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See detailTalc schist deposits from central Cameroon: Mineralogical and physico-chemical characterization
Woguia, Damaris Laure ULiege; Fagel, Nathalie ULiege; Pirard, Eric ULiege et al

in Journal of African Earth Sciences (2021), 178

Talc schist deposits are reported in central Cameroon region, and different alteration zones were determined depending on differences related to the texture and color of the host rock. For the purpose of ... [more ▼]

Talc schist deposits are reported in central Cameroon region, and different alteration zones were determined depending on differences related to the texture and color of the host rock. For the purpose of determining mineralogical and physicochemical characteristics of talc schist, a total of 45 samples from the sites studied were collected and analyzed using an array of physico-chemical methods. Talc schist samples are mainly composed of variable amount of talc associated with plagioclase and clay minerals. Three groups of mineral association were determined: i) talc with small amount of chlorite and traces of kaolinite, ii) talc with high amount of chlorite, iii) variable amount of talc with plagioclase and clay minerals. The talc schist samples have homogeneous grain-sizes and are classified as silty sand or sandy silt. The occurrence of Ni and Cr in the talc schists are consistent with the composition of the talc deposits formed in relation to ultramafic rocks. The genesis of talc is due to hydrothermal fluid circulation in ultramafic rocks, attested by the occurrence of S and P. [less ▲]

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See detailGisements de talc schists du Centre Cameroun: Caractérisation minéralogique et physico-chimique
Woguia, Damaris Laure ULiege; Fagel, Nathalie ULiege; El Ouahabi, Meriam ULiege

Conference (2021, May)

Le talc est un silicate de magnésium hydraté (en feuillets) de formule Mg3 Si4 O10 (OH)2. Le talc est largement utilisé dans diverses applications industrielles en raison de ses propriétés physico ... [more ▼]

Le talc est un silicate de magnésium hydraté (en feuillets) de formule Mg3 Si4 O10 (OH)2. Le talc est largement utilisé dans diverses applications industrielles en raison de ses propriétés physico-chimiques particulières, telles qu'une stabilité thermique élevée, une faible conductivité électrique, de bonnes propriétés d'absorption et de désorption, une large distribution granulométrique et une grande surface spécifique (Nkoumbou et al., 2007; Dumas et al., 2013; Ersoy et al., 2013). La composition chimique du talc est principalement liée à la nature du protolithe et aux conditions physico-chimiques qui ont précédé sa formation. Des dépôts de talc schists sont signalés dans la région centrale du Cameroun(Fig.1), et différentes zones d'altération ont été déterminées en fonction des différences liées à la texture et à la couleur de la roche mère. Afin de déterminer les caractéristiques minéralogiques et physico-chimiques du talc schist, 45 échantillons ont été préleves dans plusieurs sites. Les échantillons de talc schists sont principalement composés d'une quantité variable de talc associée au plagioclase et aux minéraux argileux. Trois groupes d'association minérale ont été déterminés: i) talc avec une petite quantité de chlorite et des traces de kaolinite, ii) talc avec une grande quantité de chlorite, iii) quantité variable de talc avec plagioclase et minéraux argileux. Les échantillons de talc schists ont des granulométries homogènes et sont classés comme sable limoneux ou limon sableux. Les spectres XRD des fractions d'argile (<2 µm) montrent la présence de talc, de kaolinite, de chlorite et de vermiculite (Fig. 2). Le talc apparaît à d = 9,31 Â qui reste inchangé après la solvatation de l'éthylène glycol et le chauffage à 500 ° C. Le chlorite présente des pics caractéristiques à d = 14,24 Å et d = 7,14 Å, ce dernier pic est également dû à l'apport de kaolinite. Les spectres XRD révèlent principalement du chlorite altéré (Fig. 4). La chlorite détritique montre une variation des réflexions basales dans différents échantillons indiquant la teneur différente en Fe du chlorite. La présence de Ni et Cr dans les schistes de talc est cohérente avec la composition des dépôts de talc formés par rapport aux roches ultramafiques. La genèse du talc est due à la circulation des fluides hydrothermaux dans les roches ultramafiques, attestée par la présence de S et P. [less ▲]

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See detailCandlestick stalagmite’s eigenfrequency characterisation with ambient seismic noise and 3D scan, a step to support seismic hazard assessment
Martin, Aurélie ULiege; Lecocq, Thomas; Hinzen, Klaus-G. et al

in EGU General Assembly Conference Abstracts (2021, April)

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See detailLate Holocene Paleonvironmental Evolution of Two Coastal Lakes in Mediterranean Chile and Its Implications for Conservation Planning
Montes, Isis-Yelena; Banegas-Medina, Andy; Fagel, Nathalie ULiege et al

in Applied Sciences (2021), 11(8),

Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are still relatively scarce. Anthropogenic impacts have evidenced trophic state changes and an increase in ... [more ▼]

Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are still relatively scarce. Anthropogenic impacts have evidenced trophic state changes and an increase in cyanobacterial blooms in the lacustrine system of San Pedro de la Paz in the last decades. Here, we reconstructed primary production and sedimentological changes spanning the past 2500 years in two coastal lakes in Mediterranean Chile. A multiproxy approach including sedimentological, biogenic silica, carbon and nitrogen isotopes and fossil pigments analysis in sediment cores was performed in Laguna Grande (LGSP) and Laguna Chica de San Pedro (LCSP). A marked change in the sedimentology of the lakes, likely related to the terrigenous sediment inputs derived by a transition from an arid condition in the mid-Holocene to a more humid condition in the late Holocene that favoured arboreal forest establishment at 100 BC–AD 150. A period of low primary production was identified between 850 to 1050 AC for LCSP, suggesting moist and cold conditions that were possibly related to La Niña events. In recent decades, there have been increases in primary production, probably resulting from anthropogenic disturbances. These likely include the clearance of native vegetation, the introduction of exotic tree species, and urbanisation, which in turn, resulted in nutrient inputs and hence eutrophication. We conclude that an integrated management program for both lakes is urgently needed. [less ▲]

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See detailPhosphogypsum and Black Steel Slag as Additives for Ecological Bentonite-Based Materials: Microstructure and Characterization
Harrou, Achraf; Gharibi, Elkhadir; Taha, Yassine et al

in Minerals (2020)

The Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they ... [more ▼]

The Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they were incorporated into bentonite (B) mixed with lime (L). The studied mixtures (BLW, BL–PG–W and BL–PG–Ss–W) were analyzed by X-ray diffraction, Infrared spectroscopy, Raman spectroscopy and SEM/EDX analysis. Compressive strength tests were performed on hardened specimens. The results obtained show that the hydration kinetics of the B–L–W and B–L–PG–W mixtures are slow. The addition of PG to a bentonite––lime mixture induces the formation of new microstructures such as hydrated calcium silicate (C–S–H) and ettringite, which increases the compressive strength of the cementitious specimens. The addition of the Ss to a mixture composed of 8%PG and 8%L–B accelerates the kinetics of hydration and activates the pozzolanic reaction. The presence of C2S in the slag helps to increase the mechanical strength of the mixture B–L–PG–Ss. The compressive strength of the mixtures BL–W, BL–PG–W and BL–PG–Ss–W increases from 15 to 28 days of setting. After 28 days of setting, 8% of Sc added to the mixture 8% PG–8%L–B is responsible for an increase of the compressive strength to 0.6 MPa. [less ▲]

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See detailComment on: “A novel approach to peatlands as archives of total cumulative spatial pollution loads from atmospheric deposition of airborne elements complementary to EMEP data: Priority pollutants (Pb, Cd, Hg)” by Ewa Miszczak, Sebastian Stefaniak, Adam Michczyński, Eiliv Steinnes and Irena Twardowska
De Vleeschouwer, F.; Baron, S.; Cloy, J.M. et al

in Science of the Total Environment (2020), 737(1),

A recent paper by Miszczak et al. (2020) examines metal contamination of mires in Poland and Norway. The authors conclude that lead (Pb) records in ombrotrophic peatlands cannot be used to reconstruct the ... [more ▼]

A recent paper by Miszczak et al. (2020) examines metal contamination of mires in Poland and Norway. The authors conclude that lead (Pb) records in ombrotrophic peatlands cannot be used to reconstruct the chronological history of anthropogenic activities due to post-depositional mobility of the metal. We contest this general conclusion which stands in contrast with a significant body of literature demonstrating that Pb is largely immobile in the vast majority of ombrotrophic peatlands. Our aim is to reaffirm the crucial contribution that peat records have made to our knowledge of atmospheric Pb contamination. In addition, we reiterate the necessity of following established protocols to produce reliable records of anthropogenic Pb contamination in environmental archives. [less ▲]

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See detailPhysico-mechanical properties of phosphogypsum and black steel slag as aggregate for bentonite-lime based materials
Harrou, Achraf; Gharibi, Elkhadir; Nasri, Hicham et al

in Materials Today: Proceedings (2020)

This study aim to valorizing phosphogypsum (PG) and steel slag (Sc) in geotechnical applications by incorporating them in bentonite (B) stabilized by lime (L). Mineralogical (XRD), spectroscopic (IR-FTIR ... [more ▼]

This study aim to valorizing phosphogypsum (PG) and steel slag (Sc) in geotechnical applications by incorporating them in bentonite (B) stabilized by lime (L). Mineralogical (XRD), spectroscopic (IR-FTIR), geotechnical (Atterberg limits) analyzes were carried out on the raw material. Resistance to axial compression (UCS) was performed on cylindrical specimens prepared for mixtures B-L, B-L-PG, B-L-PG-Sc and cured for 3, 7, 15 and 28 days. The results obtained revealed that the mechanical strength increases with the addition of PG, and reaches its maximum value for a water content equal to 46%. Slag improves the strength of the B-L-PG mixture. The pH and the electrical conductivity of the solutions containing in porosity of the various mixtures decrease over time. The observed decrease is greatest for B-L-PG and B-L-PG-Sc mixtures due to pozzolanic reactions. [less ▲]

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See detailNon-destructive portable X-ray Fluorescence (pXRF) method for the characterization of Islamic architectural ceramic: Example of Saadian tombs and El Badi palace ceramics (Marrakech, Morocco)
El Halim, Mouhssin ULiege; Daoudi, Lahcen; EL Alaoui, El Fels et al

in Journal of Archaeological Science: Reports (2020), 32

Archeological decorated ceramics from the Saadian tombs and El Badi palace sites (Marrakech, Morocco) have reached an advanced deterioration phase; the glazes have been increasingly weakened due to human ... [more ▼]

Archeological decorated ceramics from the Saadian tombs and El Badi palace sites (Marrakech, Morocco) have reached an advanced deterioration phase; the glazes have been increasingly weakened due to human and environmental impacts over time. Portable X-ray Fluorescence (pXRF) was performed in situ and on samples selected from these two monuments, in order to define the chemical agents responsible for the color of the studied glazed ceramics and to determine their evolution over time to help find answers and link between degradations and chemical compositions of different type of glazes. The results show that all samples are lead-silica type glazes with 25–59 wt% of PbO and 51 wt% of SiO2. The coloring agents used for the original glaze are conventional, copper (Cu2+) for the green color, iron (Fe3+) and manganese (Mn2+) for the yellow and black glaze. Phosphorus (P2O5), comes from carbonate mineral phases, is responsible for the blue opalescence of glazes. The study reveals that the ceramic industry has evolved recently in Morocco; elements such as calcium and potassium are currently used in small quantities while lead is increasingly used as flux in the glaze mixture. Iron and copper are still used for black, yellow and green colors, while the use of phosphorus has been replaced by other elements such as cobalt and copper. [less ▲]

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See detailPhysico-chemical and mineralogical characterization of clay materials suitable for production of stabilized compressed earth blocks
Nshimiyimana, Philbert ULiege; Fagel, Nathalie ULiege; Messan, Adamah et al

in Construction and Building Materials (2020), 241

The main objective of this study is to characterize the physico-chemical and mineral properties of clay materials from Burkina Faso to produce stabilized compressed earth blocks (CEBs). The reactivity of ... [more ▼]

The main objective of this study is to characterize the physico-chemical and mineral properties of clay materials from Burkina Faso to produce stabilized compressed earth blocks (CEBs). The reactivity of the clay materials was tested based on the electrical conductivity of solutions and the compressive strength of CEBs stabilized with 0–20 wt% CCR (calcium carbide residue) and cured for 45 days at 40 ± 2 °C. Pabre and Kossodo respectively contain the highest fractions of clay (20–30%) and gravel (40%). Saaba and Pabre contain the highest content of kaolinite (60–70%) and quartz (45–60%) and recorded the highest and lowest reactivity, respectively. The compressive strength of CEBs stabilized with 20% CCR improved tenfold (0.8–8.3 MPa) for Saaba and only 2.6 (2–7.1 MPa) for Pabre. The clay materials in the present study are suitable to produce CCR-stabilized CEBs for load-bearing construction. [less ▲]

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See detailWhite pottery production in the Middle Meuse valley: sustainability of clay resources during the early Middle Ages
Van Wersch, Line ULiege; de Longueville, Sylvie; Dussubieux, Laure et al

in Archaeological and Anthropological Sciences (2020), (2020) 12:150

This study of white pottery from the Merovingian and Carolingian periods traces the use of white clay resources in the Middle Meuse valley at the beginning of the Middle Ages. The petrographic study of 56 ... [more ▼]

This study of white pottery from the Merovingian and Carolingian periods traces the use of white clay resources in the Middle Meuse valley at the beginning of the Middle Ages. The petrographic study of 56 sherds, the chemical analysis of 40 samples, and XRD study of 12 of them coming from 4 sites reach the changes of the process between the two time periods, characterize the production of three Carolingian workshops, and consider the material supply in the mechanism of potters’ settlement. It appears that, between the Antiquity and the Modern period, the white kaolinitic material has always been exploited. The main technical changes between the Merovingian and the Carolingian periods are related to the specific selection of these clays that allow to produce white pottery and cooking wares with few inclusions. The Carolingian workshops used the material available in their environment that can be differentiated by chemistry and mineralogy. Finally, it appears that the selection of this particular type of clay also oriented the choice of the place where the potters settled or at least the longevity of some of the workshops. [less ▲]

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See detailCharacterizing Stalagmites’ Eigenfrequencies by Combining In Situ Vibration Measurements and Finite Element Modeling Based on 3D Scans
Martin, Aurélie ULiege; lecocq, Thomas; Hinzen, Klaus-G. et al

in Geosciences (2020), 10(10),

Broken or deformed speleothems have been used as indicators of paleo-earthquakes since the 1990s; however, a causal link is difficult to prove except for some thin speleothems. In contrast, the presence ... [more ▼]

Broken or deformed speleothems have been used as indicators of paleo-earthquakes since the 1990s; however, a causal link is difficult to prove except for some thin speleothems. In contrast, the presence of intact speleothems permits estimating an upper limit of the level of horizontal ground motions of past seismicity in the area. The natural frequencies of speleothems are fundamental parameters for their response to earthquakes. This study proposes a new method of in situ characterization of these natural frequencies. Tested in the Han-sur-Lesse cave (Belgian Ardennes), the method is based on recording the ambient seismic noise using three-component sensors on a stalagmite and a 3D laser scan of its shape. The ambient seismic noise records allow a precise determination of the eigenfrequencies of the stalagmite. In addition, numerical models based on the 3D scan show good consistency between measured and modeled data. The joint analysis of these two techniques concludes that the shape of the stalagmite (elliptical cross-section and shape irregularities) influence the eigenfrequencies and polarization of the modes while also causing a near-orthogonal split of natural frequencies. The motions recorded on the stalagmite show significant amplification compared to those recorded at the free surface outside the cave, which has a strong impact on seismic hazard assessment based on speleothems. [less ▲]

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See detailProvenance of northwestern Patagonian river sediments (44–48°S): A critical evaluation of mineralogical, geochemical and isotopic tracers.
Liu, Dai; Bertrand, S.; Villaseñor, T. et al

in Sedimentary Geology (2020), (105744),

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See detailImprovement of lifetime of compressed earth blocks by adding limestone, sandstone and porphyry aggregates
Mango-Itulamya, Lavie Arsène ULiege; Collin, Frédéric ULiege; Fagel, Nathalie ULiege

in Journal of Building Engineering (2020), 29

This article studies the performance improvement of four properties, i.e. drying shrinkage, compressive strength, water absorption and abrasion resistance of Compressed Earth Blocks (CEB) by the addition ... [more ▼]

This article studies the performance improvement of four properties, i.e. drying shrinkage, compressive strength, water absorption and abrasion resistance of Compressed Earth Blocks (CEB) by the addition of 3 different types of aggregates (limestone, sandstone and porphyry). Five soils selected from Belgian active quarries were used. For each soil, the fabrication of CEB was done according to 5 formulations including 0%, 20%, 33%, 43% and 50% of aggregate addition (by volume). The addition of any aggregate decreases the drying shrinkage and water absorption of CEB. The different lithology of each aggregate did not influence the results. © 2019 [less ▲]

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See detailSwelling properties and lime stabilization of N'Gaous expansive marls, NE Algeria
Benyahia, S.; Boumezbeur, A.; Lamouri, B. et al

in Journal of African Earth Sciences (2020)

The interaction of marly soils and buildings in the town of N'Gaous has led to the appearance of deformations and disturbances that have affected many constructions due to the swelling of the underlying ... [more ▼]

The interaction of marly soils and buildings in the town of N'Gaous has led to the appearance of deformations and disturbances that have affected many constructions due to the swelling of the underlying soil. In addition, when these soils are used as construction material, embankments, they are extremely problematic. In this article, three sets of samples, from three different locations, were sampled. Their average carbonate content varies from 14% to 33%.The mineralogical and microsctructural characteristics of these soils are studied by X-ray diffraction (XRD), TG/DTA and SEM analysis. These are mainly smectite clays containing kaolinite and other minor constituents. They all have similar structure, laminar texture with an arrangement of clay particles oriented parallel to the bedding and pores of varying size. These soils are very plastic and have a plasticity index ranging from 41.5 to 54.3%. It was found that the swelling pressure before any treatment ranged from 2.3 to 2.7 bars, after treatment the swelling pressure becomes stable with 5% lime, this behavior has a link with the formation of a cementitious phase of calcium silicate hydrate (CSH) type, as revealed by XRD, ATD/TG and analysis and SEM. In terms of results, it was found that the addition of quicklime has clearly reduced the swelling of the tested samples. It was also found that the presence of carbonates with the above mentioned contents in the studied samples (<50%) does not affect negatively the lime treatment of these soils. However, it promotes the stabilization of swelling, which gives encouraging results. [less ▲]

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See detailNew application of GIS and statistical analysis in mapping the distribution of quaternary calcrete (Tensift Al Haouz area, Central Morocco)
Elidrissi, S.; Omdi, S.; El Azhari, F.E. et al

in Catena (2020), 188

Quaternary calcretes are widespread in soils of many regions of the world especially in semi arid and arid areas. Their development has been studied worldwide for more than a century involving various ... [more ▼]

Quaternary calcretes are widespread in soils of many regions of the world especially in semi arid and arid areas. Their development has been studied worldwide for more than a century involving various disciplines and resulting in large amounts of data concerning their evolution. In this article, the geographical distribution of calcrete has been studied by combining Geographical Information Systems (GIS) and statistical analysis. In this paper, we present a qualitative approach that incorporates topographic, geological, hydrogeological and climatic data as well as field observations. After getting all four parameters, they were divided into classes and an index value has been assigned to each of them according to influence degree on calcrete development. Finally, all the parameters are superimposed to prepare the final map of calcrete distribution. The multivariate statistical analysis techniques used were principal component analysis and cluster analysis. Both methods were performed to discuss the potential relations among the investigated parametres (CaCO3 (%), Palygorskite (%), slope (%)) and calcrete evolution. The qualitative approach adopted provided a distribution map predicting the possible areas where different calcrete forms might occur and allowed to elucidate the degree of influence of environmental factors on the evolution of calcrete. The accuracy of this method has been estimated by comparing it with 52 cross-section data from the field. This approach proved to be successful in this study. The results of statistical analysis confirm the results obtained using GIS method and highlight the influence of the studied environmental factors on the spatial distribution of different types of calcrete. [less ▲]

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See detailUse of bathymetry and clay mineralogy of reservoir sediment to reconstruct the recent changes in sediment yields from a mountain catchment in the Western High Atlas region, Morocco
Gourfi, A.; Daoudi, L.; Rhoujjati, L. et al

in Catena (2020)

The dam of Takerkoust, located at the outlet side of N'fis Basin (Western High Atlas of Morocco), is one of the strategic reservoirs in Morocco facing a serious problem of siltation due to soil erosion. A ... [more ▼]

The dam of Takerkoust, located at the outlet side of N'fis Basin (Western High Atlas of Morocco), is one of the strategic reservoirs in Morocco facing a serious problem of siltation due to soil erosion. A paleo-hydrology approach combining chronological and sedimentological analyses is conducted to understand the evolution of the depositional sediment history of the Takerkoust reservoir between 1988 and 2016. First, a series of 8 bathymetric surveys in the Takerkoust reservoir was used to determine the chronology of flood event deposits. Second, grain size distribution, clay mineralogy (XRD) and organic matter content were analyzed in 2 cores drilled in the Takerkoust reservoir and the newly build Ouirgane reservoir in upstream (from which 46 samples were taken). Third, Soils samples collected from the uppermost soil horizons (First 5 cm) of different localities of the N'fis watershed were also analyzed to identify sediments origins. Eleven couplets with different textures and thickness are identified in the Takerkoust reservoir corresponding to the period 1988–2016. The highest correlation is observed between instantaneous maximum flow and thickness of the sandy component of the couplets. The variation of the siltation rate allows highlighting two distinct periods: the oldest period (1988–1999) characterized by a high sediment yield SY (908.6 t·km−2·yr−1) and a youngest one (1999–2016) characterized by a low SY (203.9 t·km−2·yr−1). The newly built Ouirgane dam, seems to be responsible for the decreasing siltation rate and change of the clay assemblages of the sedimentary series in Takerkoust reservoir. [less ▲]

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See detailCharacterization and origin of two Fe-rich bentonites from Westerwald (Germany)
Fontaine, François ULiege; Christidis, George; Yans, Johan et al

in Applied Clay Science (2020), 187

The Westerwald region is one of the major ceramic clay mining areas of Germany. The mined clays were deposited on the weathered Rhenish massif during Eocene and Oligocene and were protected from erosion ... [more ▼]

The Westerwald region is one of the major ceramic clay mining areas of Germany. The mined clays were deposited on the weathered Rhenish massif during Eocene and Oligocene and were protected from erosion by a large alkaline basalt cover. Two Fe-rich bentonite layers exposed in quarries of the Eastern part of the Westerwald were investigated with X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, optical microscopy, scanning electron microscopy, chemical analyses and cation exchange capacity (CEC). In both bentonite layers, the main mineral is a high-charge Fe-rich beidellite containing exchangeable Ca and Mg. Even if they both derive from mafic volcanic rocks, the difference in accessory minerals and trace element content leads to the conclusion that they have a different precursor. The lower bentonite layer also contains talc, saponite, halloysite, goethite and anatase. It is part of the Palaeozoic bedrock and results from the weathering of a Lower Carboniferous metabasalt. The upper bentonite layer has Upper Oligocene age and has been derived from the alteration of tuffite with a composition ranging from alkali basalt to trachyte. This bentonite is linked to the first eruptions of the intraplate Cenozoic volcanic activity of the Westerwald. [less ▲]

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See detailPhosphogypsum waste as additives to lime stabilization of bentonite
Oumnih, Safae ULiege; Bekkouch, Nadia ULiege; Gharibi, El Khadir et al

in Sustainable Environment Research (2019)

Waste recycling with increasing the lifecycle of resource is a novel approach for enhancing circular economy. Within this context, this study aims to give a second life cycle to phosphogypsum (PG) waste ... [more ▼]

Waste recycling with increasing the lifecycle of resource is a novel approach for enhancing circular economy. Within this context, this study aims to give a second life cycle to phosphogypsum (PG) waste, which is a by-product from phosphoric acid manufacture, as useful resources. This study evaluates the sustainability of this harmful waste, which is accumulated in large stockpiles and becomes hazardous during storage, and to stabilize bentonite-based concrete intended for road construction. The effect of raw bentonite (Ca-Na montmorillonite), PG, and lime on the properties of cementitious materials has been investigated through various tests. The properties examined include chemistry (X-ray Fluorescence Spectrometry), mineralogy (X-ray Powder Diffraction and Fourier-Transform Infrared Spectroscopy), calorimetry (Differential Thermal Analysis/Thermogravimetry) and microstructure (Scanning Electron Microscopy) of the mortar based on different mixtures of bentonite, PG and lime. The result show that lime and PG addition involves in the formation of new nanocrystalline phases and the disappearance of certain minerals as portlandite. Calcium silicate hydrate gel appeared in the mixture with 8% of lime, whereas strätlingite was neoformed in the mixture with 8% of lime and 8% of PG. These nanocrystalline phases are responsible for enhancing mechanical strength through the pozzoloanic reaction. [less ▲]

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See detailMechanical properties and durability of lime mortar using aggregate made from phosphogypsum and steel mill slag
Harrou, Achraf; Oumnih, Safae ULiege; Gharibi, Elkhadir et al

Poster (2019, April)

The present investigation deals with the utilization of phosphogypsum and steel mill slag combined with lime and raw bentonite as a cementitious material used for road construction and durability of ... [more ▼]

The present investigation deals with the utilization of phosphogypsum and steel mill slag combined with lime and raw bentonite as a cementitious material used for road construction and durability of mortar. The result reveals that the stabilization of bentonite by lime enhances mechanical strength of the material, mainly due to the alkaline environment promoting the formation of aluminates and silicates found in Portland cement. Additionally, the addition of phosphogypsum increases the compressive strength by 7 times, with an increase of 20% compared to lime-bentonite aggregate. This is partially due to stratlingite formation, obtained by reaction of CAH10 with C-S-H. The steel mill slag further increases this compressive strength by 10 times, because the occurrence of dicalcium silicate and metal flakes. [less ▲]

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See detailMoroccan clay deposits: Physico-chemical properties in view of provenance studies on ancient ceramics
El Ouahabi, Meriam ULiege; El Boudour El Idrissi, Hicham ULiege; Daoudi, Lahcen et al

in Applied Clay Science (2019), 172(65-74),

Features of clayey raw materials from most important traditional pottery centers in the vicinity of the main medieval sites in Morocco, and their fired products were investigated. Besides clay from the ... [more ▼]

Features of clayey raw materials from most important traditional pottery centers in the vicinity of the main medieval sites in Morocco, and their fired products were investigated. Besides clay from the North of Morocco, the used raw material was illitic clays (10–100%) and smectite-rich clays (0–67%) with variable amount of kaolinite, quartz and feldspars. Chlorite was also present in a small amount. The main major oxides were Si2O, Al2O3 and CaO. The fired tests (800–1100 °C) displayed a decrease in open porosity of the sintered clay by raising the temperature, mainly from 1000 °C due to the inception of melting. This change was coupled with the change in mineralogical composition. New crystalline phases as Ca silicates (diopside and gehlenite), hematite, spinel and mullite occurred during firing process, attesting to the inception of melting and were responsible for porosity reduction. Reference clays for pottery were established based on the clay mineralogy and chemical composition. The present study would help to answer some archeological questions concerning possible sourcing areas for archeological ceramics, to determine techniques for the production of artefacts, and then to interpret cultural influences. Furthermore, the obtained results will support the inception of development of a compositional database for Moroccan pottery. [less ▲]

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