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Open Journal of Civil Engineering 2014年第1期4卷 13-22页

作者： Narcisse Malanda paul louzolo-kimbembe Laboratory of Civil Engineering and Environmental Engineering National School of Engineering University Marien Ngouabi Brazzaville Congo

The problem of water supply from the public distribution network still poses very serious problems in many cities in developing countries. Intermittent water supply pushes some households to build underground reinforced concrete tanks for water storage to cope with unwanted water breaks. This study that relies on the results of a survey of households in some areas of the city of Brazzaville (Republic of Congo) aims to verify the importance that users attach to the quality of the works constructed. Indeed, the reliability of the tanks resulting in their impermeability to the external environment has a direct impact on the quality of stored water and therefore the use that is made of water daily. Five areas were selected because of their soil moisture. By 256 tanks identified, 143 are made of reinforced concrete and 113 in masonry. The coating materials used to seal the walls are preferably the earthenware tiles (64% of tanks), then the Sika cement (31%). Food painting (5%) is only rarely used. However, 66% of households are not assured of the potability of the water stored. A significant number of households (46%) think that the stored water could be contaminated with noxious substances seeping from the outside through the walls of the tanks. The issue of sealing of underground water tanks, especially in areas where the water table is shallow, seems concerned users.

关键词： Underground Tanks Watertightness Reinforced Concrete Water Storage Potability Household

Microstructure of Fine Clay Soils Stabilized with Sugarcane Molasses

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Open Journal of Civil Engineering 2022年第2期12卷 247-269页

作者： Narcisse Malanda Nice Ngouallat Mfoutou Erman Eloge Nzaba Madila paul louzolo-kimbembe National Upper Polytechnic School Marien Ngouabi University Brazzaville Republic of Congo Department of Chemistry Biochemistry and Physics and Hydrogen Research Institute University of Quebec in Trois-Rivières Trois-Rivières Canada National Upper Education School Marien Ngouabi University Brazzaville Republic of Congo

Sugar cane molasses has proved cohesive and excellent performance on soil aggregates (fine particles). However, the microstructure of consolidated soil by the molasses is not yet subjected to research. The analysis results of sample without molasses (0%) and consolidated samples at 8%, 12%, and 16% show that the molasses acts on the structure of clayey fine soil developing its microstructure of airy matrix type (sample without molasses (0%) to a microstructure of a qualified type, more solid. Consolidated samples to 8%, 12%, 16% of molasses). We also observe the presence of inter-aggregate pores (mesopores) of similar size in all samples. The results of porosimetrical analyses (BJH) of the sample without molasses and consolidated samples to 8%, 12%, and 16% show that simultaneous porous volumes of samples are reduced with the increasing of molasses quantity. This latter, therefore, acts on the porous volume (micropore 2 nm and mesopore 9 nm) by reducing them which really means, molasses occupies the porous volume of the sample. However, this sample seems not to have any effect on the size of mesopores 9 nm. Thus, this product induces the evolution of the soil structure towards the highly dense and condensed structure. Consequently, materials in consolidated soil by molasses will have mechanical properties far superior to those of materials consolidated soil without molasses.

关键词： Microstructure Consolidated Clayey Fine Soil Molasses of Sugar Cane Mesopore Micropore Specific Surface Area

Adsorption Isotherm of BET Nitrogen of Concretes with Consolidated Soil by Sugar Cane Molasses

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材料科学与工程（中英文B版） 2022年第3期12卷 78-96页

作者： Nice Ngouallat Mfoutou Narcisse Malanda Erman Eloge Nzaba Madila paul louzolo-kimbembe National Upper Polytechnic School Marien Ngouabi UniversityBrazzaville BP.69Congo Department of Chemistry Biochemistry and Physics and Hydrogen Research InstituteUniversity of QuebecTrois-RivièresQuébecG9A5H7Canada Upper School of Education Marien Ngouabi UniversityBrazzaville BP.69Congo

Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the *** physical adsorption has allowed us to collect information on the state of the accessible total area according to the quantity of sugar cane *** adsorption isotherms,the specific area,the adsorbed quantity of nitrogen on a Qm mono layer,the number of molecules constituting the adsorbed sugar cane molasses(n′)have been *** obtained results show that the quantity of sugar cane molasses in the material does not modify the adsorption isotherm of nitrogen of type IV that remains and a hysteria loop of type H4 in all samples,this justifies the monocoat-multicoat adsorption mechanism with capillary condensation and mesopores presence in the structure of *** with elaborated raw soil by clayey fine soil used are mesoporous *** of 50×1018 molecules constituting sugar cane molasses occupy the extreme area accessible to soil clay,without occupying on accessible sites.

关键词： Isotherm adsorption BET(Brunauer Emmet and Teller)specific area clayey fine soil sugar cane molasses

Concrete Formulation Study for Informal and Semi-Informal Construction Sectors

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Open Journal of Civil Engineering 2019年第1期9卷 57-79页

作者： Narcisse Malanda paul louzolo-kimbembe Louis Ahouet Jarlon Brunel Makela Guy-Richard Mouengue National Polytechnic High School Marien Ngouabi University Brazzaville Congo Normal High School Marien Ngouabi University Brazzaville Congo Building and Public Works Control Office Brazzaville Congo

The present work consisted in carrying out a study on the effective formulation of concrete for an optimal resistance to compression (fc28) between 20 and 30 MPa for the sites animated by the actors of the informal and semi-informal sectors of the construction. Studies have been carried out on projects under construction, by taking samples of fresh concrete in order to evaluate their real compressive strengths. These surveys show that there is a problem in the concrete formulation, as nearly 2/3 of the results show the lack of technical knowledge on concrete formulation practices. Indeed, on eight sites surveyed and whose fresh concrete samples were taken, only two sites (7 and 8) report fairly consistent results. Their 28-day compressive strength values are respectively 35.36 and 22.18 MPa. In addition, various formulations proposed with aggregates from different quarries or extracts from the bed of the Congo River, were determined in the laboratory. This study allowed us to obtain fairly objective results overall, which is characteristic of concretes of required quality. Of the six (06) formulation proposals, average resistances of 19.6 MPa at 07 days and 25.28 MPa at 28 days were obtained. These results at 28 days are in the range of 20 to 30 MPa, set as objective in this study. These formulations can be a reliable source for concrete manufacturers in these construction sectors. Similarly, the statistical study based on principal component factor analysis tests has shown that the most appropriate formulation, in terms of mechanical resistance, is that proposed with sand extracted from the Congo River (formulation 3). This is justified by the fact that this sand is consistent and has a good granular distribution.

关键词： Formulation Concretes Aggregates Cement Physico-Mechanical Characteristics Informal and Semi-Formal Sectors

Influence of Aggregate Grain Size on the Formulation of Sand Concrete in the Construction Industry in Congo

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Geomaterials 2019年第4期9卷 81-96页

作者： Charlène Bassolokidi Nkengue Narcisse Malanda Gilbert Ganga paul louzolo-kimbembe Guy Richard Mouengue National Higher Polytechnic School Marien Ngouabi University Brazzaville Congo Office of Control of Buildings and Public Works Brazzaville Congo

The main objective of this study is to contribute to the optimization of the formulation of sand concretes and its valorisation according to natural sands from different quarries or extraction sites. Physical characteristics of natural sands have been determined and improved by the addition of crushing sand, taking into account the too fine elements of the sand. Four types of sand were used (Congo River, Djiri, Mfilou, crushed sand). The concrete formulations proposed from improved sands (30% crushed sand and 70% natural sand) reveal an increase in mechanical strength. Thus, it appeared that this improvement of the natural fine sands by the crushing sand has brought a clear increase in the maneuverability of the concretes and the physico-mechanical characteristics of nearly 50%, although this crushing sand has a sand equivalent value of less than 70%. These results augur well for the durability of structures in the construction industry in Congo.

关键词： Sand Formulation Recovery Materials Sand Concrete Physico-Mechanical Characteristics Construction

Improvement of the Geotechnical Properties of the Soil of Lime-Treated Cubitermes Mound Soil

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Open Journal of Civil Engineering 2020年第1期10卷 22-31页

作者： Séverin Jean Maixent Loubouth Louis Ahouet Raymond Gentil Elenga Sylvain Ndinga Okina paul louzolo kimbembe Laboratoire des Matériaux et Energies Faculté des Sciences et Techniques Université Marien Ngouabi Brazzaville Congo Ecole Nationale Supérieure Polytechnique Université Marien Ngouabi Brazzaville Congo Bureau de Contr?le du Batiment et Travaux Publics Brazzaville Congo Ecole Normale Supérieure Université Marien Ngouabi Brazzaville Congo

This work consisted in determining the geotechnical properties of the soil of the Cubitermes termite mound soil treated with lime for use in road construction in accordance with the relevant standards. The raw soil is composed of 29.45% clay, 45.12% silt and 25.43% sand, and its granulometric curve is above the relevant standard curve. The addition of lime up to 9% decreases the fine fraction content from 75% to 60%, and the maximum dry density from 1.62 t/m3 to 1.36 t/m3. The reduction of the fine fraction should reduce the soil sensitivity to water, and the emission of dust from the road. The compressive strength of the raw soil (3.89 MPa) is higher than that of most cohesive soil, and is probably one the causes of the longevity of the rural road paved with this soil. Treated soil with 6% in lime content has the highest compressive strength (5.95 MPa), and the lowest deformation at failure. Until 28 days, the improvement of the compressive upon the curing time is almost the same for untreated and treated termite mound soils. Thus, this improvement could be mostly attributed to the drying of the samples instead to the pozzolanic reactions. Besides, adding lime also enhances the shear strength of soil. Therefore, adding lime up to 6% in content to the termite mound soil should improve its behavior as surface roads.

关键词： Cubitermes Mound Soil CEBTP 1980 Unpaved Roads Geotechnical Properties

Comparative Analysis of Statistical Thickness Models for the Determination of the External Specific Surface and the Surface of the Micropores of Materials: The Case of a Clay Concrete Stabilized Using Sugar Cane Molasses

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Geomaterials 2024年第2期14卷 13-28页

作者： Nice Mfoutou Ngouallat Narcisse Malanda Christ Ariel Ceti Malanda Kris Berjovie Maniongui Erman Eloge Nzaba Madila paul louzolo-kimbembe Mechanics Energy and Engineering Laboratory Higher National Polytechnic School Marien Ngouabi University Brazzaville Republic of the Congo National Institute for Research in Engineering Sciences Innovation and Technology (INRSIIT) Brazzaville Republic of the Congo Higher Institute of Architecture Building Planning and Public Works Denis SASSOU N&#8217GUESSO University Kint&#233l&#233 Republic of the Congo Hydrogen Research Institute University of Quebec in Trois Rivieres Quebec Canada Superior Normal School (ENS) Marien Ngouabi University Brazzaville Republic of the Congo

In this work, four empirical models of statistical thickness, namely the models of Harkins and Jura, Hasley, Carbon Black and Jaroniec, were compared in order to determine the textural properties (external surface and surface of micropores) of a clay concrete without molasses and clay concretes stabilized with 8%, 12% and 16% molasses. The results obtained show that Hasley’s model can be used to obtain the external surfaces. However, it does not allow the surface of the micropores to be obtained, and is not suitable for the case of simple clay concrete (without molasses) and for clay concretes stabilized with molasses. The Carbon Black, Jaroniec and Harkins and Jura models can be used for clay concrete and stabilized clay concrete. However, the Carbon Black model is the most relevant for clay concrete and the Harkins and Jura model is for molasses-stabilized clay concrete. These last two models augur well for future research.

关键词： Statistical Thickness Model External Specific Surface Microporous Surface Clay Concrete Molasses

Thermo-Mechanical Properties Study of Stabilized Soil Bricks to Sugar Cane Molasses and Cassava Starch Binders

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Open Journal of Applied Sciences 2023年第2期13卷 240-260页

作者： Narcisse Malanda Jean Albin Nkaya Gilbert Ganga Ngambara Emamou Nondel Durvy paul louzolo-Kimbémbé Polytechnic National Superior School (ENSP) Marien Ngouabi University Brazzaville Republic of the Congo Superior Normal School (ENS) Marien Ngouabi University Brazzaville Republic of the Congo National Institute for Research in Engineering Sciences Innovation and Technology (INRSIIT) Brazzaville Republic of the Congo

The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been suggested after the geotechnical characterization of samples of soil was taken. From these, it arises that the studied soil is the most plastically clay (of type A3) according to GTR classification. Samples made of small bricks and measured out at 4%, 6% and 8% of binders (molasses, starch or molasses + starch) have been warmed up to different temperatures (100°C, 150°C, 200°C and 250°C) for the rising of the thermic behavior under different conditions and submitted to crushing testings for the estimation of characteristic resistances to the compression. According to the mechanical behavior, we note an improvement of resistances for small bricks measured 4%, 6% and 8%, of molasses respectively of 32.44%, 32.06% and 23.43% against the value of reference for small bricks without molasses. In the same way, the binder (molasses + starch) also reveals an improvement of resistance to the compression of 13.27%, 26.17% and 26.17%. On the contrary, the stabilization with the starch binder did not bring a significative improvement. According to the thermic influence, the heating at 100°C of stabilized small bricks at 4%, 6% and 8% of molasses, reveals a significative improvement of resistances. Moreover, the stabilization with the starch reveals on the contrary a good behavior for heatings at 150°C and 250°C. In short, for the binder (molasses + starch), it is the heating at 200°C that shows some improvements of remarkable resistances. Different analyses of realized statistics also show the effectivity of obtained results. For all realized formulations, the measuring out at 6% of binders (molasses, or molasses + starch) seems as optimal in front of the best thermo-mechanical revealed properties.

关键词： Clay Molasses Cassava Starch Heating Compressed Soil Brick Mechanical Resistance