References of "Fagel, Nathalie"
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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 Idrissia,, Hicham; 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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See detailEconomic resilience of Carthage during the Punic Wars: Insights from sediments of the Medjerda delta around Utica (Tunisia).
Delile, H.; Pleuger, Elisa ULiege; Blichert-Toft, J. et al

in Proceedings of the National Academy of Sciences of the United States of America (2019), 116(20), 9764-9769

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See detailExploration of the maritime façade of Utica: the potential location of the Phoenician and Roman harbours
Pleuger, Elisa ULiege; Goiran, J.-Ph; Delile, H. et al

in Quaternary International (2019)

According to ancient literary tradition, Utica is considered to be one of the first three Phoenician foundations in the Western Mediterranean, supposedly founded in 1101 BC by Levantines from Tyre. In the ... [more ▼]

According to ancient literary tradition, Utica is considered to be one of the first three Phoenician foundations in the Western Mediterranean, supposedly founded in 1101 BC by Levantines from Tyre. In the Phoenician and Roman periods, it was an important merchant coastal town, on a promontory facing the sea. Over the centuries Utica lost its access to the sea, and its ports silted up as a consequence of the activity of the wadi Medjerda, which flowed to the south of the city. Despite over a century of investigation by archaeologists and associated researchers, the location of the city’s harbour structures from the Phoenician and Roman periods remains unknown, buried under sediments resulting from the progradation of the Medjerda. Based on the study of sedimentary cores, the research presented here highlights the existence of a long maritime façade to the north of the Utica promontory in Phoenician and Roman times. A deep-water marine environment is attested in the former bay from the 6th mill. BC and the depth of the water column along the northern façade was still 2 m around the 4th – 3rd c. BC. Another core to the east of the Kalaat El Andalous promontory showed the possibilitythat this sector was a sheltered harbour during the Phoenician and Roman periods. This paper illustrates the contribution of geoarchaeology to address this archaeological problem and to understand the relations of this important port city with the sea. [less ▲]

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See detailMineralogical Transformation and Microstructure of the alluvial clays firing
Bomeni, I.Y.; Wouatong, A.S.L.; Ngapgue, F. et al

in Science of Sintering (2019), 51

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See detailValorisation of soils from Kinshasa and Kongo Central regions (Democratic Republic of Congo) for raw earth bricks
Mango-Itulamya, Lavie Arsène ULiege; Pilate, Palcal; Collin, Frédéric ULiege et al

Conference (2018, December 07)

Soil is a building material widely used in Kinshasa and Kongo Central regions. Its exploitation is generally artisanal. Soils extracted are largely used for the manufacture of wood-fired bricks, with ... [more ▼]

Soil is a building material widely used in Kinshasa and Kongo Central regions. Its exploitation is generally artisanal. Soils extracted are largely used for the manufacture of wood-fired bricks, with consequent deforestation problems (Mango-Itulamya, 2015). In order to limit the production energy cost and to produce a sustainable building material, the use of raw earth bricks seems to be a solution. Six areas containing important soil deposits have been selected: Kinshasa, Mbanza Ngungu, Kasangulu, Nkamba, Kwilu Ngongo, and Lukala. Soils of these 6 zones were sampled and used to make raw earth bricks. [less ▲]

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See detailPosphogypsum waste valorization by acid attack with the presence of metallic iron
Oumnih, Safae ULiege; Bekkouch, Nadia ULiege; El Ouahabi, Meriam ULiege et al

Poster (2018, November 21)

During the classical production of phosphoric acid using phosphate rock, a high quantity of phosphogypsum “PG” waste is produced. Storage and management of this quantity present a serious problem, because ... [more ▼]

During the classical production of phosphoric acid using phosphate rock, a high quantity of phosphogypsum “PG” waste is produced. Storage and management of this quantity present a serious problem, because the elevated levels of impurities which originate primarily from the source phosphate rock. The consumption or the re-use of this waste generates several environmental risks due to its composition. Several valorization processes of the PG, economic and environmental, are in phase of development and study. Among the valorization processes, we can find desulphurization, bacteriological or thermal methods, allowing to produce sulphur dioxide SO2 used in the synthesis of the sulphuric acid. The main objective of the present study is to develop an alternative technique to valorize the PG and produce sulphur dioxide “SO2”, using an alternative procedure based on a strong acid attack with the presence of a metal catalyst. The results indicate that the leaching of the PG with acid alone does not allow reduction of the sulfates ions dissolved in SO2. However, when the leaching occurs with the presence of the metal elements, the release of SO2 is observed. The values of the calculated ΔGr and ΔHr permit to discuss the possibility of the reactions involved and to argument the experimental results found. [less ▲]

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See detailStabilization of bentonite by treatment of lime and phosphogypsum
Bekkouch, Nadia ULiege; Oumnih, Safae ULiege; Fagel, Nathalie ULiege et al

Conference (2018, November)

Morocco produces 15 million tons of phosphogypsum residues coming mainly from the phosphate processing industry. Those acid wastes are rich in heavy metals. The release of heavy metals into the ... [more ▼]

Morocco produces 15 million tons of phosphogypsum residues coming mainly from the phosphate processing industry. Those acid wastes are rich in heavy metals. The release of heavy metals into the environment, and especially in seawater, results in a number of environmental problems. The present study aims at valorizing the phosphogypsum residues for geotechnical applications (e.g, roadbase, subbase, embankment material). In order to stabilize bentonite, we mixed it with different proportions of lime and phosphogypsum . The bentonites was sampled from a TRIBIA’s deposit located 15 km west of the city Nador in Northeast of Morocco,. For that purpose chemical (XRF), mineralogical (XRD), thermal (TAG), geotechnical (Atterberg limits) and mechanical (Proctor and compressive strength) analyzes were performed on the different mixtures of bentonite, phosphogypsum and lime. We observe that lime and phosphogypsum significantly enhance the behavior of bentonite through different reactions. First, a decrease in the plasticity index (PI) and density of the proctor optimum associated with an increase in the optimum water content can be observed. The texture of mixture evolves from a plastic state to a solid, friable, non-tacky state with a partial loss of sensitivity to water. Long-term modifications also occur. Indeed the lime raises the pH of the bentonite and causes an hydrolysis, It forms then crystalline aluminates and hydrated calcium silicates, acting as a binder between the grains thus causing an increase in the compressive strength. In contrast, the phosphogypsum decreases the time of setting [less ▲]

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See detailAnalytical study of ancient ceramics from the archaeological site of Aghmat, southern Morocco
El Halim, Mouhssin ULiege; Daoudi, Lahcen; El Ouahabi, Meriam ULiege et al

in Materiocedia: Proceedings Series on Materials (2018), 1(1), 47-58

This paper explores Aghmat archaeological materials (VII centuries) using two types of ceramics, come from a recent archaeological excavation in Aghmat (Morocco) in order to enhance documentation ... [more ▼]

This paper explores Aghmat archaeological materials (VII centuries) using two types of ceramics, come from a recent archaeological excavation in Aghmat (Morocco) in order to enhance documentation, conservation and restoration issues, then putting into value the architectural heritage. Fortuitously discovered in 2005, Aghmat village has allowed the reformulation of several hypotheses about Aghmat population skills in construction and handicrafts. Even though the areal extent of this archaeological site exceeds 20 Km2, no traces of furnaces have been found yet, only ruins of buildings and streets. Bricks and pottery samples were the most abundant types of ceramics founded. Mineralogical and chemical analyses of this materials provided information about the origin of raw materials and manufacturing process. The chemical compositions indicated that SiO2, Al2O3 and Fe2O3 are major elements while K2O and MgO are less abundant. The ceramics were produced using at least two raw materials, non calcareous clay of permo-triassic age for bricks, and carbonate quaternary clays for pottery samples, as the calcium oxide content is generally more than 10%. [less ▲]

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See detailBelgian clay geo-resources and their use for making compressed earth bricks
Mango-Itulamya, Lavie Arsène ULiege; Collin, Frédéric ULiege; Fagel, Nathalie ULiege

Conference (2018, September 14)

This study has two objectives: contribute to the knowledge of Belgian clays and evaluate their use for manufacture of compressed earth block (CEBs). Nineteen Belgian clays formations were sampled in 56 ... [more ▼]

This study has two objectives: contribute to the knowledge of Belgian clays and evaluate their use for manufacture of compressed earth block (CEBs). Nineteen Belgian clays formations were sampled in 56 sites and 135 samples were collected and analyzed. The analyzes focused on the determination of particle size, plasticity, nature and mineralogy, the main characteristics for assessing the suitability of the soil to make CEBs. These analyzes allow to classify the sampled formations in three categories: clays that can be used unchanged to make CEBs (2 formulations), clays that are suitable for the manufacture of CEBs but require modification (13 formulations) and clays that are unsuitable to the manufacture of CEBs (4 formulations). [less ▲]

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See detailGeotechnical and chemical properties of stabilized bentonite with lime-phosphogypsum
Oumnih, Safae ULiege; Bekkouch, Nadia ULiege; El Ouahabi, Meriam ULiege et al

Scientific conference (2018, September)

Phosphogypsum (PG), produced from phosphoric acid production, is accumulated in large stockpiles and occupies vast areas of land. The phosphate industry in Morocco produces 15 million tons of ... [more ▼]

Phosphogypsum (PG), produced from phosphoric acid production, is accumulated in large stockpiles and occupies vast areas of land. The phosphate industry in Morocco produces 15 million tons of phosphogypsum waste by year (Hakkou, 2016). Those wastes contain toxic elements which may cause environmental damage during storage, especially by contact with aquatic environments (Gaudry, 2007). The aim of this study was to propose a sustainable management of those harmful wastes. We test different mixings to trap the toxic elements. We mix some phosphogypsum waste with raw bentonite (B). Bentonite is abundant clay material in Morocco and is successfully used for decades as an adsorbent for removing toxic heavy metals from aqueous solutions (Chiban, 2012). The raw bentonite was sampled from the Tribia deposit located in Northeast of Morocco. We also test several mixings with both bentonite and lime (L). Chemical (XRF), mineralogical (XRD), thermal (ATG), geotechnical (Atterberg limits) and mechanical (Proctor and compressive strength) analyzes analysis were performed on the different mixtures. The results display that lime and phosphogypsum significantly enhance the behavior of bentonite by increasing the compressive strength through different reactions. The optimal results are reached when 8% of PG is added to the bentonite, highlighted by an increase of 20% compared to the mixture made only by bentonite and lime at 28 days (Fig. 1). Over time, long-term modifications occur. In particular, lime as a strong base raises the pH of the clay and causes silica and alumina mobilization. Phosphogypsum decreases the time of setting. It forms then aluminates and hydrated calcium silicates which, by crystallizing, act as a binder between the grains thus causing an increase in the compressive strength. In addition, immediate changes in geotechnical properties of bentonite were observed. Those changes are expressed by a decrease in the density of the Proctor optimum values and increase in the optimum water content with the addition of 5%, 8%, 10% and 15% of lime (Fig. 3). We suggest that the additional water is retained in the agglomerates resulting during the reaction of the lime with bentonite. The mixture evolves almost instantaneously from a plastic state to a solid, friable, non-tacky state and partially loses its sensitivity to water. The increase in unconfined compressive strength was the highest with 8% lime and 8% phosphogypsum (Fig. 2). Furthermore, the addition of phosphogypsum increases the liquid limit compared to the bentonite and lime mixture. [less ▲]

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See detailHigh-temperature XRD investigations of phase transformation in mineralogy: examples for clay used in ceramics and phosphate minerals
Fontaine, François ULiege; Hatert, Frédéric ULiege; Fagel, Nathalie ULiege

Poster (2018, September)

High-temperature X-ray diffraction is a technique used to determine the mineralogy of a sample at various, non-ambient, temperatures. It allows the measurement and visualisation of dehydration and ... [more ▼]

High-temperature X-ray diffraction is a technique used to determine the mineralogy of a sample at various, non-ambient, temperatures. It allows the measurement and visualisation of dehydration and oxidation processes, phase transformations (Wahl et al., 1961; Montanari, 2004; Zamporti et al., 2012), reaction processes and crystallite growth (Natter et al., 2001). The approach was tested on two distinct materials, i.e. raw clays used for ceramic production and phosphate minerals. Four clay samples from Westerwald (Germany) were chosen: a Fe rich illite clay, a red, a yellow and a white clay. In addition, two natural phosphate samples were selected: alluaudite [Na2MnFe2+Fe3+(PO4)3] from Townsite, Pringle, South Dakota, USA (sample TOW-01; Hatert, 2002), and triphylite [LiFe2+(PO4)] from Palermo pegmatite, New Hamshire, USA. Mineral transformation and vitrification processes were followed from 30 to 1250°C. [less ▲]

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See detailHistorical glazes (14th-16th century CE) characterization for the development of adapted restoration materials in Morocco
El Ouahabi, Meriam ULiege; El Halim, Mouhssin ULiege; Daoudi, Lahcen et al

Poster (2018, September)

Historical Islamic monuments are impressive by their artistic and fascinating architecture, and many of them therefore belong to the UNESCO world cultural heritage. Particularly, in Morocco the historical ... [more ▼]

Historical Islamic monuments are impressive by their artistic and fascinating architecture, and many of them therefore belong to the UNESCO world cultural heritage. Particularly, in Morocco the historical monuments are carefully decorated with arranged glazed ceramic pieces, called “zellige”, giving the buildings their typical and colorful appearance. The glaze performs a dual role in the decoration and protection of the surface. Unfortunately these architectural monuments lose their impressive appearance, when the glazed tiles are damaged and the glazes are chipped off (Fig.1). Through time, the influence of climate, water and environmental pollution can cause deterioration of the building materials and contribute to the chipping of the tile glazes (Tite et al., 2016, Gradmann, 2016). Unfortunately this damage affects many historical buildings worldwide, and restoration of glazes becomes urgent to save the brilliant facades from irreversible destruction. In Morocco, eight sites located in the imperial cities Fez and Marrakech, were classified as world heritage by UNESCO in the sixties. Since then, restoration campaigns are being undertaken to preserve the former architecture of these monuments. However, two recent restoration campaigns undertaken in Marrakech have been unsuccessful, because of the weakness of the tiles used. This study aims to characterize the glazes of the main historical buildings (14th-16th century CE) in the Marrakech area with the purpose of developing adapted restoration materials. This study will contribute to selecting the most appropriate glaze composition for restoration purposes. To address this issue, a total of 156 glaze samples were taken. Among these, 27 samples are original to different buildings in the Marrakech and Fez area (Saadian tombs, Bahia Palace, El Badi Palace and Medersa Ben Youssef, 14th to 16th c. CE), 11 samples are assumed to belong to a 1st restoration phase, 18 samples are assumed to belong to a 2nd restoration phase and 97 samples are derived from recent traditional zellige production. The glazes were carefully observed under a binocular to identify any damage affecting the surface of the sherds. The glaze color was determined using a Konica Minolta CM-700d spectrophotometer. Non destructive XRF devices (Thermo Fisher Scientific© Niton XL3t GOLDD) were used to determine the chemical composition of the glaze. Mineralogical phases of different color of glazes were carried out using a BrukerD8-Advance diffractometer with copper anticathode. From 14th to 16th century CE, in Marrakech area, the ceramists use a mixture of clay, sand and flux agents to manufacture glazes. The chemical composition did not highlight obvious correlation between the colors of the glazes and their compositions, except for the green colored glaze. The latter contains copper and sporadic chromium as a colorant. The historical glazes are lead glazes with Pb contents from 37 to 56%, opacified with Sn in the range 4–18%. Our results are in agreement with the composition of Islamic glazes in the Mediterranean area in general, and in Southern Spain in particular (e.g. Molera et al., 2001, Gradmann, 2016). This technology is taken up from the Roman and Byzantine imperia and then continued during the medieval Islamic culture in Morocco. The use of lead as flux, in association with alkalis, promotes the expansion properties during firing and increases the hardness of the tile and makes the color more clear. Furthermore, the glaze appears thicker with a more brilliant color, due to the high diffraction index of lead glass (Tite et al., 1998). In recent glazes, however, a decrease in lead amount is observed for the two restorations phases, reflecting the weakness of the glazed tiles mainly with the lack of any substituent of flux agent (Fig. 2a). This reduction of Pb is not associated with any supply of flux, implying the partial melting at low firing temperature and then the weakness of the glazed tile. [less ▲]

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See detailReconstructing Early Atlantic to Early Subatlantic peat-forming conditions of the ombrotrophic Misten Bog (eastern Belgium) on the basis of high-resolution analyses of pollen, testate amoebae and geochemistry
Streel, Maurice ULiege; Paillet, Marc ULiege; Beghin, Jérémie ULiege et al

in Geologica Belgica (2018), 21(3-4),

A seven metres thick peat bog (Misten, Hautes-Fagnes, Belgium) has been studied at high resolution in order to reconstruct the conditions of peat formation and evolution on the basis of pollen, testate ... [more ▼]

A seven metres thick peat bog (Misten, Hautes-Fagnes, Belgium) has been studied at high resolution in order to reconstruct the conditions of peat formation and evolution on the basis of pollen, testate amoebae analysis, and geochemistry. The sampled section of the peat bog corresponds to the most part of the Atlantic period, all the Subboreal period and the earliest Subatlantic period, i.e. a time interval between 7300 cal BP and 2000 cal BP. The identification of tie-points in the pollen assemblages recognized in a previous work (Persch, 1950) performed in the periphery of the same peat-bog, allows accurate correlation of the two sites, 460 cm thickness of peat in the central part corresponding to 230 cm thickness of peat in the periphery. The well constrained dates of the tie-points in the present work provide a more precise chronology of the events identified in Persch’s pollen diagram. A comparison of pollen data in both sites demonstrates that, as expected, the Corylus pollen rain is proportionally more important and the Quercetum mixtum pollen rain proportionally less important in the central area of the peat bog than in the periphery. The study of the testate amoebae in the central part of the peat bog is the major contribution of the present work. A stratigraphically constrained analysis resulted in the identification of five biozones, the zonation being mainly built on the fluctuations observed between Archerella (Amphitrema) flavum and Difflugia pulex. Three transfer functions have been applied and compared. Coupled with the humification values of each level, it allows a very accurate approach of the water-table level, and hence of local climatic conditions, at the time of the peat formation. Combination of pollen results and testate amoebae zonal subdivisions allows the definition, dating and interpretation of 18 rather short time intervals with an approximate duration of 200 to 300 years each. Our results validate and expand a previously published climate interpretation that combined geochemical data and a preliminary testate amoebae analysis. [less ▲]

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See detailHigh-resolution reconstruction of 8.2 ka BP event documented in Père Noël cave, southern Belgium
Allan, Mohammed ULiege; Fagel, Nathalie ULiege; van der Lubbe, H.J.L. et al

in Journal of Quaternary Science (2018)

A distinct shift in 18O,13C and trace element contents of the Père Noël (PN) stalagmite from southern Belgium revealed an abrupt climatic anomaly at 8.13±0.03 ka BP (Before Present=before 1950 AD ... [more ▼]

A distinct shift in 18O,13C and trace element contents of the Père Noël (PN) stalagmite from southern Belgium revealed an abrupt climatic anomaly at 8.13±0.03 ka BP (Before Present=before 1950 AD). This anomaly is characterized by a maximum drop in the 18O (-1.4‰ compared the mean) between 8.13 and 8.10 ka BP (±0.03). This drop of 18O coincides with a decrease in 13C and trace element (Sr, Ba and Mg) concentrations suggesting drier conditions. Our precise chronology provides the timing of the outburst of proglacial lakes Agassiz and Ojibway that caused the 18O, 13C and trace elemental anomalies at 8.13 – 8.10 ±0.03 ka BP, which corresponds to the 8.2 ka BP event. The PN stalagmite bears δ18O values in fluid inclusions that covariate with the δ18O values in calcite, suggesting that the speleothem calcite δ18O primarily reflects variations in the rainfall δ18O. Comparison of PN record with different marine and terrestrial archives during the 8.2 ka BP event shows a good agreement in timing and duration suggesting that the PN speleothem can be regarded as a valuable proxy to better understand the 8.2 ka BP event. [less ▲]

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See detailReconstruction of atmospheric lead pollution during the Roman period recorded in Belgian ombrotrophic peatlands cores
Allan, Mohammed ULiege; Pinti, Daniele; Ghaleb, bassam et al

in Atmosphere (2018)

Two peat cores from two bogs were used to record changes in the atmospheric Pb accumulation rate (Pb AR) in Belgium during the Roman period. The two records were compared to assess the reliability of peat ... [more ▼]

Two peat cores from two bogs were used to record changes in the atmospheric Pb accumulation rate (Pb AR) in Belgium during the Roman period. The two records were compared to assess the reliability of peat cores as archives of atmospheric Pb deposition and to establish histories of atmospheric emissions from anthropogenic sources. To address these issues we analyzed Pb concentration and its isotopes, using ICP-MS, LA-ICP-MS and MC-ICP-MS in two peat sections, spanning 1000 yr each. Lead concentrations in the two cores range from 0.1 to 60 μg g−1, with the maxima between 15 and 60 μg g−1. The average natural background of Pb AR varies between 0.003 and 0.07 mg m-2 yr-1 and the maximum ranges from 0.7 to 1.2 mg m-2 yr-1 between 50 BC and AD 215. The highest Pb AR exceed the pre-Roman period values by a factor of 17-80. Pb isotopic composition indicates that mining and metallurgical activities were the predominant sources of pollution during the Roman period. The Pb AR and chronologies in the Belgian peat cores are consistent with those reported for other continental archives as lake sediments, peat and ice cores. [less ▲]

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See detailEvidence for solar influence in a Holocene speleothem record (Père Noël cave, SE Belgium)
Allan, Mohammed ULiege; Deliège, Adrien ULiege; Verheyden, sophie et al

in Quaternary Science Reviews (2018)

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65cm stalagmite from Belgian Père Noël cave. “Père Noël” (PN) stalagmite covers the last 12.7 ka ... [more ▼]

We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65cm stalagmite from Belgian Père Noël cave. “Père Noël” (PN) stalagmite covers the last 12.7 ka according to U/ Th dating. High spatial resolution measurements of trace elements (Sr, Ba and Mg) were done by Laser-Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Trace elements profiles were interpreted as environmental and climate changes in the Han-sur-Lesse region. Power spectrum estimators and continuous wavelet transform were applied on trace elements time series to detect any statistically significant periodicities in the PN stalagmite. Spectral analyses reveal decadal to millennial periodicities (i.e., 68–75, 133–136, 198–209, 291–358, 404–602, 912–1029 and 2365–2670 yr) in the speleothem record. Results were compared to reconstructed sunspot number data to determine whether solar signal is presents in PN speleothem. The occurrence of significant solar periodicities (i.e., cycles of Gleissberg, de Vries, unnamed 500 years, Eddy and Hallstatt) supports for an impact of solar forcing on PN speleothem trace element contents. Moreover, several intervals of significant rapid winter change were detected during the Holocene at 10.3, 9.3–9.5, around 8.2, 6.4–6.2, 4.7–4.5, and around 2.7 ka BP. Those intervals are similar to the cold winter events evidenced in different natural paleoclimate archives, suggesting common climate forcing mechanisms related to changes in solar irradiance. [less ▲]

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See detailRevalorization Of The Use Of Raw Earth In Construction Practices In Kinshasa (Democratic Republic of Congo)
Mango-Itulamya, Lavie Arsène ULiege; Fagel, Nathalie ULiege; Collin, Frédéric ULiege et al

in Wingert-Playdon, Kate (Ed.) Shaping the Quality of Life (2018, May 19)

Development is impossible without the realization of basic infrastructure and the construction of a quality habitat. Therefore, this project aims to contribute to the valuation of the clay resources of ... [more ▼]

Development is impossible without the realization of basic infrastructure and the construction of a quality habitat. Therefore, this project aims to contribute to the valuation of the clay resources of the Kinshasa region in order to develop the production of local, sustainable and energy efficient construction materials. The chosen region is justified by the abundance of clay raw materials and by important needs. The Kinshasa region is facing strong spatial and demographic expansion with, as consequence, the development of a suburban area in which the habitat quality is a critical problem. Since the early 1990 and the bankruptcy of the Kinshasa Brickyard, the abandonment of building in clay materials was systematic in Kinshasa. Nearly the whole population turned to a local material: the concrete brick. It is a brick made by manual or mechanical compression by mixing grinding fines of a sandstone rock (the Inkisi sandstone) locally called “dust”, alluvial sands (alluvial deposits of the Congo River or the Mbinza, Kalamu and Ndjili rivers) and cement. These concrete bricks of 10, 15 or 20 kilograms cost on average 1, 1.5 and 2 $ the brick. Despite this high cost for most households, the concrete brick architecture is almost the only present in Kinshasa. Earth bricks (even in terra-cotta) are considered poor materials and low resistance materials. People prefer big concrete bricks, which they consider to be more aesthetic and stronger. In addition, the lack of masons trained to build with other types of materials complicates the implementation of another construction method in the region. This is a challenge that seeks to overcome a brickyard which has just been created in the nearby province of the Central Congo. I have participated in providing solutions to that challenge. The brickyard tries to diversify its products by offering a compressed earth block (CEB) made on earth-sand and earth-sand-cement to suburban and disadvantaged populations. The idea is to put forward the ecological, economic and comfort benefits of earthen habitat. To achieve this, compressed earth blocks (CEB) were produced locally in Kinshasa by a manual press. The dimensions of the manufactured CEB have been adapted to be closer to those of concrete bricks. After a period of drying, the bricks were brought to a laboratory in Belgium to undergo durability tests (accelerated erosion test and accelerated aging test) and uniaxial compression test on CEB submitted to different rates of relative humidity. This work will show how we manage to generate interest among the local population about the use of earth brick based on scientific researches aiming to produce a quality building material. [less ▲]

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See detailThe raw earth brick: a building material to meet the needs of local populations
Mango-Itulamya, Lavie Arsène ULiege; Courtejoie, Fabienne ULiege; Fagel, Nathalie ULiege

in Wingert-Playdon, Kate (Ed.) Shaping the Quality of Life (2018, May 18)

This study tests the ways of improving compressed earth bricks by the addition of sugar cane bagasse, alluvial sand and fine aggregates. The objective is to contribute to the valorization of clay ... [more ▼]

This study tests the ways of improving compressed earth bricks by the addition of sugar cane bagasse, alluvial sand and fine aggregates. The objective is to contribute to the valorization of clay resources, with the aim of developing the production of sustainable, local and energy-saving building materials, particularly in the peri-urban areas of Kinshasa in D.R.Congo. Two raw clays were characterized and then mixed with the different additives to obtain raw earth bricks. Those bricks were then submitted to flexural and compression tests to evaluate their mechanical properties. The addition of 0 to 7.5% bagasse increases the flexural strength from 0.66 to 0.99MPa and the compressive strength from 2.54 to 3.14 MPa. The addition of 0 to 50% sand increases the flexural strength from 0.56 to 0.71 MPa and the compressive strength from 2.28 to 3.09 MPa. The addition of 0 to 35% of fine aggregate does not affect the flexural strength, but increases the compressive strength from 2.28 to 3,10MPa. Stabilization with sugarcane bagasse, sand or aggregates is an interesting prospect to improve by a factor of the order of 1/3 the mechanical properties of raw earth bricks. In addition the mechanical properties are also affected by environmental variation in humidity. The durability of the bricks (i.e., its resistance to water) was therefore evaluated by “the wetting drying test” after an addition of cement. The compressive strength after six cycles of wetting-drying decreases by 25% for the bagasse mixture, 6% for the sand mixture and 2% for the aggregate mixture. Likely an addition of cement allows to significantly increase the durability. [less ▲]

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See detailDating young stalagmite using 210Pb excess method: example from Han-sur-Lesse cave, Belgium
Ghaleb, Bassam ULiege; Allan, Mohammed ULiege; verheyden, sophie et al

Conference (2018, April 12)

Speleothem cave deposits (particularly stalagmites) represent often high–resolution continental records for reconstruction of paleoclimate and/or paleoenvironmental conditions through their trace elements ... [more ▼]

Speleothem cave deposits (particularly stalagmites) represent often high–resolution continental records for reconstruction of paleoclimate and/or paleoenvironmental conditions through their trace elements concentrations (e.g., Mg, Sr and Ba) and stable isotopes compositions 18O and 13C (Fairchild, et al., 2000, 2001; McDermott, 2004). The advantage of using very young speleothems (1-120 yrs timescale) is the possibility to validate such reconstructions when compared with historical and instrumental records (e.g., meteorological parameters). U-series radiochronology remains the most suitable method to obtain reliable absolute ages of speleothems even for relatively young deposits, avoiding uncertainties related to multiple sources of CO2. In cases of pristine and clean speleothems with relatively high U-contents, precise U/Th ages can be obtained even for very recent stalagmite (e.g., Shen et al, 2013). However, this is rarely the case because speleothems often contain low U-contents (ppb levels) and traces of detrital contaminants, which require often complicated age corrections. Such corrections result in relatively high uncertainties on the final age calculation. We present here the results of 210Pb measurements carried out on high growth rate and laminated stalagmite from Han-sur Lesse cave, southern Belgium. The 210Pb results show a clear well defined exponential with depth decreasing allowing to calculate an age-depth model. These 210Pb ages were confronted to ages of the stalagmite obtained by counting laminae and considered as true ages. The results show a good agreement between the two ages within the analytical errors and open a new potential for dating recent not laminated speleothems using 210Pb excess method. [less ▲]

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