Samir BAKLOUTI - Academia.edu (original) (raw)

Papers by Samir BAKLOUTI

Eco-Efficient Repair and Rehabilitation of Concrete Infrastructures, 2018

Worldwide infrastructure rehabilitation costs are staggering. The patch repair method is widely u... more Worldwide infrastructure rehabilitation costs are staggering. The patch repair method is widely used to restore the original conditions of the concrete structures (Emmons and Vaysburd, 1994, 1996). Most patch repair mortars fall into two categories: mortars based on organic binders (epoxy resin or polyester) or those based on inorganic binders, like Portland cement (PC). The former are associated with toxic side effects (Pacheco-Torgal et al., 2012b) while the latter are known for their high embodied carbon (Pacheco-Torgal et al., 2013). Geopolymers are novel inorganic binders with a high potential to replace PC-based ones (van Deventer et al., 2012). The geopolymerization of alumino-silicate materials is a complex chemical process involving the dissolution of raw materials, transportation or orientation, and polycondensation of the reaction products (

2022 13th International Renewable Energy Congress (IREC)

Materials

In this study, undoped and (Erbium, Ytterbium) co-doped ZnO nanopowders were prepared using the s... more In this study, undoped and (Erbium, Ytterbium) co-doped ZnO nanopowders were prepared using the sol-gel method and the supercritical drying of ethyl alcohol. Doping ZnO nanopowders were elaborated with 5 mol% of Er (5 Er: ZnO), 5 mol% of Er and 5 mol% of Yb (5 Er, 5 Yb: ZnO), and 5 mol% of Er and 10 mol% of Yb (5 Er, 10 Yb: ZnO) concentrations. The effects of the Yb concentration on the structural, morphological, photoluminescent, and electrical properties of the ZnO nanopowders were investigated. The main findings of this work were the crystallinization of all of the nanopowders in a hexagonal Wurtzite structure with a spheroidal morphology and a size of 60 nm. Hence, the doping concentration would affect the crystallinity and the morphology of the ZnO nanopowder. The UC (Up-Conversion) emissions were investigated under a 980 nm excitation. It was observed that (Er, Yb: ZnO) exhibited green, ranging between 525 nm and 550 nm and red up-converted emissions of 655 nm, due to the effi...

The uniaxial compaction of spray-dried alumina containing 3 wt.% organic binders (PVA or PEG) is ... more The uniaxial compaction of spray-dried alumina containing 3 wt.% organic binders (PVA or PEG) is investigated by means of mercury porosimetry. The variation of intergranule porosity versus forming pressure is compared with the predictions of a model derived from powder metallurgy.

Russian Journal of Applied Chemistry, 2006

Modification of two samples of Tunisian clays of the type of natural smectites with organic deriv... more Modification of two samples of Tunisian clays of the type of natural smectites with organic derivatives of ammonium salts was studied. The physicochemical properties of the modified products and the possibility of their use as components of lubricating oils were analyzed.

Materialia, 2021

Abstract This study aims to present an overview of the progress of geopolymer composites with reg... more Abstract This study aims to present an overview of the progress of geopolymer composites with regards to the latest developments on its constituents (binders, activators, and aggregates) and manufacturing techniques. Some ecological, economic, and industrial limitations of the traditional aluminosilicate binders yield to the pursuit of alternative ones over the period. Some of these latest binders e.g. ferrochrome ash, mine tailings, rice husk ash, red mud, have been highlighted in this paper. Current advances on replacement of natural fine and coarse aggregates such as mine tailings (iron ore tailings), recycled/lightweight aggregates for geopolymer preparation have been reviewed from the past literature. The paper also focuses on developments regarding the new class of green alkaline and acidic activators, which is traditionally considered to be the binding agent in the preparation of geopolymer composites. Different geopolymer production methods have been briefly discussed to study their effectiveness in achieving a strong and durable composite. This paper may serve to encourage further experimental research works for achieving more sustainable, cost-effective geopolymer composites with enhanced mechanical properties.

Advances in Biochemical Engineering/Biotechnology, 2019

The phosphate ore extraction activities often generate serious environmental problems, particular... more The phosphate ore extraction activities often generate serious environmental problems, particularly those engendered by the phosphate washing waste. The waste was characterized by X ray fluorescence. The powder was calcined at 700°C. The calcined and uncalcined samples were then investigated by means of X-ray powder diffraction (XRD). The calcined PWW was activated with sodium hydroxide and sodium silicate to produce geopolymeric materials. The reached results prove to reveal that the present phases in the powder appeared to have a remarkable effect on the result of compressive strength.

Matéria (Rio de Janeiro), 2016

A reparação de estruturas degradadas de concreto representa uma oportunidade para a indústria da ... more A reparação de estruturas degradadas de concreto representa uma oportunidade para a indústria da construção mas também um desafio para a comunidade científica. O desenvolvimento de novas argamassas de reparação constitui por isso uma importante área de investigação. Os geopolímeros são ligantes inovadores alternativos ao cimento Portland pelo que as argamassas à base destes materiais, geopolíméricas, apresentam algumas potencialidades no campo da reparação das estruturas de concreto. O presente artigo apresenta resultados de uma investigação sobre o desenvolvimento de argamassas geopoliméricas à base de uma argila da Tunísia sujeita a tratamento térmico. É incluída uma análise da argila e também dos produtos de hidratação da argamassa os quais apresentam fases geopoliméricas típicas.

Ceramic Engineering and Science Proceedings, 2015

Silicates Industriels, 2009

The suitability for traditional ceramics of a clay raw material from Kasrine (Tunisia) was discus... more The suitability for traditional ceramics of a clay raw material from Kasrine (Tunisia) was discussed in view of its mineralogy and its sintering behaviour. The mineralogical composition has been estimated by combining the results of complementary techniques (X-ray diffraction (XRD), thermal analysis (DTA- TG) and ICP spectrometry). This evaluation shows that the raw material mainly consists of calcite (29 weight %) quartz (25 weight %), phlogopite (17 weight %), kaolinite (12 weight %), illite (8 weight %) and poorly crystallized goethite (4 weight %). Concerning the sintering mechanisms, the results of linear shrinkages and apparent density evolutions, X-ray diffraction analysis and ultrasonic echography lead to conclude that the product of decarbonatation of calcite (650-860°C) begins to react immediately after their formation with clayey derived materials to give mainly anorthite ((Ca,Na)(Al,Si) 2 Si 2 O 8 ) and augite (Al 0.2 Ca 0.9 Fe 0.1 Mg O 6 Si 1.8 ). This transformation should be responsible of the Young's modulus increase observed between 830 and 1100°C. The formation of a viscous liquid occurs only above 1100°C. It favors microstructure change: weak densification and pore coalescence.

Applied Clay Science, 2014

The mineralogical composition of a clay raw material picked up from a large clay deposit, located... more The mineralogical composition of a clay raw material picked up from a large clay deposit, located at Wislatiya (Tunisia) has been estimated by combining the results of different techniques (X-ray diffraction (XRD), thermal analysis (DTA-TG) and ICP spectrometry). This evaluation shows that the raw material mainly consists of quartz (30 mass %), illite (25 mass %), montmorillonite (13 mass %), kaolinite (8 mass %), carbonates (calcite and dolomite 10 mass %) and poorly crystallised goethite (7 mass %). The firing behaviour has been investigated using dilatometry and ultrasonic echography. A comparison between shrinkage and Young's modulus evolutions with temperature shows that the fast densification phenomenon which occurs between about 850 and 1075°C is linked to a structural reorganisation and that the fast shrinkage observed above 1075°C is controlled by a viscous flow-type. In addition, it was established that the low alumina content of the raw material and the extensive presence of large amounts of quartz and carbonates favour the formation of anorthite ((Ca,Na) (A1,Si) 2 Si 2 Og), which is present in the fired material immediately after decarbonatation and is still stable at 1150°C.

Ceramics Silikaty

Geopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at ... more Geopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at room or slightly higher temperature by alkaline activation of aluminosilicates obtained from industrial wastes, calcined clays and natural minerals. Among the different family of geopolymers, two Tunisian clays (a kaolinite clay from Tabarka and illito/kaolinitic clay from Medenine) are tested for their feasibility of geopolymers at low temperature. The unfired and calcined clays were dissolved in strongly alkaline solution in order to produce consolidated materials whose pastes were characterized by their compressive strength. Hardened geopolymer samples were also submitted to X-Ray diffraction, FTIR spectroscopy and scanning electron microscopy analyses. The geopolymer strength is related to the structure and reactivity of the clay generated by thermal treatment and to the role of associated minerals in clays. The amorphous character of obtained geopolymers and the displacement of the ...

Key Engineering Materials, 1997

Journal of Sol-Gel Science and Technology, 2014

Precursors are critical parameters in geopolymerization mechanisms because they govern the reacti... more Precursors are critical parameters in geopolymerization mechanisms because they govern the reaction kinetics as well as the working properties of the final materials. This study focuses on the effect of alkaline solutions on geopolymer formation. Toward this end, several geopolymer samples were synthesized from the same metakaolin and various alkaline solutions. First, the solutions were characterized by thermogravimetric analysis as well as DTA-TGA, infrared spectroscopy, and MAS-NMR spectrometry. The structural evolution of the formed geopolymers was investigated using infrared spectroscopy. The measurement of mechanical strength was tested by compression. The results provide evidence of relationships between the chemical composition, the extent of depolymerization of the alkaline solutions, the kinetics of Si-O-Si bond substitution by Si-O-Al and the compressive strength. For a given aluminosilicate source, the nature and the quantity of siliceous species in the activation solution appear to lead to variation in the reactivity and, consequently, to the formation of various networks that control the kinetics of formation of geopolymers and their mechanical properties. Keywords Si/K ratio Á Alkaline solution Á Depolymerization Á Siliceous species Á 29 Si MAS-NMR Á TEM

Handbook of Alkali-Activated Cements, Mortars and Concretes, 2015

International Journal of Material Sciences, 2013

Geopolymer is a type of cross linked long-chain inorganic compound, built in three-dimensional st... more Geopolymer is a type of cross linked long-chain inorganic compound, built in three-dimensional structures and has different attractive properties (thermal, mechanical, chemical, etc). This study elucidated the structure and mechanical properties of PSS type geopolymer obtained by alkaline attack of metakaolin. A systematic investigation was conducted to comprehend the effect of molar ratios Si/Al and Na/Al on the properties of this geopolymer by using 29Si and 27Al magnetic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, X-Ray diffraction and mechanical measurements. The results indicate that an increase of Si/Al ratio improves the geopolymer mechanical properties due probably to the formation of Si-O-Si bond in the geopolymer at the expense of Si-O-Al one. It was also shown that an introduction of NaOH in the geopolymer composition enhances the mechanical properties until a molar ratio Na/Al=1. Beyond this value, the excess of Na+ cation causes fragility of the geopolymer structure confirmed by a decrease of the mechanical strength.

Russian Journal of Applied Chemistry, 2006

Modification of two samples of Tunisian clays of the type of natural smectites with organic deriv... more Modification of two samples of Tunisian clays of the type of natural smectites with organic derivatives of ammonium salts was studied. The physicochemical properties of the modified products and the possibility of their use as components of lubricating oils were analyzed.

Eco-Efficient Repair and Rehabilitation of Concrete Infrastructures, 2018

Worldwide infrastructure rehabilitation costs are staggering. The patch repair method is widely u... more Worldwide infrastructure rehabilitation costs are staggering. The patch repair method is widely used to restore the original conditions of the concrete structures (Emmons and Vaysburd, 1994, 1996). Most patch repair mortars fall into two categories: mortars based on organic binders (epoxy resin or polyester) or those based on inorganic binders, like Portland cement (PC). The former are associated with toxic side effects (Pacheco-Torgal et al., 2012b) while the latter are known for their high embodied carbon (Pacheco-Torgal et al., 2013). Geopolymers are novel inorganic binders with a high potential to replace PC-based ones (van Deventer et al., 2012). The geopolymerization of alumino-silicate materials is a complex chemical process involving the dissolution of raw materials, transportation or orientation, and polycondensation of the reaction products (

2022 13th International Renewable Energy Congress (IREC)

Materials

In this study, undoped and (Erbium, Ytterbium) co-doped ZnO nanopowders were prepared using the s... more In this study, undoped and (Erbium, Ytterbium) co-doped ZnO nanopowders were prepared using the sol-gel method and the supercritical drying of ethyl alcohol. Doping ZnO nanopowders were elaborated with 5 mol% of Er (5 Er: ZnO), 5 mol% of Er and 5 mol% of Yb (5 Er, 5 Yb: ZnO), and 5 mol% of Er and 10 mol% of Yb (5 Er, 10 Yb: ZnO) concentrations. The effects of the Yb concentration on the structural, morphological, photoluminescent, and electrical properties of the ZnO nanopowders were investigated. The main findings of this work were the crystallinization of all of the nanopowders in a hexagonal Wurtzite structure with a spheroidal morphology and a size of 60 nm. Hence, the doping concentration would affect the crystallinity and the morphology of the ZnO nanopowder. The UC (Up-Conversion) emissions were investigated under a 980 nm excitation. It was observed that (Er, Yb: ZnO) exhibited green, ranging between 525 nm and 550 nm and red up-converted emissions of 655 nm, due to the effi...

The uniaxial compaction of spray-dried alumina containing 3 wt.% organic binders (PVA or PEG) is ... more The uniaxial compaction of spray-dried alumina containing 3 wt.% organic binders (PVA or PEG) is investigated by means of mercury porosimetry. The variation of intergranule porosity versus forming pressure is compared with the predictions of a model derived from powder metallurgy.

Russian Journal of Applied Chemistry, 2006

Modification of two samples of Tunisian clays of the type of natural smectites with organic deriv... more Modification of two samples of Tunisian clays of the type of natural smectites with organic derivatives of ammonium salts was studied. The physicochemical properties of the modified products and the possibility of their use as components of lubricating oils were analyzed.

Materialia, 2021

Abstract This study aims to present an overview of the progress of geopolymer composites with reg... more Abstract This study aims to present an overview of the progress of geopolymer composites with regards to the latest developments on its constituents (binders, activators, and aggregates) and manufacturing techniques. Some ecological, economic, and industrial limitations of the traditional aluminosilicate binders yield to the pursuit of alternative ones over the period. Some of these latest binders e.g. ferrochrome ash, mine tailings, rice husk ash, red mud, have been highlighted in this paper. Current advances on replacement of natural fine and coarse aggregates such as mine tailings (iron ore tailings), recycled/lightweight aggregates for geopolymer preparation have been reviewed from the past literature. The paper also focuses on developments regarding the new class of green alkaline and acidic activators, which is traditionally considered to be the binding agent in the preparation of geopolymer composites. Different geopolymer production methods have been briefly discussed to study their effectiveness in achieving a strong and durable composite. This paper may serve to encourage further experimental research works for achieving more sustainable, cost-effective geopolymer composites with enhanced mechanical properties.

Advances in Biochemical Engineering/Biotechnology, 2019

The phosphate ore extraction activities often generate serious environmental problems, particular... more The phosphate ore extraction activities often generate serious environmental problems, particularly those engendered by the phosphate washing waste. The waste was characterized by X ray fluorescence. The powder was calcined at 700°C. The calcined and uncalcined samples were then investigated by means of X-ray powder diffraction (XRD). The calcined PWW was activated with sodium hydroxide and sodium silicate to produce geopolymeric materials. The reached results prove to reveal that the present phases in the powder appeared to have a remarkable effect on the result of compressive strength.

Matéria (Rio de Janeiro), 2016

A reparação de estruturas degradadas de concreto representa uma oportunidade para a indústria da ... more A reparação de estruturas degradadas de concreto representa uma oportunidade para a indústria da construção mas também um desafio para a comunidade científica. O desenvolvimento de novas argamassas de reparação constitui por isso uma importante área de investigação. Os geopolímeros são ligantes inovadores alternativos ao cimento Portland pelo que as argamassas à base destes materiais, geopolíméricas, apresentam algumas potencialidades no campo da reparação das estruturas de concreto. O presente artigo apresenta resultados de uma investigação sobre o desenvolvimento de argamassas geopoliméricas à base de uma argila da Tunísia sujeita a tratamento térmico. É incluída uma análise da argila e também dos produtos de hidratação da argamassa os quais apresentam fases geopoliméricas típicas.

Ceramic Engineering and Science Proceedings, 2015

Silicates Industriels, 2009

The suitability for traditional ceramics of a clay raw material from Kasrine (Tunisia) was discus... more The suitability for traditional ceramics of a clay raw material from Kasrine (Tunisia) was discussed in view of its mineralogy and its sintering behaviour. The mineralogical composition has been estimated by combining the results of complementary techniques (X-ray diffraction (XRD), thermal analysis (DTA- TG) and ICP spectrometry). This evaluation shows that the raw material mainly consists of calcite (29 weight %) quartz (25 weight %), phlogopite (17 weight %), kaolinite (12 weight %), illite (8 weight %) and poorly crystallized goethite (4 weight %). Concerning the sintering mechanisms, the results of linear shrinkages and apparent density evolutions, X-ray diffraction analysis and ultrasonic echography lead to conclude that the product of decarbonatation of calcite (650-860°C) begins to react immediately after their formation with clayey derived materials to give mainly anorthite ((Ca,Na)(Al,Si) 2 Si 2 O 8 ) and augite (Al 0.2 Ca 0.9 Fe 0.1 Mg O 6 Si 1.8 ). This transformation should be responsible of the Young's modulus increase observed between 830 and 1100°C. The formation of a viscous liquid occurs only above 1100°C. It favors microstructure change: weak densification and pore coalescence.

Applied Clay Science, 2014

The mineralogical composition of a clay raw material picked up from a large clay deposit, located... more The mineralogical composition of a clay raw material picked up from a large clay deposit, located at Wislatiya (Tunisia) has been estimated by combining the results of different techniques (X-ray diffraction (XRD), thermal analysis (DTA-TG) and ICP spectrometry). This evaluation shows that the raw material mainly consists of quartz (30 mass %), illite (25 mass %), montmorillonite (13 mass %), kaolinite (8 mass %), carbonates (calcite and dolomite 10 mass %) and poorly crystallised goethite (7 mass %). The firing behaviour has been investigated using dilatometry and ultrasonic echography. A comparison between shrinkage and Young's modulus evolutions with temperature shows that the fast densification phenomenon which occurs between about 850 and 1075°C is linked to a structural reorganisation and that the fast shrinkage observed above 1075°C is controlled by a viscous flow-type. In addition, it was established that the low alumina content of the raw material and the extensive presence of large amounts of quartz and carbonates favour the formation of anorthite ((Ca,Na) (A1,Si) 2 Si 2 Og), which is present in the fired material immediately after decarbonatation and is still stable at 1150°C.

Ceramics Silikaty

Geopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at ... more Geopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at room or slightly higher temperature by alkaline activation of aluminosilicates obtained from industrial wastes, calcined clays and natural minerals. Among the different family of geopolymers, two Tunisian clays (a kaolinite clay from Tabarka and illito/kaolinitic clay from Medenine) are tested for their feasibility of geopolymers at low temperature. The unfired and calcined clays were dissolved in strongly alkaline solution in order to produce consolidated materials whose pastes were characterized by their compressive strength. Hardened geopolymer samples were also submitted to X-Ray diffraction, FTIR spectroscopy and scanning electron microscopy analyses. The geopolymer strength is related to the structure and reactivity of the clay generated by thermal treatment and to the role of associated minerals in clays. The amorphous character of obtained geopolymers and the displacement of the ...

Key Engineering Materials, 1997

Journal of Sol-Gel Science and Technology, 2014

Precursors are critical parameters in geopolymerization mechanisms because they govern the reacti... more Precursors are critical parameters in geopolymerization mechanisms because they govern the reaction kinetics as well as the working properties of the final materials. This study focuses on the effect of alkaline solutions on geopolymer formation. Toward this end, several geopolymer samples were synthesized from the same metakaolin and various alkaline solutions. First, the solutions were characterized by thermogravimetric analysis as well as DTA-TGA, infrared spectroscopy, and MAS-NMR spectrometry. The structural evolution of the formed geopolymers was investigated using infrared spectroscopy. The measurement of mechanical strength was tested by compression. The results provide evidence of relationships between the chemical composition, the extent of depolymerization of the alkaline solutions, the kinetics of Si-O-Si bond substitution by Si-O-Al and the compressive strength. For a given aluminosilicate source, the nature and the quantity of siliceous species in the activation solution appear to lead to variation in the reactivity and, consequently, to the formation of various networks that control the kinetics of formation of geopolymers and their mechanical properties. Keywords Si/K ratio Á Alkaline solution Á Depolymerization Á Siliceous species Á 29 Si MAS-NMR Á TEM

Handbook of Alkali-Activated Cements, Mortars and Concretes, 2015

International Journal of Material Sciences, 2013

Geopolymer is a type of cross linked long-chain inorganic compound, built in three-dimensional st... more Geopolymer is a type of cross linked long-chain inorganic compound, built in three-dimensional structures and has different attractive properties (thermal, mechanical, chemical, etc). This study elucidated the structure and mechanical properties of PSS type geopolymer obtained by alkaline attack of metakaolin. A systematic investigation was conducted to comprehend the effect of molar ratios Si/Al and Na/Al on the properties of this geopolymer by using 29Si and 27Al magnetic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, X-Ray diffraction and mechanical measurements. The results indicate that an increase of Si/Al ratio improves the geopolymer mechanical properties due probably to the formation of Si-O-Si bond in the geopolymer at the expense of Si-O-Al one. It was also shown that an introduction of NaOH in the geopolymer composition enhances the mechanical properties until a molar ratio Na/Al=1. Beyond this value, the excess of Na+ cation causes fragility of the geopolymer structure confirmed by a decrease of the mechanical strength.

Russian Journal of Applied Chemistry, 2006

Modification of two samples of Tunisian clays of the type of natural smectites with organic deriv... more Modification of two samples of Tunisian clays of the type of natural smectites with organic derivatives of ammonium salts was studied. The physicochemical properties of the modified products and the possibility of their use as components of lubricating oils were analyzed.