CI
Professeur
Scientific activity
Researcher profile
Faculty researcher at the University of Yaoundé I. Grade: Professeur.
Scientific publications
Bilkissou Alim, Tchedele Langollo Yannick, Belinga Essama Boum Raphael, Kagonbé Pagna Bertin, Nchare Mominou, Antoine Elimbi
Geosystems and Geoenvironment
Anne Pauline Akono Mfe’e, Florent Sikali, Paul Désiré Ndjigui, Antoine Elimbi
Geotechnical and Geological Engineering
Monique Michèle Ngo Bitty, Jean Baenla, Vivien Igor Banzouzi Samba, Jean Jacques Madiba Mboka, Marchand Joseph Manga Dika, Antoine Elimbi
Silicon
Vivien Igor Banzouzi Samba, Jean Claude Bibila Mafoumba, Loubaki Raunel, Joseph-Marie Saint Bastia MOUTOU, Antoine Elimbi
Zenodo (CERN European Organization for Nuclear Research)
The overall objective of this study is to characterize the clay soil used in the terracotta sector in the locality of Dongou. The soil texture of Dongou was determined by its particle size distribution (wet sieving). The Dongou clay was characterized by its plasticity (Atterberg limits), chemical composition (XRF), and mineralogical composition (XRF). Shrinkage before and after firing was measured. Water absorption rates and three-point bending strength were determined. Potential uses were studied. A varied grain size (Clay: 62%, Silt: 36% and Sand: 2%) giving the soil of Dongou a silty-clay texture, a mineralogy composed of Kaolinite as the predominant mineral species, quartz and other associated minerals, a chemical composition predominantly of: SiO 2 (49.92%), Al 2 O 3 (28.27%), Fe 2 O 3 (2.93%), CaO (0.13%), MgO (1.04%) with 11.1 as total loss on ignition, a plasticity index of 40% giving the clay of Dongou a very plastic nature with optimal molding, a linear shrinkage between 2 and 5%, an absorption rate between 19 and 5% beyond 1050°C, very diverse mineral transformations during firing. The clay soil of Dongou is to be used in the manufacture of lightweight block tiles.
Giovanni Dal Poggetto, Philippe Douwe, Antonio Stroscio, Elie Kamseu, Isabella Lancellotti, Antoine Elimbi and 1 more
Materials
A systematic study on the dissolution in concentrated alkali of two volcanic ashes from Cameroon, denoted as DAR and VN, is presented here. One volcanic ash, DAR, was 2 wt% richer in Fe and Ca and 4 wt% lower in Si than the other, designated as VN. Such natural raw materials are complex mixtures of aluminosilicate minerals (kaersutite, plagioclase, magnetite, diopside, thenardite, forsterite, hematite, and goethite) with a good proportion of amorphous phase (52 and 74 wt% for DAR and VN, respectively), which is more reactive than the crystalline phase in alkaline environments. Dissolution in NaOH + sodium silicate solution is the first step in the geopolymerisation process, which, after hardening at room temperature, results in solid and resistant building blocks. According to XRD, the VN finer ash powders showed a higher reactivity of Al-bearing soluble amorphous phases, releasing Al cations in NaOH, as indicated by IPC-MS. In general, dissolution in a strong alkaline environment did not seem to be affected by the NaOH concentration, provided that it was kept higher than 8 M, or by the powder size, remaining below 75 µm, while it was affected by time. However, in the time range studied, 1-120 min, the maximum element release was reached at about 100 min, when an equilibrium was reached. The hardened alkali activated materials show a good reticulation, as indicated by the low weight loss in water (10 wt%) when a hardening temperature of 25 °C was assumed. The same advantage was found for of the room-temperature consolidated specimens' mechanical performance in terms of resistance to compression (4-6 MPa). The study of the alkaline dissolution of volcanic ash is, therefore, an interesting way of predicting and optimising the reactivity of the phases of which it is composed, especially the amorphous ones.
Jean Baenla, I.B. Djon Li Ndjock, B.D. Missota Priso, Placide Désiré Belibi Belibi, Jean Baptiste Bike Mbah, Antoine Elimbi
Materials Chemistry and Physics
Manefouet Kentsa Bertille Ilalie, Véronique Kamgang Kabeyene Beyala, Valentine Katte Yato, Wouatong Armand, Jean Paul Nzenti, Paul Désiré Ndjigui and 1 more
SSRN Electronic Journal
Solomon Ndisho Tantono, Placide Désiré Belibi Belibi, Jean Baenla, Antoine Elimbi
Silicon
Olivier Mountoumnjou, Anthony Szymczyk, Emilia Lyonga, D. Njoya, Antoine Elimbi
Membranes
Safe water provision in low-income countries is constrained by limited financial resources, and the problem is worsened during natural disasters. Thus, there is a need to develop efficient low-cost technologies for point-of-use water treatment. This work reports on the development of new ceramic microfiltration membranes made from mixtures of inexpensive raw materials available locally (kaolin, bentonite and limestone) and their efficiency in rejecting bacteria such as Escherichia coli and Staphylococcus aureus. Thermogravimetric analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray diffraction, mercury intrusion porosimetry, flexural strength and water uptake were used to characterize the raw materials and membranes. The addition of limestone in the membrane fabrication increased the pore size, the porosity and, thus, the permeability of the membranes but at the expense of the rejection performance. Among the different compositions studied, the membrane made of 83% kaolin, 10% bentonite and 7% limestone showed the best performance compromise with water permeability of 566 L·h−1·m−2·bar−1 and 100% rejection of both Escherichia coli and Staphylococcus aureus. These new low-cost microfiltration membranes are expected to have potential applications in water treatment and household applications.
Emmanuel Tiffo, Placide Désiré Belibi Belibi, Jean Batiste Bike Mbah, Thamer Alomayri, Thierry Ebenizer Pougnong, Jean Baenla and 1 more
Scientific African
This study aims to improve the stability of alkali-activated products, such as powdered volcanic scoria and metakaolin, by thermal treatment in addition to their partial replacement with aluminium oxy-hydroxide. To this effect, mixtures obtained from a partial replacement of aluminosilicate sources (volcanic scoria or metakaolin) with respectively 0, 10, 20 or 30 % of mass of aluminium oxy-hydroxide were alkali-activated and stored for 28 days at room temperature in the laboratory. The various specimens obtained were heated at 900–1200 °C and both the alkali-aluminosilicates and the heated products were analysed. It appeared that aluminium oxy-hydroxide improves the stability of heated products. Thus, without replacement, alkali-activated specimens of metakaolin showed cracks at 1100 °C while those of volcanic scoria melted at 1150 °C. Conversely, heated alkali-activated specimens of either volcanic scoria or metakaolin with the replacement showed stability up to 1200 °C and an improvement in the residual compressive strength as from 900 °C. Indeed, at 1150 °C, the metakaolin-based geopolymers or the alkali-activated volcanic scoria with 30 % of mass of the replacement showed residual compressive strength of 76.7 and 35.0 MPa, respectively, due to the sintering and to the formation of new crystalline phases (mullite, corundum, carnegieite and nepheline). Yet, residual compressive strength in the alkali-activated aluminosilicate specimens with replacement that were heated at 1200 °C dropped as a result of the partial dissolution of nepheline and carnegieite which may have generated closed pores within their microstructure. Hence, alkali-activation of volcanic scoria or metakaolin partially replaced with aluminium oxy-hydroxide is a remarkable process to get thermally stable products.
B.I. Djon Li Ndjock, Jean Baenla, Jean Baptiste Bike Mbah, Antoine Elimbi, Martin Cyr
SN Applied Sciences
Claudia Charlotte Tchamo Leussa, Laurent Libessart, Chafika Djelal, Maurice Gonon, Chantale Njiomou Djangang, Antoine Elimbi
Association Universitaire de Génie Civil
L’activité pouzzolanique été étudiée sur deux types de kaolins : un kaolin du Cameroun et un kaolin Commercial afin d’élaborer un nouveau matériau de construction. Tout d’abord, après des analyses minérales et chimiques, l'étude a été faite par substitution du ciment par de l'argile de kaolinite commerciale afin d'identifier les formulations les plus intéressantes pour optimiser celles faites avec le kaolin du Cameroun. Pour ce faire, des formulations de mortier ont été réalisées et une analyse par indice d’activité a été faite à 7 et 28 jours. Dans un second temps, le kaolin commercial a été substitué par l’hydroxyde d’aluminium amorphe à 10 et 20%. Pour finir, les formulations de mortiers ont été conçues par substitutions massiques de l’argile kaolinite du Cameroun dans les mêmes conditions expérimentales. Il ressort que: i) la substitution à 10% d'hydroxyde d'aluminium amorphe dans le kaolin commercial améliore les propriétés pouzzolaniques par rapport aux autres formulations; ii) Le kaolin du Cameroun est plus pouzzolanique que toutes les autres formulations. Le kaolin du Cameroun peut donc être utilisé tel quel pour la fabrication des matériaux de construction.
E.J.A. Ndzana, D. Njoya, Antoine Elimbi, G. V. Ranaivoarivo, Gisèle Laure Lecomte‐Nana, Aubin Nzeugang Nzeukou and 1 more
Journal of Materials Science and Chemical Engineering
The aim of this study is to use Cocoa Cortex Ash (CCA) as alternative fluxing agent to manufacture vitrified ceramics at low temperatures from alluvial clay. Specimens of mixtures including clay and CCA (0%, 10%, 20% and 30% by mass) were used and fired respectively at 1050°C and 1100°C. X-ray diffraction and scanning electron microscopy were carried out. γ-alumine, mullite, akermanite, anorthite and grossular are new crystalline phases formed. Also, technological properties were determined on fired specimens as a function of CCA mass percentage. The results showed that firing shrinkage increased up to 8.5% for specimens with 10% by mass of CCA, then lessened up to 2% for specimens with 30% by mass of CCA. When fired at 1100°C, the specimens that initially contained 10% by mass of CCA allowed the formation of compact bodies with water absorption of 2% and flexural strength of 32 MPa. Hence, mixed at low percentage with poorly fluxing kaolinite clay, CCA can be used successfully as flux for the production of vitrified ceramics such as stoneware at low temperatures. The mixture of CCA with kaolinitic clay also promotes the formation of mullite and anorthite at low temperature.
Antoine Elimbi, S. Njouonkou, Julius Ndi Nsami, Placide Désiré Belibi Belibi, Joseph Ketcha Mbadkam
International Journal of Environmental Science and Technology
Dominique E. Tchinda Mabah, Hervé Kouamo Tchakouté, Claus H. Rüscher, Elie Kamseu, Antoine Elimbi, Cristina Leonelli
Materials Chemistry and Physics
Laurent Libessart, Claudia Charlotte Tchamo Leussa, Chafika Djelal, Maurice Gonon, Chantale Njiomou Djangang, Antoine Elimbi
ORBi UMONS
B.I. Djon Li Ndjock, Antoine Elimbi, Martin Cyr
Journal of Non-Crystalline Solids
D. Njoya, Antoine Elimbi, D. Fouejio, M. Hajjaji
Journal of Building Engineering
Jean Noël Yankwa Djobo, Hervé Kouamo Tchakouté, Navid Ranjbar, Antoine Elimbi, Léonel Tchadjié, Daniel Njopwouo
Journal of the American Ceramic Society
The gel composition and mechanical properties of alkali‐activated oyster shell‐volcanic ash were investigated at different NaOH concentrations (8, 12, and 15 M ) and curing temperatures (60°C and 80°C) in wet and dry conditions. XRD , FTIR , SEM ‐ EDS , and TGA ‐ DSC were used for microstructural characterization of the binder. The gel composition of the system was found to be influenced by NaOH concentration and was not affected when curing temperature was varied from 60°C to 80°C. The main phase was N,C–A–S–H for all alkali‐activated oyster shell‐volcanic ash, with C–S–H as secondary phase for some samples and contains high percentage of iron. The splitting at υ 3 = 1400–1494 cm −1 on FTIR spectra corresponded to the elimination of the degeneracy due to the distortion of CO 3 2− group. The high degree of splitting indicated that this carbonate group is linked to Ca 2+ . The compressive strength was influenced by curing temperature and the formation of a secondary phase. The compressive strength in dry condition increased roughly between 28 and 180 d for some samples, while in wet condition, the partial dissolution of Si–O–Si bonds of some silicate phases resulted in a reduction of strength.
Emmanuel Tiffo, Antoine Elimbi, Joseph Dika Manga, Arlin Bruno Tchamba
Figshare
Table S1. Composition of the mixtures of K and V expressed as mass percentage.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
Figshare
Table S1. Composition of the mixtures of K and V expressed as mass percentage.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
Figshare
Table S1. Composition of the mixtures of K and V expressed as mass percentage.
B.B. Kenne Diffo, Antoine Elimbi, Martin Cyr, Joseph Dika Manga, H. Tchakoute Kouamo
Journal of Asian Ceramic Societies
Kaolin samples of the same mass were treated at 700 °C for the same duration of 30 min by varying the rate of calcination (1, 2.5, 5, 10, 15 and 20 °C/min) in order to obtain metakaolins which were used to produce geopolymers. Depending on the nature of each type of material, kaolin, metakaolins and geopolymers were characterized using thermal analysis, chemical analysis, XRD, FTIR, particle size distribution, specific surface area, bulk density, setting time and compressive strength. FTIR and XRD analyses showed that metakaolins except at 1 °C/min contained residual kaolinite whose quantity increased with the rate of calcination of kaolin and which influenced the characteristics of geopolymers. Thus as the rate of calcination of kaolin increased, the setting time increased (226 min (rate of 1 °C/min)–773 min (rate of 20 °C/min)) while the compressive strength reduced (49.4 MPa (rate of 1 °C/min)–20.8 MPa (rate of 20 °C/min)). From the obtained results the production of geopolymers having high compressive strength along with low setting time requires that the calcination of kaolin be carried out at a low rate.
Antoine Elimbi, Hervé Kouamo Tchakouté, Masahiko Kondoh, Joseph Dika Manga
Ceramics International
Hervé Kouamo Tchakouté, Antoine Elimbi, Etienne Yanné, Chantale Njiomou Djangang
Cement and Concrete Composites
Joseph-Marie Moutou, R Mbedi, Antoine Elimbi, D. Njopwouo, Jacques Yvon, Odile Barrès and 1 more
HAL (Le Centre pour la Communication Scientifique Directe)
International audience
Hervé Kouamo Tchakouté, Antoine Elimbi, B.B.D. Kenne, Jean Aimé Mbey, D. Njopwouo
Ceramics International
Antoine Elimbi, Hervé Kouamo Tchakouté, D. Njopwouo
Construction and Building Materials
Chantale Njiomou Djangang, Elie Kamseu, Maurice Kor Ndikontar, Gisèle Laure Lecomte‐Nana, Julien Soro, Uphie Chinje Melo and 3 more
Materials Science and Engineering A
D. Njoya, M. Hajjaji, Charles Nkoumbou, Antoine Elimbi, M. Kwekam, André Njoya and 2 more
Bulletin of the Chemical Society of Ethiopia
The chemical and mineralogical characterization of raw feldspathic materials from Dschang (Cameroon) was realized by means of X-ray diffraction, differential thermal analyses, optical and scanning electron microscopies, and analytical techniques. It was found that these materials consist of albite (43 ± 3 wt.%), microcline (41 and 26 wt.%), quartz (14.5 ± 1.5 wt.%), plagioclase (oligoclase type) (6 and 12 wt.%) and a minor content of biotite. The amount of fluxing oxides is about 12 wt.% and those of pigments are quasi-null. The ceramic suitability of these materials was assessed in the light of the obtained chemical data and physical characteristics (fusibility, viscosity, colour). The results showed that these raw materials are convenient, as fluxing compounds, for manufacturing white ceramic.KEY WORDS: Raw feldspathic materials, Mineralogy, Chemical composition, Ceramic suitability, Cameroon Bull. Chem. Soc. Ethiop. 2010, 24(1), 39-46.
D. Njoya, Antoine Elimbi, Charles Nkoumbou, André Njoya, Daniel Njopwouo, Gilles Lecomte and 1 more
Annales de Chimie Science des Matériaux
Cinq echantillons de materiaux argileux denommes MY 1 , MY 2 , MY 3 , MY 4 et MY 5 , provenant du gisement argileux de Mayouom (departement du Noun, Province de l'Ouest) ont fait l'objet d'etudes granulometriques, chimiques et mineralogiques. Ces materiaux argileux sont faiblement colores et sont constitues de particules dont la fraction limoneuse est predominante. La kaolinite est leur mineral majoritaire (48-80 %). A ce dernier mineral sont associes l'illite (3-8 %), le quartz dont la teneur est elevee dans MY 1 , MY 2 , MY 4 et MY 5 (> 30 %), l'anatase (< 5 %), l'hydroxyapatite de baryum et de strontium (0-1 %), l'hematite dans MY 3 (environ 1 %) et des traces de ce dernier mineral dans MY 2 et MY 4 . Ces argiles sont exemptes d'elements toxiques (antimoine, arsenic, cadmium, bismuth). Leur composition mineralogique les predispose a des utilisations en ceramique telles que porcelaines, vitreous (produits vitrifies pour sanitaires), emaux apres lavage et elimination du quartz. Toutefois, l'echantillon MY 3 , plastique et riche en kaolinite et illite, conviendrait a l'elaboration des gres ceramiques.
Chantale Njiomou Djangang, Antoine Elimbi, U.C. Melo, Gisèle Laure Lecomte‐Nana, Charles Nkoumbou, Julien Soro and 3 more
Applied Clay Science
Emmanuel Djoufac Woumfo, Antoine Elimbi, G. Panczer, Rogatien Nyada Nyada, Daniel Njopwouo
European Journal of Control
Les vertisols preleves a differentes profondeurs sur les rives de la Benoue a Garoua ont ete etudies par diffractometrie des rayons X, analyses chimiques et analyses thermiques. Les caracteristiques telles que la capacite d'echange cationique, le taux de gonflement, l'indice de plasticite et la distribution granulaire ont ete determines. Les resultats obtenus ont montre que ces vertisols contiennent en moyenne 70 % de fraction argileuse constituee essentiellement de smectite et kaolinite, avec des mineraux associes tels que le quartz, l'ilmenite et l'orthose. Leur capacite d'echange cationique est comprise entre 35 et 42 meq./100 g et ils ont une bonne plasticite. Les compositions chimiques en elements majeurs et traces realises sur des echantillons preleves en surface et a 2,50 m de profondeur n'ont pas revele d'elements toxiques pouvant interdire leur utilisation a des fins alimentaires ou therapeutiques.
Antoine Elimbi, Stéphanie Founyapte, Daniel Njopwouo
European Journal of Control
L'etude porte sur la determination de la composition mineralogique ainsi que des proprietes physiques (retrait lineaire de cuisson, porosite et masse volumique apparentes, perte au feu) et mecaniques des produits de cuisson (600-1200°C) de deux argiles ferrugineuses et riches en mineraux fondants, provenant de Bakong, localite situee dans la province de l'Ouest du Cameroun. Pour les temperatures atteignant 900°C, les produits de cuisson offrent des valeurs elevees de porosite apparente, ce qui se traduit par des ceramiques peu denses avec de faibles resistances mecaniques. Ces resultats sont en relation avec la deshydroxylation partielle ou totale des mineraux argileux qui fait apparaitre des pores ouverts. Au dessus de 900 et jusqu'a 1200°C, les produits obtenus font apparaitre la mullite et la cristobalite et les ceramiques sont denses avec des resistances mecaniques assez elevees. Ces resultats sont en relation avec la fusion des mineraux fondants. Ces materiaux argileux peuvent etre utilises pour la production des produits de terre cuite rouge et aussi pour la formulation des ceramiques a tesson peu poreux.
Vivien Igor Banzouzi Samba, Jean Claude Bibila Mafoumba, Loubaki Raunel, Joseph-Marie Saint Bastia MOUTOU, Antoine Elimbi
Zenodo (CERN European Organization for Nuclear Research)
The overall objective of this study is to characterize the clay soil used in the terracotta sector in the locality of Dongou. The soil texture of Dongou was determined by its particle size distribution (wet sieving). The Dongou clay was characterized by its plasticity (Atterberg limits), chemical composition (XRF), and mineralogical composition (XRF). Shrinkage before and after firing was measured. Water absorption rates and three-point bending strength were determined. Potential uses were studied. A varied grain size (Clay: 62%, Silt: 36% and Sand: 2%) giving the soil of Dongou a silty-clay texture, a mineralogy composed of Kaolinite as the predominant mineral species, quartz and other associated minerals, a chemical composition predominantly of: SiO 2 (49.92%), Al 2 O 3 (28.27%), Fe 2 O 3 (2.93%), CaO (0.13%), MgO (1.04%) with 11.1 as total loss on ignition, a plasticity index of 40% giving the clay of Dongou a very plastic nature with optimal molding, a linear shrinkage between 2 and 5%, an absorption rate between 19 and 5% beyond 1050°C, very diverse mineral transformations during firing. The clay soil of Dongou is to be used in the manufacture of lightweight block tiles.
Claudia Charlotte Tchamo Leussa, Marşavina liviu, Njiomou Djangang Chantal, Galatanu Sergiu-Valentin, Cătălin Badea, Vancea Cosmin and 2 more
SSRN Electronic Journal
Anne Pauline M Akono, Florent Sikali, Paul Désiré Ndjigui, Antoine Elimbi
Research Square
Solomon T Ndisho, Ngaba Taybe, Jean Baenla, Philippe Douwe, Antoine Elimbi
Advances in Applied Ceramics Structural Functional and Bioceramics
This study determines certain characteristics of inorganic aluminosilicate polymers synthesized by alkaline and acid activations of three calcined laterites and powder of volcanic ash obtained by reciprocal progressive partial replacements, in order to compare their characteristics as earthen building materials. Firstly, the calcined laterites were partially replaced with volcanic ash before activation in the ideal alkaline and acid solutions to obtain inorganic polymer composites. Secondly, reverse replacements and activations were achieved. The results have shown that both the reactive phase content in the aluminosilicates along with the presence of certain oxides (Fe 2 O 3 and Al 2 O 3 ) are the main parameters that influence the optimization of the characteristics of the obtained composites. Hence, the partial replacement of calcined laterites by volcanic ash is detrimental to the properties of the obtained products. Compressive strength reduces averagely by 57.6% and 36.7%, respectively for alkaline and acid-activated inorganic aluminosilicate polymers obtained by substituting calcined laterites with up to 50% volcanic ash. Conversely, partial replacement of volcanic ash with calcined laterites leads to 28 days compressive strength increase from 2.0 to 12.2 MPa (alkaline medium) and from 12.5 to 23.9 MPa (acidic medium). To get the best earthen building materials, activation of calcined laterite/volcanic ash mixtures is more effective in acidic medium than in alkaline one. Also, to obtain reliable products, only an aluminosilicate material with greater reactive phase content should be used as a substitute to partially replace the one with lesser reactive phase, not the reverse.
E. Tiffo, Cyrill Joël Ngally Sabouang, M. Mouafon, Claudia C. L. Tchamo, Amadou Pountouenchi, Hervé Kouamo Tchakouté and 2 more
Open Ceramics
Thermal stability is an essential parameter to consider before using a binder at elevated temperature. This study investigates the effects of boehmite (B) on thermal behaviour and fired characteristics of sodium-based geopolymers respectively obtained from kaolin (K) and metakaolin (MK). To that end, B was used to partially replace the aluminosilicates (0 and 30 % by mass), the resulting mixtures were alkali-activated to produce geopolymers (GK, GK B 30 , GMK, GMK B 30 ), which were cured, heated (900-1100-1150°C) and characterised. Thermal behaviour revealed that B improves the thermal stability in the products of GK B 30 and GMK B 30 . Additionally, the compressive strengths were improved respectively of about 66.7 and 82.0% in GK B 30 (1100°C) and GMK B 30 (1150°C), attributed to densification coupled with the presence of mullite, corundum and quartz. These products endowed with improved fired characteristics and enhanced thermal stability can be used as binders for refractory applications as well as precursors for the production of ceramics.
Etienne Yanné, Jean Baptiste Bike Mbah, B.I. Djon Li Ndjock, Germaine Amina Wassilé, Amandine Merveille Grâce Piene Palou, Jérémie Madja Doumbaye and 1 more
World Journal of Advanced Research and Reviews
The aim of this work is to identify the chemical, mineralogical and physical properties of quartzites from the Kaélé deposit, in order to identify their potential applications. To achieve this, characterization methods such as X-ray fluorescence spectrometry and X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and a furnace for melting temperature determination were deployed. The chemical composition of the quartzites determined by X-ray fluorescence spectrometry revealed that silicon oxide (SiO2) is the majority constituent, with a mass percentage of 99.02%. The X-ray diffraction spectrum shows only quartz as the mineralogical phase present in quartzites. Quartzites have an average melting point of 1725°C, which is close to the theoretical value and makes the materials studied pure bodies. The various results obtained highlight the high purity of the quartzites from Kaélé. High-purity quartz has numerous applications in high-tech industries. The main ones are semiconductors, high-temperature lamp tubes, telecommunications and optics, microelectronics and photovoltaic cells. Kaélé quartzites can therefore be considered as highly valuable local mineral materials in the above-mentioned fields.
Kuida Tchikapa Steve Keyrane, Bélibi Bélibi Placide Désiré, Ndongo Kounou Gervais, Essomba Jean Serge, Julius Nsami Ndi, Antoine Elimbi
SSRN Electronic Journal
Claudia Charlotte Tchamo Leussa, Chantale Njiomou Djangang, Laurent Libessart, E. Tiffo, Chafika Djelal, Antoine Elimbi
HAL (Le Centre pour la Communication Scientifique Directe)
Gibbsite in tropical kaolinite material greatly influences its reactivity as pozzolanic material. The aim of this research is to study the effect of gibbsite, Al(OH)3, (15.9 mass%) on the pozzolanic activity of a kaolinite material calcined at low temperature. To this effect, the as-received raw kaolinite material was calcined at 600°C and the output product was used to partially replace Portland cement by 0, 10 and 20 mass% to produce mortars. The calcined kaolinite material was firstly subjected to the modified Chapelle test and strength activity index in order to evaluate its pozzolanic activity and physical and mechanical properties of the as-produced specimens were assessed. The results show that the calcined kaolinite material presents a high pozzolanic activity (Chappelle test = 1665 mg of Ca(OH)2/g) compared to the reference un-calcined kaolinite material (535.0 mg of Ca(OH)2/g). After 28 days of curing, mortars obtained from partial replacement with 10 mass% of the calcined kaolinite material show higher compressive strength (54.5 MPa) compared to those obtained with 20 mass% (51.3 MPa). Indeed, these values are higher compared to those of mortars produced without replacement. In fact, aluminium compound promotes the formation of metastable hydrated phases (CAH10/C2AH8) at early age which temporally hinder cement hydration. Conversely, these phases are progressively transformed into stable hydrated phases of C3AH6 with time, thereby favoring the hardening of specimens. Thus, partial replacement of Portland Cement by 10 mass% of the calcined kaolinite material is suitable to obtain mortars endowed with enhanced compressive strength for construction purpose.
Lahcen Bouna, Youssef Ettahiri, Antoine Elimbi, A. Benlhachemi, Martin Cyr
Journal of Porous Materials
Lahcen Bouna, Youssef Ettahiri, Antoine Elimbi, A. Benlhachemi, Martin Cyr
Research Square
Abstract This study investigates the importance of washing process in the quantitative improvement of both porosity and specific surface area of geopolymer. To this end, geopolymer was synthesized using natural kaolinite clay via alkaline activation. Depending on both unwashed and washed geopolymers, the following characterization techniques were achieved: X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Thermal Gravimetric Analysis (TGA), specific surface area, pore distribution, pore volume and Scanning Electron Microscopy (SEM). After the washing process, both specific surface area (S BET ) and pore volume (Vp) of geopolymers have increased considerably: S BET = 0.59 m 2 /g and Vp = 0.001 cm 3 /g (unwashed) versus S BET = 78.80 m 2 /g and Vp = 0.104 cm 3 /g (washed) respectively. Hence, the washing process allows increasing of the surface reactivity of geopolymers through the elimination among others of excess of unreacted alkaline solution which is responsible of the efflorescence.
B.I. Djon Li Ndjock, Jean Baenla, Etienne Yanné, Jean Baptiste Bike Mbah, Souaibou Souaibou, Antoine Elimbi
Materials Letters
Thierry Ebenizer Pougnong, Placide Désiré Belibi Belibi, Jean Baenla, Thamer Alomayri, Emmanuel Tiffo, Antoine Elimbi
Journal of Non-Crystalline Solids
Bernard Missota Priso Dickson, Joseph Dika Manga, Thierry Ebenizer Pougnong, Jean Baenla, Louise Ndongo Ebongue, Antoine Elimbi
Silicon
Jean Noël Yankwa Djobo, Antoine Elimbi, Dietmar Stephan
SN Applied Sciences
Abstract Phosphate geopolymers are part of chemically bonded phosphate cements obtained from an aluminosilicate and phosphate solution. Their structure consisting of phosphate bonds makes them suitable for use as refractory material. This study deals with the influence of phosphoric acid concentration (6, 8 and 10 mol/L) on the stability of volcanic ash-based phosphate geopolymers exposed to 100, 600 and 1000 °C. The results reveal that the onset of crystallization is about 600 °C with the formation of aluminum phosphate (V) and tridymite, then crystallization of iron (III) phosphate (V) and hematite at 1000 °C. The degree of crystallization of these phases increases with phosphoric acid concentration. The geopolymers obtained with 8 mol/L of phosphoric acid showed the best thermal stability at 1000 °C in terms of compressive strength change. The maximum thermal linear shrinkage recorded was 3%. The major phases of all geopolymers remain stable up to 1000 °C, after which the melting of phases happens.
B.I. Djon Li Ndjock, Rafael Robayo–Salazar, Ruby Mejía de Gutiérrez, Jean Baenla, Jean Aimé Mbey, Martin Cyr and 1 more
Journal of Building Engineering
Claudia Charlotte Tchamo Leussa, Laurent Libessart, Chafika Djelal, Chantale Njiomou Djangang, Antoine Elimbi
Scientific Reports
Abstract The addition of 10 wt% aluminum hydroxide to two crude kaolinitic clays, a commercial and a natural freshly mined one, has enhanced their pozzolanic activity, more substantially in the natural sample containing gibbsite. The obtained blends were used as replacement of 20 wt% of Portland cement in the formulations of pastes and mortars which exhibited significant decrease of setting time and increase of compressive strength from early age to 28 days. Also, SEM/EDX analyses showed very heterogeneous structures with hydrated phases identified from XRD. Specific interpretation of the role played by aluminum hydroxide revealed its aptitude to promote the formation of metastable hydrated phases (CAH 10 /C 2 AH 8 ) at early age, which temporally inhibited the hydration of cement. This progressive transformation led to the formation of more stable hydrated phases such as C–A–S–H which favored the increase of mechanical strength of the specimens. The sequence of transformation reactions is fully obtained with limited aluminum hydroxide content in clays. Either added as synthetic or naturally occurring in clays, aluminum hydroxide has close role in the strengthening process of cement. Hence, kaolinitic clays that naturally contain gibbsite are suggested as suitable supplementary cementitious material for partial replacement of cement.
Arlin Bruno Tchamba, Michel Mbessa, Tchedele Langollo Yannick, Sandra Waida, Antoine Elimbi, Uphie Chinje Melo and 1 more
Journal of Asian Ceramic Societies
The reactivity of calcium dialuminate CaAl4O7 refractory cement containing little amount of gehlenite Ca2Al2SiO7, belite Ca2SiO4, calcium aluminum iron oxide Ca3(Al,Fe)2O6 and calcium iron aluminum oxide Ca3.18Fe15.48Al1.34O28 was studied with and without Li2CO3. The granularity of the cement is d97 = 112.58 µm, d50 = 9.72 µm and d10 = 1.41 µm with water cement ratio W/C = 0.375. Little amount of Li2CO3 from 0.1wt.% to 0.6wt.% was added to the cement paste, and the result from calorimetry showed hydration mean peak time reduced from 17 h to 32 min and showed that the hydration heat of CA2 cement paste with Li2CO3 was 123 J/g lower than the one without Li2CO3 of 168 J/g. XRD of stabilized hydrates show that CaAl4O7 and Ca3(Al,Fe)2O6 participate in the hydration reaction to form C3AH6, AH3 and Ca3Al1.54Fe0.46(OH)12. The results from SEM images show nucleation site with plate-like crystal of CAH10 and small particles of AH3 forming a membrane on the cement surface.
Jean Noël Yankwa Djobo, Dietmar Stephan, Antoine Elimbi
Journal of Building Engineering
Jean Baenla, Jean Baptiste Bike Mbah, I.B. Djon Li Ndjock, Antoine Elimbi
Construction and Building Materials
Emmanuel Tiffo, Jean Batiste Bike Mbah, Placide Désiré Belibi Belibi, Jean Noël Yankwa Djobo, Antoine Elimbi
Materials Chemistry and Physics
Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar
RSC Advances
Mechanical activation is a suitable route to enhance the reactivity of volcanic ash and the final properties of the resulting geopolymers.
Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar
Construction and Building Materials
Jean Noël Yankwa Djobo, Antoine Elimbi, Joseph Dika Manga, I.B. Djon Li Ndjock
Construction and Building Materials
Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar
Journal of Materials Science
Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar
Environmental Science and Pollution Research
Yankwa Djobo Jean Noeel, Antoine Elimbi, Kouamo Tchakoute Herve, Kumar Sanjay
Construction and Building Materials
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S2. Chemical compositions of the kaolinite clay K (LOI = Loss On Ignition).
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S2. Chemical compositions of the kaolinite clay K (LOI = Loss On Ignition).
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S3. Mineralogical composition of the kaolinite clay K.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S3. Mineralogical composition of the kaolinite clay K.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S4. Chemical composition of waste glass V (LOI = Loss On Ignition).
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S4. Chemical composition of waste glass V (LOI = Loss On Ignition).
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S5. Temperature changes on the dilatometry curves of KV0 and KV2.
Emmanuel Tiffo, Antoine Elimbi, Joseph Dika Manga, Arlin Bruno Tchamba
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Table S5. Temperature changes on the dilatometry curves of KV0 and KV2.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S5. Temperature changes on the dilatometry curves of KV0 and KV2.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S6. Variation of color of samples with firing temperature.
Emmanuel Tiffo, Antoine Elimbi, Joseph Manga, Arlin Bruno Tchamba
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Table S6. Variation of color of samples with firing temperature.
Souaibou Souaibou, Joseph Mvondo Ondoa, Antoine Elimbi, Georges Emmanuel Ekodeck, Véronique Kabeyene Kamgang
European Scientific Journal ESJ
Seven samples of rocks, including three parent rock and four weathered rock from Wack (Vina division, Adamawa Region, Cameroon) have been studied. According to chemical analysis and chemical weathering indices calculated, weathering rocks conserve the structure of parent rocks. During weathering and the influence of the steep slope, the chemical elements are completely disorganized. The quantitative determination of the degree of chemical weathering of these rocks based on whole rock chemistry was performed. The slope of the straight regression absolute value is closed to 1. These various chemical weathering indices calculated has shown that they are significantly related.
Chantale Njiomou Djangang, Elie Kamseu, Claudia Charlotte Tchamo Leussa, Doretta Capsoni, Antoine Elimbi, Daniel Njopwouo
Annales de Chimie Science des Matériaux
Léonel Tchadjié, Jean Noël Yankwa Djobo, Navid Ranjbar, Hervé Kouamo Tchakouté, B.B.D. Kenne, Antoine Elimbi and 1 more
Ceramics International
Emmanuel Tiffo, Antoine Elimbi, Joseph Dika Manga, Arlin Bruno Tchamba
Brazilian Journal of Science and Technology
Red ceramics were produced at 750°C by mixing reddish yellow kaolinite clay from Marom (West Region of Cameroon) with waste glass (percentage ranging between 0 and 15% mass). Depending on the nature of the materials, kaolinite clay, waste glass and ceramics were characterized by determination of chemical and mineralogical compositions, linear shrinkage, water absorption, flexural strength and variation of color of fired samples. Thermal analysis and Fourier transform infrared spectroscopy were done as well. The final color of ceramics was red, water absorption varied between 17.40 and 13.70%, linear shrinkage ranged between 0.70 and 1.20% and flexural strength was between 5.30 and 8.10 MPa. These results showed that mixing kaolinite clay with waste glass is an interesting process to get red ceramics destined for red bricks or roofing tiles at 750°C.
Antoine Elimbi, Joseph M. Dika, Chantale Njiomou Djangang
Journal of Minerals and Materials Characterization and Engineering
Ball clay and alkaline feldspars (syenite and nepheline syenite) were mixed with red kaolinite clay (rich in iron oxides but poor in fluxing oxides) and fired (1000C -1200C) in order to improve certain characteristics of the obtained ceramics. The thermal behavior of the mixtures was monitored via Young modulus whereas linear shrinkage, water absorption, bulk density, flexural strength, microstructure and crystalline phases of fired products were examined. In the case of red clay-ball clay mixtures, the amount of mullite or cristobalite increased with heating temperature and the amount of additive, whereas the temperature at which there is an important sintering decreased with the increase of additive. In the ceramics produced from the mixtures of red clay-alkaline additive, contrary to mullite, the amount of cristobalite decreased with both the amount of additive and heating temperature. Also in the data of Young modulus, there was a decrease of temperature assigned to the beginning of densification. Additionally, incorporating at least 15% of alkaline additive to red clay and heating between 1050C and 1200C leads to ceramics with low water absorption (0.70% to 0.25%). However when using the same amount of additive and heating the mixtures at the same temperature, ceramics produced from nepheline syenite were denser than those obtained from syenite. Addition of ball clay or alkaline feldspars to kaolinite clay containing great amount of iron oxides and low fluxing oxides allows getting compact ceramics at reduced temperature.
Chantale Njiomou Djangang, Elie Kamseu, Antoine Elimbi, Gisèle Laure Lecomte‐Nana, Philippe Blanchart
Materials Sciences and Applications
In this paper, a glass powder from waste containers was mixed (10 - 40 wt.%) with a kaolinitic sandy clay from Cameroon to elaborate net-shape ceramics, fired at 1100°C. The sintering behavior was from dilatometry and thermo gravimetric analyses together with the characterization of porosity and flexural strength. The increase of glass to kaolinite ratio reduces the sintering shrinkage leading to a none-densification sintering when 40 wt.% of glass is added in the mixture. The volume variation during the whole firing process is from the individual volume variations during the quartz transformation, the structural reorganization of kaolinite and during sintering. Quartz size and relative quantity have a significant role on the first processes since it leads to either cohesive or un-cohesive behavior. But the glass quantity strongly controls the second and the third thermal processes because glass additions change the recrystallization processes, leading to the formation of dense clay-glass agglomerates distributed within the three dimensional quartz network.
Chantale Njiomou Djangang, Arlin Bruno Tchamba, Elie Kamseu, Uphie Chinje Melo, Antoine Elimbi, Anna María Ferrari and 1 more
Journal of Thermal Analysis and Calorimetry
Jean Noël Yankwa Djobo, Léonel Tchadjié, Hervé Kouamo Tchakouté, B.B.D. Kenne, Antoine Elimbi, D. Njopwouo
Journal of Asian Ceramic Societies
The aim of this work is to valorize volcanic scoria by using them as starting material for geopolymers production. Nevertheless, volcanic scoria possesses low reactivity. Various amounts of metakaolin (5%, 10%, 15%, 20% and 25%) were added into two volcanic scoria (ZD and ZG) in order to improve their reactivity. Two alkaline solutions were used to activate the aluminosilicate materials. The starting materials were characterized by particle size distribution, specific surface area, chemical and mineralogical composition. The geopolymers were characterized by the setting time, XRD, FTIR, SEM and compressive strength. The results indicated that volcanic scoria have low specific surface area (2.3 m2/g for ZD, 15.7 m2/g for ZG), high average particle size (d50 = 13.08 μm and 10.68 μm for ZD and for ZG respectively) and low glass phase contents. Metakaolin have a smaller average particle size (d50 = 9.95 μm) and high specific surface (20.5 m2/g). The compressive strength of geopolymers increased in the ranges of 23–68 MPa and 39–64 MPa for geopolymers from ZD–MK and ZG–MK respectively. This study shows that despite the low reactivity of volcanic scoria it can still be used to synthesize geopolymers with good physical and mechanical properties.
Arlin Bruno Tchamba, Antoine Elimbi, Michel Mbessa, U.C. Melo, O.M. Nzegge
Ceramics International
H. Tchakoute Kouamo, Jean Aimé Mbey, Antoine Elimbi, B.B. Kenne Diffo, D. Njopwouo
Ceramics International
H. Tchakoute Kouamo, Antoine Elimbi, Jean Aimé Mbey, Cyrill Joël Ngally Sabouang, D. Njopwouo
Construction and Building Materials
Chantale Njiomou Djangang, Gisèle Laure Lecomte‐Nana, Julien Soro, Antoine Elimbi, Philippe Blanchart, Daniel Njopwouo
Annales de Chimie Science des Matériaux
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Chantale Njiomou Djangang, Antoine Elimbi, U.C. Melo, Gisèle Laure Lecomte‐Nana, Charles Nkoumbou, Julien Soro and 3 more
Ceramics International
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