were collected, in which mineralogical and geochemical tests were performed. Simultaneously, durability and erodibility tests were done by the method of Geelong in the selected adobes. The results obtained from this research will identify, select and characterize the materials and methods used in construction in raw earth, contributing to the development of knowledge of these sustainable buildings solutions with a strong presence in the Huambo region. From the analysis of the data obtained will be defined a strategy for the next steps of the scientific research project in course designated "Earth Construction in Angola. Characterization, applications and potentialities.”. This project aims to encourage the use of the geomaterials in ecological construction and contribute, however modestly, in building solutions with better performance characteristics, comfort, safety, durability and sustainability

Combined EXAFS and ab initio study of copper complex geometries adsorbed on natural illite

The adsorption of copper on the 2:1 clay mineral illite (0.4 to 20 μm in size) was studied using a combination of extended X-ray adsorption fine structure (EXAFS) and hybrid-Density Functional Theory (DFT) modelling. The study evaluates the effect of varying pH and copper concentration on the mechanisms of copper adsorption in solutions at background electrolyte concentration typical of natural surface continental freshwaters in granitic environments. The EXAFS spectra revealed both the elongated square pyramidal and Jahn-Teller octahedral coordinated copper clusters as feasible with the former providing better fits using spertiniite (crystalline copper hydroxide) as model compound. Additionally, ab initio calculations also predicted the square pyramidal geometry to be more stable. Copper ions have four Oeq at an average distance of 1.95(1) Å and two independent Oax at average distances of 2.32(16) Å and 3.06(9) Å, with the latter decreasing to 2.97(2) Å as copper concentration and pH are increased. This may reveal different mechanism by which copper adsorbs on illite, as a weakly bound complex at low pH likely at exchange and edge sites and changing towards more strongly bound complexes at high affinity edge sites at higher pH and copper loads. Above 1% Cu model fits suggest formation of copper oligomers with average Cu-Cu distance of 3.10(2) Å. These occur at pH > 6, where the correlation between Cu-Cu and Al-Al distances in the illite edge surfaces supports the formation of surface precipitates

Problems of Analysis by FTIR of Calcium Sulphate-Based Preparatory Layers: The Case of a Group of 16th-Century Portuguese Paintings

This paper provides a contribution to FTIR analysis of calcium sulphate-based grounds of paintings when a mixture of compounds with different degrees of hydration is present. The study is based on the analysis with that technique, electron microscopy coupled with energy-dispersive X-ray spectrometry and X-ray diffraction of both the grounds of 16th-century Portuguese paintings and reference samples prepared with anhydrite and calcium sulphate dihydrate bound in an animal glue solution. It is shown that the interpretation of the degree of hydration of calcium sulphate ground samples using FTIR cannot be based solely on the study of the hydroxyl bands, as is usual in routine work, but that small deviations of the S–O vibration bands are an important indicator of the presence of anhydrite in the grounds.info:eu-repo/semantics/publishedVersio

MINERALOGICAL COMPARISON STUDY OF OLD MORTARS FROM SOUTHERN PORTUGAL CATHEDRALS (EVORA AND ELVAS) Characterization of Roman mortars from the historical town of Mértola in Heritage, Weathering and Conservation

Abstract The study of old mortars, based on integrated methodologies that combine mineralogical, microstructural, chemical, physical and mechanical characterization has an important role on the preservation of architectonical cultural heritage, allowing a deep knowledge about the materials used, construction techniques, possible repairs and behavior References [1] M.R. Veiga, J. Aguiar, A.S. Silva, F. Carvalho, Methodologies for characterisation and repair of mortars of ancient buildings i

A comparative mobile Raman study for the on field analysis of the Mosaico de los Amores of the Cástulo Archaeological Site (Linares, Spain)

An in situ archaeometrical campaign was organized in 2018 for the physicochemical analysis of the exceptional Mosaico de los Amores of the Cástulo archaeological site (Linares, Spain). Several mobile instruments were brought on the field to investigate the colourful tesserae of the mosaic. The main aim of the current research paper is the comparison of different mobile instruments and their applicability on measuring in open air environments. In this study, the comparison of four mobile Raman instruments, using different excitation lasers and technologies, is discussed. Three portable, the EZRaman‐I dual Raman analyser from TSI Inc. (USA), the i‐Raman® EX from BWTEK (USA), and the BWS445‐785S InnoRam™ Raman spectrometer from BWTEK (USA), and one handheld system, the Bravo Raman spectrometer from Bruker (Europe), are compared in terms of their characteristics, applicability, and performance when conducting non‐invasive and non‐destructive analysis