Hervé Kouamo Tchakouté

Behavior of amorphous ferrisilicates with low weight concentration in ferric ions on the properties of metakaolin-based geopolymers

Franklin Kenne Tazune, A. Oumarou Amadou, Jean Mermoz Siéwé, Jean Jacques Kouadjo Tchekwagep, Hervé Kouamo Tchakouté, Claus H. Rüscher et 1 autre(s)

Open Ceramics

The goal of this research work is to use ferrisilicates containing low weight concentration in ferric ion (0.02 g/L) as an additive to enhance the characteristics of metakaolin-based geopolymers. The ferrisilicates were produced by adding 6.6, 13.2, 19.8, 26.4 and 33 mL of ferric ions to 10, 20, 30, 40 and 50 mL of sodium waterglass, respectively. Geopolymers were obtained by separately adding 10 wt. % of each ferrisilicate to the metakaolin. The micrographies demonstrate that the addition of 13.2 mL of Fe³⁺ ions to 20 mL of sodium waterglass results in the formation of ferrisilicate with smaller particle sizes. A maximum compressive strength of 71.59 MPa is achieved using ferrisilicate from 13.2 mL of Fe³⁺ and 20 mL of sodium waterglass. One potential methodology for the production of geopolymers involves the utilisation of ferrisilicate, which exhibits a low weight concentration of ferric ions (0.02 g/L). .

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #glass properties and applications
• #ferric

Effect of thermal activation on the physicochemical property evolution of red mud and its application in low-carbon binder preparation

Dan Zhao, Yang Ma, Jinguang Zhao, Heng Chen, Qinfei Li, João Castro-Gomes et 3 autre(s)

Journal of Building Engineering

• #bauxite residue and utilization
• #recycling and utilization of industrial and municipal waste in materials production
• #carbon fibers
• #thermal

Effects of Incorporating Ferric Ions from Hematite into Metakaolin on Microscopic Pore Structures and Compressive Strength of Geopolymers

Dimace Lionel Vofo Ngnintedem, Jean Jacques Kouadjo Tchekwagep, A. Oumarou Amadou, Hervé Kouamo Tchakouté, Ruoyu Wang, Fengzhen Yang et 3 autre(s)

Journal of Materials Engineering and Performance

• #concrete and cement materials research
• #grouting, rheology, and soil mechanics
• #building materials and conservation
• #metakaolin

Improved Interlaminar Fracture Toughness of Carbon Fiber/Epoxy/Core‐Shell Rubber Composites by Multiscale Toughening Mechanisms

Fukang Li, Ning Ding, Jean Jacques Kouadjo Tchekwagep, Martin Pengou, Hervé Kouamo Tchakouté, Qiuyue Ding et 2 autre(s)

Polymer Composites

ABSTRACT Carbon fiber reinforced polymers (CFRP) composites, prized for their outstanding mechanical properties, have garnered extensive applications across critical industries including aerospace, transportation, new energy systems, and power infrastructure. However, under increasingly demanding service environments, improving the interlaminar fracture toughness of CFRP composites has become a pivotal challenge to ensure structural integrity and longevity. The present work presents an effective design strategy to address this issue for the carbon fiber/epoxy/core‐shell rubber composite by integrating multi‐scale reinforcements. The mechanical performance of specimens with different compositions was systematically analyzed. Synergistic multi‐scale toughening mechanisms were rigorously elucidated through fracture surface morphology analysis and correlative mechanical data interpretation. The results demonstrate that incorporating short carbon fibers (SCF) into CFRP (i) and adding core‐shell rubber (CSR) to CFRP (ii) both significantly enhance the toughness. CFRP (iii), which contains both SCF and CSR, exhibits an even more pronounced toughening effect. The subsequent grafting of carboxylated multi‐walled carbon nanotubes (MWCNTs‐COOH) onto SCF, resulting in CFRP (iv) with SCF‐CNTs and CSR mixed, demonstrates superior interlaminar fracture toughness compared to CFRP (iii). Specifically, the and of CFRP (iv) increase by 12.89% and 15.46%, respectively, compared to CFRP (iii). This improvement is attributed to the strengthened interfacial bonding between MWCNTs‐COOH and the matrix through mechanical interlocking, which enhances fiber bridging and the effects of core‐shell rubber. This multi‐scale reinforcement paradigm provides critical insights into the design of damage‐tolerant CFRP composites for extreme operational scenarios, advancing their deployment in next‐generation engineering systems subjected to complex mechanical loads.

• #mechanical behavior of composites
• #fiber-reinforced polymer composites
• #carbon nanotubes in composites
• #natural rubber

Influence of adding silica sand powder on the macroscopic properties and microscopic pore structures of waste-fired clay brick-based geopolymers

Cedric M. Dieuhou, Gaëlle Ngnie, Jean Jacques Kouadjo Tchekwagep, Barbara Rodrigue Eloundou Mbole, Hervé Kouamo Tchakouté, Zihao Li et 3 autre(s)

Archives of Civil and Mechanical Engineering

• #recycling and utilization of industrial and municipal waste in materials production
• #concrete and cement materials research
• #magnesium oxide properties and applications
• #materials science

Thermal behaviour of blends kaolin-boehmite and metakaolin-boehmite based-geopolymers: physical and mechanical properties

E. Tiffo, Cyrill Joël Ngally Sabouang, M. Mouafon, Claudia C. L. Tchamo, Amadou Pountouenchi, Hervé Kouamo Tchakouté et 2 autre(s)

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.

• #concrete and cement materials research
• #recycling and utilization of industrial and municipal waste in materials production
• #magnesium oxide properties and applications
• #metakaolin

Transforming waste into sustainable insulation: A novel thermal insulation board utilizing treated rice husk ash, bagasse ash, and expanded vermiculite in calcium sulfoaluminate cement composite

Jean Jacques Kouadjo Tchekwagep, Zihao Li, Huang Shifeng, Junhao Huang, Hervé Kouamo Tchakouté

Journal of Cleaner Production

• #concrete and cement materials research
• #recycling and utilization of industrial and municipal waste in materials production
• #innovative concrete reinforcement materials
• #husk

Impact of treated sewage water on early strength development of calcium sulfoaluminate cement paste: A comparative study

Jean Jacques Kouadjo Tchekwagep, Ning Ding, Fengzhen Yang, Shoude Wang, Shifeng Huang, Zhenghe Li et 4 autre(s)

Results in Engineering

• Calcium sulfoaluminate cement (CSA) was prepared with treated sewage water · • With treated sewage water, ettringite and ye'elimite were the primary hydration products · • Paste with treated sewage water was more stable, potentially improving cement properties · • Treated sewage water use led to lower compressive strength but still met standard This study investigates the use of treated sewage water (TSW) as a substitute for fresh tap water (FTW) in concrete production using calcium sulfoaluminate (CSA) cement. The research addresses concerns about freshwater scarcity and emphasizes CSA cement's rapid setting properties, crucial for emergency constructions like military airfield recovery. The focus is on the early-age properties of CSA paste mixed with TSW, with assessments conducted at 4 hours, 1 day, and 3 days post-mixing. Key parameters, including slump, setting times, and hardened characteristics, were evaluated. TSW contained significant metal concentrations and a high pH, with total dissolved solids exceeding FTW by 67%, yet all parameters remained within acceptable limits. Analytical techniques identified ettringite (AFt) as a primary hydration product, while ye'elimite (C4A3Š) was present as a component of the unhydrated clinker in the CSA cement. Simulations showed improved stability in the TSW-CSA interface compared to FTW, although early hydration was slower, likely due to delayed C4A3Š hydration and increased AFt formation. Initially, CSA/TSW pastes presented a refined microstructure, which altered by 3 days. Despite a 14% faster final setting time, compressive strength was 21% lower at 4 hours. These findings highlight TSW's potential as a sustainable alternative in CSA cement mixing, necessitating further research for long-term performance evaluation.

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #recycled aggregate concrete performance
• #cement

Improving the frost-resistance performance of supersulfated cement by reducing the crystalline-to-gel ratio through the addition of nano-SiO2

Ruoyu Wang, Beibei Li, Heng Chen, Qinfei Li, Yongbo Huang, Piqi Zhao et 4 autre(s)

Construction and Building Materials

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #microbial applications in construction materials
• #frost (temperature)

Influence of CaO/Al2O3 molar ratio of synthetic calcium aluminate hydrates on the engineering properties of metakaolin-based alkali-activated materials

Aimard Manfred Njawa Moudio, Ismailla Hamed Riyap, Jean Mermoz Siéwé, Hervé Kouamo Tchakouté, Charles Péguy Nanseu‐Njiki, Claus H. Rüscher et 1 autre(s)

Discover Civil Engineering

This study evaluates the influence of the CaO/Al 2 O 3 molar ratio of synthetic calcium aluminate hydrates on the properties of alkali-activated materials based on metakaolin. Calcium aluminate hydrates with CaO/Al 2 O 3 molar ratios of 0.4, 0.6, 0.8, 1.0 and 1.2 were synthesised from bauxite and eggshells. Alkali-activated materials were prepared in which metakaolin was replaced by 0 and 10 wt.% calcium hydroxide and calcium aluminate hydrate with different CaO/Al 2 O 3 molar ratios. Rice husk ash with a SiO 2 /Na 2 O molar ratio of 1.6 was used for the preparation of the hardener. The 28-day compressive strengths of alkali-activated materials containing 0 and 10 wt.% calcium aluminate hydrate with different CaO/Al 2 O 3 molar ratios of 0, 0.4, 0.6, 0.8, 1.0 and 1.2 are 48.86, 63.59, 47.36, 47.89, 34.66 and 32.76 MPa, respectively. 22.08 MPa for that containing 10% by weight of calcium hydroxide. The apparent densities are 1.87, 1.79, 1.99 and 2.10 g/cm 3 , respectively. It has been found that the best molar ratio of CaO to Al 2 O 3 in the structure of the 10% by weight of calcium aluminate hydrate used to replace metakaolin, which is required to produce alkali-activated materials with higher mechanical and physical properties, is about 0.4. Highlights Calcium aluminate hydrates (CAHs) with molar ratio CaO/Al 2 O 3 of 0.4, 0.6, 0.8, 1.0 and 1.2 were prepared using calcined bauxite, calcined eggshell and distillated water. Calcium hydroxide (CH) was prepared using calcined eggshell and distillated water. Metakaolin was substituted by 0 and 10 wt.% of CH and the different CAHs. The highest strength was archived at 63.59 MPa for alkali-activated material using CAH with molar ratio CaO/Al 2 O 3 of 0.4 as additive.

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #metakaolin

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

Cedric M. Dieuhou, Hervé Kouamo Tchakouté, Alexis Ngueteu Kamlo, Charles Péguy Nanseu‐Njiki, Claus H. Rüscher

Engineering Science & Technology

The main objective of the present study is the investigation of the behaviour of starch powder incorporated at different levels (0, 5, 10, 15, 20, 25, and 30 wt%) on the compressive strength and microstructural properties of metakaolin-based geopolymers. Sodium silicate with a molar ratio of SiO2/Na2O of 1.6 was used as the hardener and standard metakaolin was used as the aluminosilicate source. The results showed that when metakaolin was replaced by starch from 0 to 15 wt%, the compressive strength increased from 36.50 to 64.12 MPa. When metakaolin was replaced by starch above 15 wt%, the compressive strength decreased from 64.12 to 29.43 MPa. That of the reference geopolymer material is 36.50 MPa.The infrared spectra of the geopolymer composites indicate that the Si-O-C bonds are formed. The thermal behaviour of geopolymer composites containing starch shows a mass loss at around 100 and 278 °C. The geopolymer material without starch only shows a loss of mass at around 100 °C. The micrographs of the geopolymer composite with 15% by weight of starch show that the matrix is more compact, more homogeneous, and denser than the one without starch. On the contrary, possibly due to a large amount of unreacted starch in its network, the micrographs of the geopolymer composite obtained after the incorporation of 30 wt% starch show a heterogeneous microstructure. It can be concluded that suitable starch content for the synthesis of geopolymer composites would be around 15% by weight.

• #concrete and cement materials research
• #grouting, rheology, and soil mechanics
• #polymer science and applications
• #metakaolin

Investigation of the Properties of Metakaolin-Based Geopolymer Materials Using Ferrisilicates as Additives Synthesised in Sodium Hydroxide Solution or Distilled Water

Franklin Kenne Tazune, Lucile Dolly Dedzo Nzangue, Alexis Ngueteu Kamlo, Hervé Kouamo Tchakouté, Claus H. Rüscher

Engineering Science & Technology

The main objective of this work is to investigate the behaviour of ferrisilicates prepared from hematite and two silica sources (rice husk ash and silica fume) on the compressive strength of geopolymer materials. Some ferrisilicates were synthesised in 2M sodium hydroxide solution. Others were prepared using distilled water as a solvent. The Fe2O3/SiO2 molar ratio contained in the ferrisilicates is set to 0.2. Metakaolin and sodium silicate solution with a molar ratio of SiO2/Na2O of 1.6 were used as the aluminosilicate and hardener in this work. The control geopolymer compressive strength is 53.34 MPa. For ferrisilicates prepared in alkaline solution using rice husk ash and silica fume, their compressive strength values are 71.91 and 77.72 MPa, respectively. The compressive strengths of the geopolymer materials made from ferrisilicates prepared in distilled water using rice husk ash and silica fume are 74.13 and 44.73 MPa, respectively. In the presence of ferrisilicate obtained by dissolving silica fume and hematite in sodium hydroxide solution, the maximum compressive strength of 77.72 MPa was obtained. When ferrisilicates from the mixture of silica fume, hematite, and distilled water are used as an additive, the minimum compressive strength of 43.73 MPa is achieved. It can be concluded that additives synthesised in an alkaline medium and those obtained in distilled water with rice husk ash improve compressive strength. On the other hand, the compressive strength of the geopolymer material that uses the additive produced with silica fume in distilled water is lower (44.73 MPa).

• #concrete and cement materials research
• #grouting, rheology, and soil mechanics
• #metakaolin
• #geopolymer

Microstructure and Compressive Strength of Geopolymer Materials Based on Metakaolin with Hematite and Magnetite Gels as Additives

Dimace Lionel Vofo Ngnintedem, Jean Mermoz Siéwé, Hervé Kouamo Tchakouté, Claus H. Rüscher

Sustainable Chemical Engineering

The purpose of this work is to increase the compressive strength and improve the microstructure of geopolymer materials by adding hematite and magnetite gels, as well as their powders, cured at 80 °C. Hematite and magnetite are dissolved in 10 M sodium hydroxide. Dried gels of hematite and magnetite were then ground to produce powders of dissolved hematite and magnetite. For the production of various geopolymer materials, the metakaolin was replaced by 0 and 10 wt. % of each additive and then mixed with the hardener containing the SiO2/Na2O molar ratio set at 1.6. The results show that the reference geopolymer has a compressive strength of 51.11 MPa. These values are 50.99 and 47.59 MPa for the geopolymer materials with 10 wt. % of dissolved magnetite gel and the powder of dissolved magnetite cured at 80 °C, respectively. They are 59.52 and 63.23 MPa for those prepared using 10 wt. % of dissolved hematite gel and for the powder of dissolved hematite cured at 80 °C, respectively. Si, Al, Fe, Na and Ti form a homogeneous phase in the geopolymer structures with the exception of a few magnetite particles agglomerated in the geopolymer materials. Compressive strength was found to be improved by the use of hematite gel and dissolved hematite powder cured at 80 °C as additives. A slight reduction in the compressive strength was observed when the dissolved magnetite gel and the powder of the dissolved magnetite cured at 80 °C were used as additives.

• #grouting, rheology, and soil mechanics
• #concrete and cement materials research
• #thermal and kinetic analysis
• #geopolymer

Mineralogical evolution of raw materials transformed to geopolymer materials: A review

Sylvain Tomé, Achile Nana, Hervé Kouamo Tchakouté, Jadambaa Temuujin, Claus H. Rüscher

Ceramics International

The geopolymerization reaction is a chemical process involving the dissolution of amorphous, semi-crystalline and crystalline phases following alkaline or acid attack at ambient or at low temperature (T˂100 °C). Together with precondensed entities of the used activator solution the dissolved parts form a geopolymer network which glues together all remaining unreacted parts as ingredients of the artificial stone. The fate of the mineralogical phases present in the precursors used in the synthesis of alkaline and acid geopolymers is reviewed in this article. The different starting materials used in the synthesis of geopolymers and the different techniques used to modify the reactivity of these materials are reported. The mineralogical evolution of the amorphous, semi-crystalline and crystalline phases after activation at ambient and at low temperatures (T < 100 °C) is also reported. This study shows that for the mineralogical investigation of raw material, precursors and geopolymers, XRD is the most widely used analytical method. The most commonly used method to confirm the participation of crystalline phases in geopolymerization is the comparison of the diffractograms of the raw material to those of the products. It also indicates that, in addition to the amorphous aluminosilicate phases, certain semi-crystalline, and crystalline phases participate in this geopolymerization dynamic either by undergoing total or partial dissolution to form an inorganic macromolecule with an amorphous structure of the zeolitic type and other new minerals. The composition of the phases formed depends on the base material. Increasing the synthesis temperature promotes the dissolution of phases, the formation of geopolymer networks, and in some cases, the formation of new phases such as sodalities, zeolite A and zeolite P. Little work has been done to quantify the mineralogical phases before and after precursor activation, making it impossible to assess dissolution, the degree of geopolymerization, and mineral formation. The exact structure of the phases formed is often questionable, as most of the papers do not mention their reference structure number. There is also a lack of quantification of the amorphous phase resulting from the hardening of the activating solution and the evaluation of the fraction of the amorphous phase contained in the precursor remains unreacted. The mineralogical investigation must also extend to the quantification of phases using Rietveld refinement with internal standards to correlate these with the physical and mechanical properties of geopolymer products. Additional mineralogical study techniques, such as thin sections, should be used in future work for in-depth mineralogical investigation of geopolymers.

• #concrete and cement materials research
• #building materials and conservation
• #magnesium oxide properties and applications
• #geopolymer

Synthesis of a Hematite‐Geopolymer Composite: Optimization of Formulation Parameters and Application to the Detection of Pb 2+ Ions in Aqueous Solution

Michèle Boutianala, Martin Pengou, Guy Bertrand Piegang Ngassa, Pengkun Hou, Jean Jacques Kouadjo Tchekwagep, Hervé Kouamo Tchakouté et 2 autre(s)

Electroanalysis

Abstract The Composite Centered Experimental Design (CCED) using the response surface methodology was used to optimize the synthesis of a hematite‐geopolymer composite, applied to the preparation of a Pb 2+ electrochemical sensor. Two important experimental parameters in the formulation (curing time and hematite content) were considered in the optimization of the synthesis of the composite material. The electrochemical signal of Pb 2+ at a carbon paste electrode modified by the synthesized composite was used as a response to identify the best formulation. After applying the generated experimental plan, the optimal composite material was obtained using 17.08% hematite and a curing time of 0.16 days. The characterization of the optimized composite material revealed the presence of a porous structure and a poly(phospho‐ferro‐siloxo) network, but with a fraction of well dispersed and unreacted hematite. Preliminary experiments confirmed that the sensor prepared with the composite showed high stability and reproducibility of the Pb (II) signal, justifying its application for accurate sensing of the metal cation in an aqueous solution. A Pb 2+ calibration curve was obtained after optimizing the experimental detection parameters (composition of the carbon paste electrode, pH of the accumulation solution, accumulation time, and electrolysis potential). A detection limit of 0.2 nM (based on a signal‐to‐noise ratio of 3) was obtained for a studied concentration range between 0.04 and 0.48 nM. The designed sensor also showed remarkable selectivity and excellent performance in real media samples (spring, tap, rain, and well water).

• #electrochemical analysis and applications
• #analytical chemistry and sensors
• #smart materials for construction
• #hematite

Thermal Activation of Red Mud for the Use in Cement-Based Materials

Dan Zhao, Yang Ma, Jinguang Zhao, Chen Heng, Qinfei Li, Castro-Gomes João et 3 autre(s)

SSRN Electronic Journal

• #bauxite residue and utilization
• #red mud
• #cement
• #waste management

Use of Commercial Starch, Starches Derived from Cassava, Potato, and Yam as Additives for Synthesising Metakaolin-Based Geopolymer Composites

Cedrick Mbiakop Dieuhou, Amadou Oumarou Amadou, Hervé Kouamo Tchakouté, Charles Péguy Nanseu‐Njiki, Claus H. Rüscher, Pengkun Hou

Engineering Science & Technology

The main objective of this work is to investigate the use of different starch sources (yam, sweet potato, cassava, and commercial starch) as additives for the production of metakaolin-based geopolymer composites. Geopolymer composites were prepared by replacing metakaolin with 0 and 15 wt% of each type of starch. The different powders obtained were separately mixed with a hardener containing a molar ratio of SiO2/Na2O of 1.6. X-ray diffraction and Fourier transform infrared spectroscopy analysis were used to determine the structural properties. The compressive strength and morphology of the prepared geopolymer composites were investigated. Results show that the reference geopolymer compressive strength is 36.25 MPa. These are 64.66, 48.49, 46.03, and 44.71 MPa when commercial starch, yam starch, cassava starch, and sweet potato starch, respectively have been used as additives. It can be seen that the compressive strength values of the geopolymers containing starches are higher than those of the reference geopolymer. The compressive strength of the geopolymer composite made by replacing metakaolin with commercial starch is higher than those made with yam starch, cassava starch, and sweet potato starch. The X-ray patterns of all the geopolymers show the same mineral and the infrared spectra show the same absorption bands, except for the one at 2,935 cm-1 which appears on the spectra of the geopolymers containing starch. The geopolymer composite containing commercial starch has a more compact and dense microstructure. Those containing starches from yam, cassava, sweet potato, and the reference geopolymer material have a coarser microstructure. Compressive strength is consistent with the more compact and dense microstructure of geopolymer composite containing commercial starch. The incorporation of 15 wt% of starches derived from yam, cassava, sweet potato, and commercial starch was found to increase compressive strength. It was found that starches from various crops could be used as additives in the synthesis of geopolymer composites.

• #polymer nanocomposites and properties
• #metakaolin
• #starch
• #geopolymer

Effects of Iron Minerals on the Compressive Strengths and Microstructural Properties of Metakaolin-Based Geopolymer Materials

Dimace Lionel Vofo Ngnintedem, Marco Lampe, Hervé Kouamo Tchakouté, Claus H. Rüscher

Leibniz Universität Hannover

The current study aims to investigate the influence of iron minerals on the amorphous phase content, compressive strengths and the microstructural properties of the geopolymer materials. Geopolymer materials were prepared by the substitution of metakaolin by 10 and 20 wt.% of each iron mineral sample. Sodium waterglass from rice husk ash was used as a hardener, and metakaolin was used as an aluminosilicate source. The X-ray patterns show that the iron minerals denoted FR and FB are associated with hematite and magnetite, respectively. FY contains goethite together with a significant content of kaolinite and quartz. It is observed in the XRD patterns and FTIR absorption spectra that the additions of hematite, magnetite and goethite remain largely unreacted in the geopolymer binder. The compressive strengths of the related geopolymer composites show some significant variations indicating certain effects for mechanical stability obtained: 10 wt.% replacement of metakaolin by hematite increased the compressive strength from 51.1 to 55.5 MPa, while 20 wt.% hematite caused a decrease to 44.9 MPa. Furthermore, 10 and 20 wt.% replacement with FB revealed decreased values 47.0 and 40.3 MPa, respectively. It was also found that 10 and 20 wt.% of FY caused lower values of 30.9 and 39.1 MPa, respectively. The micrographs of geopolymer materials present some voids and cracks. The denser matrix is related to a superior gel formation producing a better glue between the crystalline additions. The unsubstituted geopolymer sample provides with about 50% the highest X-ray-amorphous content, whereas the substituted samples range between 35 and 45%, indicating systematically smaller gel contents without any clear trend with the compressive strength variation, however. The strength dependencies reveal more complex interaction between the gel and crystalline additions.

• #concrete and cement materials research
• #microbial applications in construction materials
• #clay minerals and soil interactions
• #geopolymer

Effects of Iron Minerals on the Compressive Strengths and Microstructural Properties of Metakaolin-Based Geopolymer Materials

Dimace Lionel Vofo Ngnintedem, Marco Lampe, Hervé Kouamo Tchakouté, Claus H. Rüscher

Gels

The current study aims to investigate the influence of iron minerals on the amorphous phase content, compressive strengths and the microstructural properties of the geopolymer materials. Geopolymer materials were prepared by the substitution of metakaolin by 10 and 20 wt.% of each iron mineral sample. Sodium waterglass from rice husk ash was used as a hardener, and metakaolin was used as an aluminosilicate source. The X-ray patterns show that the iron minerals denoted FR and FB are associated with hematite and magnetite, respectively. FY contains goethite together with a significant content of kaolinite and quartz. It is observed in the XRD patterns and FTIR absorption spectra that the additions of hematite, magnetite and goethite remain largely unreacted in the geopolymer binder. The compressive strengths of the related geopolymer composites show some significant variations indicating certain effects for mechanical stability obtained: 10 wt.% replacement of metakaolin by hematite increased the compressive strength from 51.1 to 55.5 MPa, while 20 wt.% hematite caused a decrease to 44.9 MPa. Furthermore, 10 and 20 wt.% replacement with FB revealed decreased values 47.0 and 40.3 MPa, respectively. It was also found that 10 and 20 wt.% of FY caused lower values of 30.9 and 39.1 MPa, respectively. The micrographs of geopolymer materials present some voids and cracks. The denser matrix is related to a superior gel formation producing a better glue between the crystalline additions. The unsubstituted geopolymer sample provides with about 50% the highest X-ray-amorphous content, whereas the substituted samples range between 35 and 45%, indicating systematically smaller gel contents without any clear trend with the compressive strength variation, however. The strength dependencies reveal more complex interaction between the gel and crystalline additions.

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #building materials and conservation
• #metakaolin

Reaction kinetics and microstructural characteristics of iron-rich-laterite-based phosphate binder

Christelle N. Bewa, Luca Valentini, Hervé Kouamo Tchakouté, Elie Kamseu, Jean Noël Yankwa Djobo, Maria Chiara Dalconi et 2 autre(s)

Construction and Building Materials

• #magnesium oxide properties and applications
• #materials engineering and processing
• #concrete and cement materials research
• #phosphoric acid

Geopolymer cement–modified carbon paste electrode: application to electroanalysis of traces of lead(II) ions in aqueous solution

Martin Pengou, Guy Bertrand Piegang Ngassa, Michèle Boutianala, Hervé Kouamo Tchakouté, Charles Péguy Nanseu‐Njiki, Emmanuel Ngameni

Journal of Solid State Electrochemistry

• #electrochemical analysis and applications
• #analytical chemistry and sensors
• #smart materials for construction
• #detection limit

Influence of alumina on the compressive strengths and microstructural properties of the acid-based geopolymers from calcined indurated laterite and metakaolin

Hervé Kouamo Tchakouté, Christelle N. Bewa, Daniel Fotio, Cedric M. Dieuhou, Elie Kamseu, Claus H. Rüscher

Applied Clay Science

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #metakaolin

Influence of the synthetic calcium aluminate hydrate and the mixture of calcium aluminate and silicate hydrates on the compressive strengths and the microstructure of metakaolin-based geopolymer cements

Aimard Manfred Njawa Moudio, Hervé Kouamo Tchakouté, Dimace Lionel Vofo Ngnintedem, Fernanda Andreola, Elie Kamseu, Charles Péguy Nanseu‐Njiki et 2 autre(s)

Materials Chemistry and Physics

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #metakaolin

Particles size and distribution on the improvement of the mechanical performance of high strength solid solution based inorganic polymer composites: A microstructural approach

Achile Nana, Elie Kamseu, Ange‐Therese Akono, Jean Ngouné, Jean Noël Yankwa Djobo, Hervé Kouamo Tchakouté et 2 autre(s)

Materials Chemistry and Physics

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #materials science

Physical properties and microstructures of poly(phospho-siloxo) and poly(sialate-siloxo) networks from two metakaolins

Charles Banenzoué, Christelle N. Bewa, Daniel Fotio, Hervé Kouamo Tchakouté, B. T. Tchanga, Claus H. Rüscher

Journal of the Korean Ceramic Society

• #concrete and cement materials research
• #recycling and utilization of industrial and municipal waste in materials production
• #bone tissue engineering materials
• #materials science

Pore Analysis and the Behaviour of the Unreacted Metakaolin Particles in the Networks of Geopolymer Cements Using Metakaolins From Kaolinitic and Halloysitic Clays

Sorelle J.K. Melele, Hervé Kouamo Tchakouté, Charles Banenzoué, Eva Lunine Hseumou, Charles Péguy Nanseu‐Njiki, Claus H. Rüscher

Silicon

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #building materials and conservation
• #metakaolin

Removal of lead ions from aqueous solution using phosphate‐based geopolymer cement composite

Jacques Romain Njimou, Martin Pengou, Hervé Kouamo Tchakouté, Mary Sieugaing Tamwa, Chedly Tizaoui, Ulrich Fannang et 3 autre(s)

Journal of Chemical Technology & Biotechnology

Abstract BACKGROUND Water contaminated by heavy metals has many negative impacts on human health and the environment. According to the UN's sustainable development goals, preserving natural resources will have positive impacts on living conditions by reducing diseases. In this study, a novel adsorbent synthesized from phosphate‐based geopolymer cement composite material was developed and evaluated for lead removal from aqueous solutions. The developed adsorbent is made from natural resources using a facile protocol, and thus it is suitable for both developed and developing countries. RESULTS Analyses of mineralogical composition, pore‐size distribution and surface of the synthesized phosphate‐based geopolymer cement composite were performed. A microporous structure was observed from the microstructural characterization. Geopolymer cement was immobilized with sodium alginate to fabricate alginate–geopolymer cement beads (Alg/GES). The parameters influencing the adsorption process were investigated in batch mode. The obtained results showed that the adsorption capacity of Pb(II) ions increased with time and equilibrium was reached in 90 min. The optimum adsorption pH was 4.17. The experimental results showed that the adsorption equilibrium of Pb(II) on Alg/GES was well described by the Freundlich and Langmuir models whereas the adsorption rate was well fitted by the pseudo‐second‐order kinetics model. The maximum adsorption capacity obtained from the Langmuir isotherm was q max = 0.38 mmol g −1 . From the Dubinin–Radushkevitch isotherm model, the value of the free adsorption energy was 41 kJ mol −1 . CONCLUSIONS Compared with other adsorbents, Alg/GES exhibited a greater adsorption capacity confirming that the phosphate‐based geopolymer cement can be suitable for removal of heavy metals from wastewaters. © 2021 Society of Chemical Industry

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #adsorption and biosorption for pollutant removal
• #adsorption

Semi-Adiabatic Calorimetry to Determine the Temperature and the Time of the Formation of Faujasite and Geopolymer Gels in the Composites Prepared at Room Temperature and the Investigation of the Properties of the Hardened Composites

Hervé Kouamo Tchakouté, Sorelle J.K. Melele, Charles Péguy Nanseu‐Njiki, Claus H. Rüscher

Silicon

• #concrete and cement materials research
• #zeolite catalysis and synthesis
• #clay minerals and soil interactions
• #materials science

Structural and Physico-mechanical Investigations of Mine Tailing-Calcined Kaolinite Based Phosphate Geopolymer Binder

Sylvain Tomé, Christelle N. Bewa, Achile Nana, Juvenal Giogetti Deutou Nemaleu, Marie Annie Etoh, Hervé Kouamo Tchakouté et 2 autre(s)

Silicon

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #geopolymer

The Coexistence of the Poly(phospho-siloxo) Networks and Calcium Phosphates on the Compressive Strengths of the Acid-Based Geopolymers Obtained at Room Temperature

Hamed I. Riyap, Franklin Kenne Tazune, Daniel Fotio, Hervé Kouamo Tchakouté, Charles Péguy Nanseu‐Njiki, Claus H. Rüscher

Journal of Inorganic and Organometallic Polymers and Materials

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #aluminate

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

Claus H. Rüscher, Ludger Lohaus, F. Jirasit, Hervé Kouamo Tchakouté

Gels

Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24° and 35° 2 Theta with maximum at about 29° 2 Theta, whereas it appears much more broadly distributed between 15° and 35° 2 Theta with maximum between 26° and 28° 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800 °C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.

• #concrete and cement materials research
• #building materials and conservation
• #recycling and utilization of industrial and municipal waste in materials production
• #metakaolin

Correction to: Utilization of geopolymer cements as supercapacitors: influence of the hardeners on their properties

Martin Pengou, Bertrand Ngouné, Hervé Kouamo Tchakouté, Charles P. N. Nanseu, Emmanuel Ngameni

SN Applied Sciences

• #supercapacitor materials and fabrication
• #geopolymer
• #supercapacitor
• #psychology

Innovative porous ceramic matrices from inorganic polymer composites (IPCs): Microstructure and mechanical properties

Achile Nana, Cyriaque Rodrigue Kaze, Thamer Alomayri, Hasan Assaedi, Juvenal Giogetti Deutou Nemaleu, Jean Ngouné et 3 autre(s)

Construction and Building Materials

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #materials science

Microstructural and mechanical properties of poly(sialate-siloxo) networks obtained using metakaolins from kaolin and halloysite as aluminosilicate sources: A comparative study

Hervé Kouamo Tchakouté, Sorelle J.K. Melele, Aubin T. Djamen, Cyriaque Rodrigue Kaze, Elie Kamseu, Charles N. P. Nanseu et 2 autre(s)

Applied Clay Science

• #concrete and cement materials research
• #grouting, rheology, and soil mechanics
• #microbial applications in construction materials
• #halloysite

Preparation of low-cost nano and microcomposites from chicken eggshell, nano-silica and rice husk ash and their utilisations as additives for producing geopolymer cements

Hervé Kouamo Tchakouté, Dominique E. Tchinda Mabah, Claus H. Rüscher, Elie Kamseu, Fernanda Andreola, Maria Chiara Bignozzi et 1 autre(s)

Journal of Asian Ceramic Societies

This work aims to prepare low-cost nanocomposite and microcomposite with lower molar ratio CaO/SiO2 (0.4). Nano-silica, rice husk ash and calcined chicken eggshell have been used as silica and calcium sources. Metakaolin has been separately replaced by 0, 10 and 20 wt% of each composite in order to study their behavior on the properties of geopolymers. The hardener used is sodium waterglass from rice husk ash. The surface area of nano-silica and rice husk ash was 54.40 and 4.08 m2/g, respectively. The cumulative volumes of the control geopolymer, the ones containing 10 wt% of microcomposite and nanocomposite are 119.71, 89.92 and 110.49 mm3/g, respectively. The compressive strength of the control specimen is around 64.02 MPa. The one using 10 wt% of microcomposite was 68.97 MPa. It drops to 42.88 MPa when metakaolin was replaced by 20 wt % of microcomposite. Whereas the one using 10 wt% of nanocomposite was 30.03 MPa and it decreases to 26.05 MPa when metakaolin was substituted by 20 wt% of nanocomposite. It can be concluded that 10 wt% of microcomposite could be mixed to metakaolin for strength development and nanocomposite does not recommend to use as an additive for producing high strength of geopolymer cements.

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #metakaolin

Reaction kinetics and rheological behaviour of meta-halloysite based geopolymer cured at room temperature: Effect of thermal activation on physicochemical and microstructural properties

Cyriaque Rodrigue Kaze, Thamer Alomayri, Hasan Assaedi, Sylvain Tomé, Gisèle Laure Lecomte‐Nana, Juvenal Giogetti Deutou Nemaleu et 4 autre(s)

Applied Clay Science

• #clay minerals and soil interactions
• #concrete and cement materials research
• #nuclear materials and radiation effects
• #geopolymer

Utilization of geopolymer cements as supercapacitors: influence of the hardeners on their properties

Martin Pengou, Bertrand Ngouné, Hervé Kouamo Tchakouté, Charles P. N. Nanseu, Emmanuel Ngameni

SN Applied Sciences

• #supercapacitor materials and fabrication
• #concrete and cement materials research
• #bone tissue engineering materials
• #materials science

Influence of the molar ratios CaO/SiO2 contained in the sustainable microcomposites on the mechanical and microstructural properties of (Ca, Na)-poly(sialate-siloxo) networks

Dominique E. Tchinda Mabah, Hervé Kouamo Tchakouté, Daniel Fotio, Claus H. Rüscher, Elie Kamseu, Maria Chiara Bignozzi et 1 autre(s)

Materials Chemistry and Physics

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #building materials and conservation
• #aluminosilicate

Meta-halloysite to improve compactness in iron-rich laterite-based alkali activated materials

Cyriaque Rodrigue Kaze, Paul Venyité, Achile Nana, Deutou Nemaleu Juvenal, Hervé Kouamo Tchakouté, Hubert Rahier et 3 autre(s)

Materials Chemistry and Physics

• #concrete and cement materials research
• #clay minerals and soil interactions
• #grouting, rheology, and soil mechanics
• #halloysite

Microstructural and mechanical properties of (Ca, Na)-poly(sialate-siloxo) from metakaolin as aluminosilicate and calcium silicate from precipitated silica and calcined chicken eggshell

Flore Mpombo Tchuente, Hervé Kouamo Tchakouté, Charles Banenzoué, Claus H. Rüscher, Elie Kamseu, Fernanda Andreola et 1 autre(s)

Construction and Building Materials

• #concrete and cement materials research
• #building materials and conservation
• #magnesium oxide properties and applications
• #metakaolin

Microstructure and mechanical, physical and structural properties of sustainable lightweight metakaolin-based geopolymer cements and mortars employing rice husk

Hamed I. Riyap, Christelle N. Bewa, Charles Banenzoué, Hervé Kouamo Tchakouté, Claus H. Rüscher, Elie Kamseu et 2 autre(s)

Journal of Asian Ceramic Societies

This work focuses on an in-depth investigation of the formation of pores in the structure of lightweight geopolymer cements and mortars using rice husk as a foaming agent. The hardener used in this study was sodium waterglass. Metakaolin was replaced by 0, 10, 20, 30 and 40 % by mass of husk and the obtained powders were used to produce lightweight geopolymer cements and mortars. The formation of pores in the lightweight geopolymer cements was monitored using X-ray diffractometry and infrared spectroscopy while those in the mortars were assessed using apparent density and compressive strength measurements, mercury intrusion porosimetry and optical and scanning electron microscopy. The values for the compressive strength and apparent density were in the ranges of 28.92–0.75 MPa and 1.88–1.70 g/cm3, respectively. The results indicated that the values for the compressive strength and apparent density of geopolymer mortars decreased while those of the cumulative pore volume increased with increases in the metakaolin replacement level. Stereomicroscopic and scanning electron microscopic images showed the presence of rice husk and fibres of rice husk, respectively, in the networks. It was found that rice husk can be used as a foaming agent for producing sustainable lightweight geopolymer mortars.

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #innovations in concrete and construction materials
• #metakaolin

Production of Porous Poly(phospho-siloxo) Networks for Thermal Insulations Using Low-Value Calcium-Rich Wastes as Pore-Forming Agents

Hervé Kouamo Tchakouté, Christelle N. Bewa, Nadine A. Kesseng, Claus H. Rüscher, Elie Kamseu, Fernanda Andreola et 2 autre(s)

Waste and Biomass Valorization

• #bone tissue engineering materials
• #biodegradable polymer synthesis and properties
• #aerogels and thermal insulation
• #eggshell

Investigation of the relationship between the condensed structure and the chemically bonded water content in the poly(sialate-siloxo) network

Sorelle J.K. Melele, Hervé Kouamo Tchakouté, Charles Banenzoué, Elie Kamseu, Claus H. Rüscher, Fernanda Andreola et 1 autre(s)

Applied Clay Science

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #building materials and conservation
• #metakaolin

Role of ɣ-Al2O3 on the mechanical and microstructural properties of metakaolin-based geopolymer cements

Hervé Kouamo Tchakouté, Elie Kamseu, Charles Banenzoué, Claus H. Rüscher, Fernanda Andreola, Claudia C. L. Tchamo et 1 autre(s)

Journal of Sol-Gel Science and Technology

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #metakaolin

Room-temperature alkaline activation of feldspathic solid solutions: Development of high strength geopolymers

Achile Nana, Jean Ngouné, Cyriaque Rodrigue Kaze, Likiby Boubakar, Serge Kouonang Tchounang, Hervé Kouamo Tchakouté et 2 autre(s)

Construction and Building Materials

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #geopolymer

Synthesis and properties of inorganic polymers (geopolymers) derived from Cameroon-meta-halloysite

Cyriaque Rodrigue Kaze, Hervé Kouamo Tchakouté, Theophile Tchakouteu Mbakop, Jacques Richard Mache, Elie Kamseu, Uphie Chinje Melo et 2 autre(s)

Ceramics International

• #clay minerals and soil interactions
• #concrete and cement materials research
• #recycling and utilization of industrial and municipal waste in materials production
• #geopolymer

The effects of synthesized calcium phosphate compounds on the mechanical and microstructural properties of metakaolin-based geopolymer cements

Hervé Kouamo Tchakouté, Daniel Fotio, Claus H. Rüscher, Elie Kamseu, Jean Noël Yankwa Djobo, Maria Chiara Bignozzi et 1 autre(s)

Construction and Building Materials

• #concrete and cement materials research
• #bone tissue engineering materials
• #magnesium oxide properties and applications
• #metakaolin

Water resistance and thermal behavior of metakaolin-phosphate-based geopolymer cements

Christelle N. Bewa, Hervé Kouamo Tchakouté, Daniel Fotio, Claus H. Rüscher, Elie Kamseu, Cristina Leonelli

Journal of Asian Ceramic Societies

The main target of this work was to investigate the thermal behavior and water resistance of geopolymer cement made from metakaolin as an aluminosilicate source using phosphoric acid solution (10 M) as a hardener. The obtained geopolymer cements were cured at room temperature for 28 days, the one part was treated at 200°C, 400°C, 600°C, 800°C and 1000°C, and the others were soaked in water for 28 days. The geopolymer cements were characterized by microstructural properties using X-ray diffractometry, infrared spectroscopy, microstructure, physical property based on water resistance and thermo-mechanical properties (thermal analysis, compressive strength). The results show that the compressive strength of the unheated geopolymer cement was 87.96 MPa. The ones soaked in water revealed a strength of 40.71 MPa. This indicates that the specimens soaked in water lose about 54% of their strengths. The X-ray patterns of heated geopolymer cements showed the formation of crystalline phases even at relatively low temperatures. It was typically found that the compressive strength of metakaolin-phosphate-based geopolymer cements decreases due to the hydrolysis of Si-O-P bonds in the presence of water.

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #innovative concrete reinforcement materials
• #metakaolin

Metakaolin‐Based Geopolymer Cements from Commercial Sodium Waterglass and Sodium Waterglass from Rice Husk Ash: A Comparative Study

Hervé Kouamo Tchakouté, Claus H. Rüscher

Ceramic engineering and science proceedings

This chapter discusses how sodium waterglass (NWG) such as commercial NWG (S1), NWG from pure rice husk ash (S2) and NWG from raw rice husk ash (S3) were used for producing geopolymer cements from metakaolin (MK) as aluminosilicate source. Commercial sodium silicates are produced from combination in varied proportions of pure quartz sand and sodium carbonate treated at approximately 1400 °C obtaining the solid sodium silicate as an amorphous material. Three sodium waterglass were prepared in an experiment with the molar ratios SiO2/Na2O and H2O/Na2O kept constant at 1.5 and 12 respectively. In order to maintain these ratios, the appropriate mass of NaOH pellets was dissolved in distilled water and then mixed with commercial sodium waterglass to obtain S1, S2 and S3 were obtained by adding NaOH pellets with powder of PRHA and RHA, respectively. The chemical compositions of kaolin (Dibo), raw rice husk ash (RHA) and pure rice husk ash (PRHA) were determined by X-ray fluorescence (XRF) using PANalytical Axios mAX. TGA of crushed geopolymer cements were performed using alumina crucible between 25-1000 °C. The resulting X-ray patterns indicate that the binder could be the same in the three cases and different only on the amount of unreacted metakaolin. These results confirm the results of water absorption which indicates that Geo3 absorbed more water in their structure and leading to the lower compressive strength.

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #husk

Moisture Control Capacity of Geopolymer Composites: Correlation of the Bulk Composition–Pore Network with the Absorption–Desorption Behavior

Elie Kamseu, Hawa Mohamed, J. C. Sofack, Duangrudee Chaysuwan, Hervé Kouamo Tchakouté, Jean Noël Yankwa Djobo et 2 autre(s)

Transport in Porous Media

• #concrete and cement materials research
• #building materials and conservation
• #recycling and utilization of industrial and municipal waste in materials production
• #materials science

The influence of gibbsite in kaolin and the formation of berlinite on the properties of metakaolin-phosphate-based geopolymer cements

Hervé Kouamo Tchakouté, Claus H. Rüscher, Elie Kamseu, Jean Noël Yankwa Djobo, Cristina Leonelli

Materials Chemistry and Physics

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #metakaolin

Utilization of sodium waterglass from sugar cane bagasse ash as a new alternative hardener for producing metakaolin-based geopolymer cement

Hervé Kouamo Tchakouté, Claus H. Rüscher, Malte Hinsch, Jean Noël Yankwa Djobo, Elie Kamseu, Cristina Leonelli

Geochemistry

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #geopolymer

Geopolymer binders from metakaolin using sodium waterglass from waste glass and rice husk ash as alternative activators: A comparative study

Hervé Kouamo Tchakouté, Claus H. Rüscher, Sakéo Kong, Elie Kamseu, Cristina Leonelli

Construction and Building Materials

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #metakaolin

Mechanical activation of volcanic ash for geopolymer synthesis: effect on reaction kinetics, gel characteristics, physical and mechanical properties

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.

• #concrete and cement materials research
• #clay minerals and soil interactions
• #building materials and conservation
• #geopolymer

Mechanical properties and durability of volcanic ash based geopolymer mortars

Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar

Construction and Building Materials

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #innovative concrete reinforcement materials
• #geopolymer

Reactivity of volcanic ash in alkaline medium, microstructural and strength characteristics of resulting geopolymers under different synthesis conditions

Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar

Journal of Materials Science

• #concrete and cement materials research
• #building materials and conservation
• #magnesium oxide properties and applications
• #materials science

Synthesis of sodium waterglass from white rice husk ash as an activator to produce metakaolin-based geopolymer cements

Hervé Kouamo Tchakouté, Claus H. Rüscher, Sakéo Kong, Navid Ranjbar

Journal of Building Engineering

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #husk

Thermal Behavior of Metakaolin-Based Geopolymer Cements Using Sodium Waterglass from Rice Husk Ash and Waste Glass as Alternative Activators

Hervé Kouamo Tchakouté, Claus H. Rüscher, Sakéo Kong, Elie Kamseu, Cristina Leonelli

Waste and Biomass Valorization

• #concrete and cement materials research
• #innovative concrete reinforcement materials
• #magnesium oxide properties and applications
• #metakaolin

Volcanic ash-based geopolymer cements/concretes: the current state of the art and perspectives

Jean Noël Yankwa Djobo, Antoine Elimbi, Hervé Kouamo Tchakouté, Sanjay Kumar

Environmental Science and Pollution Research

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #innovative concrete reinforcement materials
• #volcanic ash

Potential of using granite waste as raw material for geopolymer synthesis

Léonel Tchadjié, Jean Noël Yankwa Djobo, Navid Ranjbar, Hervé Kouamo Tchakouté, B.B.D. Kenne, Antoine Elimbi et 1 autre(s)

Ceramics International

• #concrete and cement materials research
• #magnesium oxide properties and applications
• #recycling and utilization of industrial and municipal waste in materials production
• #geopolymer