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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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作者 Nice Mfoutou Ngouallat Narcisse Malanda +3 位作者 Christ Ariel Ceti Malanda Kris Berjovie Maniongui Erman Eloge Nzaba Madila paul louzolo-kimbembe 《Geomaterials》 2024年第2期13-28,共16页
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... 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. 展开更多
关键词 Statistical Thickness Model External Specific Surface Microporous Surface Clay Concrete MOLASSES
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Concrete Formulation Study for Informal and Semi-Informal Construction Sectors
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作者 Narcisse Malanda paul louzolo-kimbembe +2 位作者 Louis Ahouet Jarlon Brunel Makela Guy-Richard Mouengue 《Open Journal of Civil Engineering》 2019年第1期57-79,共23页
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 an... 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. 展开更多
关键词 FORMULATION CONCRETES AGGREGATES Cement Physico-Mechanical Characteristics INFORMAL and Semi-Formal SECTORS
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Survey on Storage of Water for Domestic Use in Underground Reinforced Concrete Tanks: The Case of Brazzaville (Republic of Congo)
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作者 Narcisse Malanda paul louzolo-kimbembe 《Open Journal of Civil Engineering》 2014年第1期13-22,共10页
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 reinforc... 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. 展开更多
关键词 UNDERGROUND Tanks Watertightness Reinforced Concrete WATER STORAGE Potability Household
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Influence of Aggregate Grain Size on the Formulation of Sand Concrete in the Construction Industry in Congo
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作者 Charlène Bassolokidi Nkengue Narcisse Malanda +2 位作者 Gilbert Ganga paul louzolo-kimbembe Guy Richard Mouengue 《Geomaterials》 2019年第4期81-96,共16页
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 characte... 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. 展开更多
关键词 SAND FORMULATION RECOVERY Materials SAND CONCRETE Physico-Mechanical Characteristics Construction
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Adsorption Isotherm of BET Nitrogen of Concretes with Consolidated Soil by Sugar Cane Molasses
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作者 Nice Ngouallat Mfoutou Narcisse Malanda +1 位作者 Erman Eloge Nzaba Madila paul louzolo-kimbembe 《材料科学与工程(中英文B版)》 2022年第3期78-96,共19页
Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the dust.Nitrogen physical adsorption has allowed us to collect information on the state of the acce... Sugar cane molasses is often poured out on roads with soil in the city of Nkayi,Republic of Congo in order to reduce the dust.Nitrogen physical adsorption has allowed us to collect information on the state of the accessible total area according to the quantity of sugar cane molasses.The 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 examined.The 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 materials.Materials with elaborated raw soil by clayey fine soil used are mesoporous materials.More of 50×1018 molecules constituting sugar cane molasses occupy the extreme area accessible to soil clay,without occupying on accessible sites. 展开更多
关键词 ISOTHERM adsorption BET(Brunauer Emmet and Teller)specific area clayey fine soil sugar cane molasses
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Microstructure of Fine Clay Soils Stabilized with Sugarcane Molasses
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作者 Narcisse Malanda Nice Ngouallat Mfoutou +1 位作者 Erman Eloge Nzaba Madila paul louzolo-kimbembe 《Open Journal of Civil Engineering》 2022年第2期247-269,共23页
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 re... 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. 展开更多
关键词 MICROSTRUCTURE Consolidated Clayey Fine Soil Molasses of Sugar Cane MESOPORE MICROPORE Specific Surface Area
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