Juvenal Giogetti Deutou Nemaleu

Unversity of Tokyo (Department of Architecture): Tokyo, JP · Building Materials Laboratory

Anorthite-based highly porous membranes were successfully produced using calcined oyster shell to enhance the pore network. The calcined oyster shells produce CaO responsible for the crystallisation of gehlenite and anorthite at relatively low temperature. While the crystallisation produced nano and meso size of intergranular pores, vitrification o...

Owing to its availability and afordability, lateritic soils are one of common building materials widely used for the develop�ment of infrastructures in sub-tropical and tropical regions. Their engineering properties are mostly infuenced by such fac�tors including climate, vegetation, typography, and parent rock. Seeking a proper method to improve t...

The refractory alkaline activated materials gained attention in the various engineering and industrial applications due to its environmental and eco-friendly benefits. The present study deals with the evaluation of the effects of nano-ZrO2, nano-Al2O3, and nano-TiO2 particles reinforcement mechanism on the final properties of the geopolymer matrice...

The aim of this work is to study the influence of the palm fibers treated with soda hydroxide solution, on the properties of the compressed earth bricks stabilized with 15% of natural pozzolana based alkaline geopolymer binder. To achieve this objective, mortars composed of treated fibers at different levels (0.1, 0.2, 0.3, 0.4 and 0.5%) for a leng...

This study aimed to investigate the efficiency of a geopolymer binder of the type of Na-poly(ferro-silico-aluminate) as a matrix for the stabilization of heavy metals along with their effect on the development of structural performances. The artificial contamination of soil with ions was carried out and used to prepare an alkali-activated iron-rich...

Two geopolymer binder systems made under alkaline and acidic conditions have been evaluated for the stabilization of compressed lateritic earth bricks (CEBs) using natural pozzolan as aluminosilicate precursor. The preparation of alkaline and acidic activators involved the combination of sodium silicate and 10 mol/L sodium hydroxide solutions, as w...

The present work aims to evaluate the curing temperatures on the engineering and structural properties of the compressed earth blocks (CEBs) produced using natural pozzolan-based acid and alkali-geopolymers as alternative binders. A fixed 15 wt% of binder made with both acid and alkaline solution and natural pozzolan was used to stabilize the later...

Functional refractory remains critical due to its intrinsic properties such as: saving space, lightweight and excellent thermal stability to achieve the trade-off between insulating and overall performances. The present study deals with the production of low carbon footprint and lightweight refractory matrices, with controllable pores structures, t...

Laterite soils account for 70% of Cameroon territory. The present study aims to investigate the thermal behavior of geopolymer from both thermally activated lateritic clay and indurated laterite at 700°C. The resulting calcined powder was consolidated with phosphoric acid (PA) and alkaline solution (AS), and after 28 days of cure, the geopolymer th...

In the present study, the performances of the end products prepared using calcined iron-rich laterite at 600 °C (LAT600) with different alkaline solution (AS) to calcined laterite (AS/LAT600) mass ratio (0.45-0.65) were investigated. The effect of AS/LAT600 mass ratio on microstructural and mechanical properties of consolidated geopolymer samples,...

Lateritic soils are abundant materials available around the tropical and sub-tropical areas in the world. However, due to their chemical and mineralogical complexity, their use in geopolymer synthesis remains limited. This review paper summarizes the synthesis conditions, mechanical and durability characteristics as well as the microstructural pro...

The exploitation of volcanic rock quarries generates enormous waste, which causes the problem of disposal, leading to rising dust levels in quarries and depositions on nearby farms by runoffs. To address this issue, the development of sustainable solution for their valorization in construction industries is required. The present investigation aims...

This work explores the possibility of using Mine tailing (MT) as a feedstock in the synthesis of phosphate geopolymer binder. MT was activated at different concentrations of phosphoric acid (4, 6, 8, 10 and 12 M). The modification of the Si/Al weight ratio was done by the incorporation of 5, 10, 15, 20 and 25 wt% of calcined kaolinite (CK). After 2...

Understanding the structural and meso-scale properties of alkali activated matrices subjected to high temperature treatment, provides useful information on the stability of their self-life service or, fire resistance in extreme environments. The current project focuses on the transformation of phase and structural bonds within kyanite-reinforced re...

In the present study, multi-scale sized porous inorganic polymers were produced by alkaline activation of volcanic ash. Rice husk ash, an agricultural biomass, was used both in the synthesis of the alkaline activator and as pore inducing agent. Hardened porous geopolymers underwent mineralogical analysis, compressive strength and apparent density t...

Abstract The chemical stabilization of compressed earth bricks (CEB) by geopolymer binders appears nowadays as an ecological and efcient technique for the production of durable earth bricks. This work aims to evaluate the feasibility of stabilizing clayey soil-based compressed earth blocks with calcined kaolinite-based alkali-activated binder. Th...

Laterite soils are one of the promising aluminosilicate materials that can be utilized as precursors in the synthesis of geopolymers. However, it is critical to understand how the composition of the laterites and the type of activator influence the corresponding performance of geopolymer composites. Hence, this study was undertaken to evaluate the...

The present study deals with the use of locally prepared rice husk ash (RHA)-based sodium silicate for alkaline activation of laterites (uncalcined (LNW) and calcined (LCA)). RHA-based activator (SSR) was prepared by adding as-collected RHA to 6 M NaOH at a solid/liquid mass ratio of 0.56. The various proportions of metakaolin (MK) and basalt powde...

In this study, a laterite soil which is a locally available material in many parts of the world was used as the aluminosilicate precursor. The main objective of this study is to investigate the efect of calcination temperature on physicochemical properties of the resulting geopolymers synthesized from calcined laterite soils. In order to produce th...

The development of eco- friendly environmental and sustainable building materials having low thermal conductivity and optimal physic-chemical abilities ensuring passive thermal comfort is imperative in the global quest for the minimization of greenhouse-gases (GHG) emission and energy needs in homes. To attend this objective, the present work under...

Concrete structures built in granite-based aggregate develop and proliferate contour-like cracks as they aged. Such cracks are often associated to alkali-aggregate reactions (AAR). Though, in most cases, the alkali-silica reaction (ASR) involving these aggregates has shown to be non-destructive to concretes, their contents of iron-contained mineral...

The aim of the present project deals with the use of the available agricultural by-product groundnut shell ash (GSA) as replacement (0, 10, 20 and 30 wt.%) to metakaolin for the synthesis of lightweight geopolymer. Two alkaline solutions (8 and 10M) have been used as activator solution. The resulting product was characterized using XRD, FT-IR, SEM-...

In this study, an ecofriendly binder was developed by using rice husk ash (RHA) and sodium hydroxide as the activator alongside fly ash (FA) as the aluminosilicate precursor at ambient conditions. The developed binder was used in the production of mortars with varying proportions of sand. A total of three mortar mixtures were developed with sand to...

This paper investigates the direct transformation of laterites (natural iron‐rich aluminosilicates) to cementi- tious composites with principal mineral phases being Gismondine and Stratlingite. The effects of particles size distribution and cement content (2 to 8 wt%) on the mechanical properties and microstructure of laterite‐ cement composites ar...

Laterite soils are one of the promising aluminosilicate materials that can be utilized as precursors in the synthesis of geopolymers. However, it is critical to understand how the composition of the laterites and the type of activator influence the corresponding performance of geopolymer composites. Hence, this study was undertaken to evaluate the...

In this study, sugarcane bagasse fibres (SBF) were used as a sustainable alternative to reinforce laterite-based geopolymers. As geopolymers can be deemed an eco-friendly construction material, the sustainability of geopolymers can be further improved with the use of SBF which is an agricultural by-product as reinforcement. In addition, the use of...

The growing demand and use of geopolymer binders have been of high interest in recent times due to their sustainability and economic benefits. However, locally available materials must be used in the production of geopolymer binders in order to maximize their benefits. In this study, a laterite soil which is a locally available material in many par...

The present project investigated the thermal stability of cold-setting refractory composites under high-temperature cycles. The proposed route dealt with the feasibility of using fillers with different particle sizes and studying their influence on the thermo-mechanical properties of refractory geopolymer composites. The volumetric shrinkage was st...

The physical, mechanical and microstructural properties of metakaolin/volcanic ash-based geopolymer composites were investigated, as well as the influence of the incorporation of a reactive silica from rice husk ash (RHA) in their performance. The geopolymer composites were designed by replacing metakaolin with volcanic ash, VA (10-30 wt%) and RHA...

Two calcined clays (halloysite and kaolinite clays at 700 °C) were used as solid precursors for geopolymer synthesis. This study compares the physicochemical properties of the both resulting geopolymer series heated at 200, 400, 600 and 800 °C. The end specimens were characterized using Optical Dilatometer, XRD, FTIR, MIP and SEM analyses. Results...

This project aims to study the effect of ripe powdered banana peel (BP) on properties of calcined halloysite based geopolymer activated with alkaline silicate solution. Ripe powdered banana peel (BP) obtained after drying and milling banana peels was mixed with calcined halloysite (MH) at the rate of 0, 5, 10, 15 and 20 wt% by weight of binder. Set...

The thermal performance of pegmatite-based geopolymer composites is investigated. Dense and compact matrix was prepared replacing metakaolin with pegmatite in the range of 70–85 wt% and activate with sodium hydroxide/sodium silicate solution in 1:1 vol ratio. The products of geopolymerization, cured at room temperature for 28 days, were heated at 1...

The present project deals with the production of alkali activated concretes based on volcanic and calcined laterite under different curing temperatures (28-80°C). A fraction of 0-40% calcined laterite was added to improve the reactive phase content and the resulting mixtures were labelled GL0, GL20 and GL40. The raw materials and hardened products...

This study aimed to investigate the effect of Titanium Dioxide TiO2 (anatase and rutile) on mechanical and microstructural properties of meta-halloysite based geopolymer mortars namely GMHA and GMHR series. Meta-halloysite received 2.5, 5.0, 7.5 and 10 wt% of anatase or rutile as addition before calcination and geopolymerization. The raw materials...

This paper investigates the use of bauxite widely available in northern Cameroon as an additive in the optimization of some properties of metakaolin-based geopolymer. To do this, several geopolymer mixtures were prepared by substituting metakaolin (MK) by bauxite (BA) (from 0 to 50%) and partially kept at room temperature (28 °C), while others were...

In this paper, four samples of meta-halloysite from widely available Cameroon halloysite clay calcined at 600, 650, 700 and 750 °C, respectively, and the resultant geopolymer binders were systematically characterized. Isothermal conduction calorimetry (ICC) was used to measure the reaction kinetics of meta-halloysite geopolymers at room temperature...

Processing of high calcined grade bauxite and metakaolin-based ceramic by unidirectional humid pressing using five formulation approaches have been studied. They include bauxite with high content of alumina Al2O3 > 86 wt% and metakaolin with silica content SiO2 > 56 wt%; the ceramic products obtained at 1500 °C present 65.9 to 26.8 MPa biaxial bend...

This work aimed to investigate the possibility of using binder obtained from calcined laterite and phosphoric acid as a novel stabilizing for the manufacturing of compressed earth bricks (CEB). Various proportions of binder from up to 20 wt% were used to stabilize the soils. Fourier Transformed Infrared Spectroscopy (FTIR), X-ray diffraction (XRD)...

Limestone was used to modify the fluxing action of two potash feldspars (a pure potash feldspar and a soda-potash feldspar) labeled P and C, respectively, in the formulation of porcelain stoneware based on Cameroonian raw materials. The effect of limestone addition (0–10 mass%) was investigated in the range of sintering temperature between 1125 and...

Microporous porcelain formulations are successfully carried out through sintering processing. During the thermal treatment of ceramic products, it was found that the addition of kyanite together with ϕ- and γ-Al2O3 allowed to enhance interconnected pores network with micrometric size from 0.1 to 9 µm in a semi-vitrifed composite. Between 1200 and 1...

This work reports the mechanical, durability and insulating properties of novel geopolymer composites made of iron-rich laterite and sugarcane bagasse fibers with sodium silicate as a hardener. The results showed that the addition of fibers was beneficial for improving the fracture behavior of iron-rich laterite based geopolymer from brittle to duc...

In this paper, the results of the experimental investigation were used to understand the effect of fine meta-halloysite on the reactivity, mechanical and microstructural properties of laterite-based geopolymers. Laterite was replaced by 0, 20, 30 and 50 wt% of meta-halloysite in order to improve the physico-chemical performance. Meta-halloysite was...

Three porous ceramic composites were prepared from readily available raw materials (kaolin, bauxite, feldspar and kyanite). The porous ceramic formulations were sintered at different temperatures ranging from 1200 to 1400 °C. The fired specimens were characterized by determining their porosity, bulk density, flexural strength, thermochemical stabil...

The crystal structure, the unit cell parameters and the extent of mullitization were determined, using the Rietveld method, for range of mullite matrix formulations in which kyanite is used as particles reinforcement. The results combined with the mechanical properties and microstructure indicated the effectiveness of the kyanite particles to enhan...

Fine particles of kyanite were used as reinforcement in mullite matrix composite. Mix of metakaolin and meta-alumina (calcined bauxite) received different fraction of fine kyanite particles: 37.5, 42.5 and 50 mass%. The objectives were to improve the crystallization of kaolin-based mullite matrix reducing the amorphous content and the grain growth....

Two clayey raw materials from Bamessing (Cameroon) were used to prepare handmade brick samples which were fired under oxidizing conditions (900-1100 °C) to evaluate their possible use in the brick-making industry. The T1 sample is clay-silty-sand and is more plastic than the T2 sample which has a sandy-clay-silty texture. Prepared raw material samp...

Inorganic Polymer Cement paste was used as cleaner binder for the design of lightweight matrices as insulating envelopes and panels in building and construction industries. Sponge like structure with a homogeneously distributed pore network, reduction of the density and important decrease of the thermal conductivity permitted to classify the geopol...