In this work, we studied ettringite formation, C-S-H propagation, and the thermomechanical properties of sugarcane bagasse (SBC) fiber-reinforced concrete with a maximum dosage of 0.17% by weight. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and infrared (IR) analyses were performed. TGA results showed bio-based concrete resistant to temperatures exceeding 500 degree Celsius. TGA results revealed thermal stability of bio-based concrete. SEM analysis showed ettringite and C-S-H propagation without altering mechanical properties. These results are consistent with those obtained by other authors.

This work is a simulation modelling with the LAMMPS calculation code of an electrode based on alkali metals (lithium, sodium and potassium) using the MEAM potential. For different multiplicities, two models were studied; with and without gap. In this work, we present the structural, physical and chemical properties of the lithium, sodium and potassium electrodes. For the structural properties, the cohesive energy and the mesh parameters were calculated, revealing that, whatever the chemical element selected, the compact hexagonal hcp structure is the most stable, followed by the face-centred cubic CFC structure, and finally the BCC structure. The most stable structure is lithium, with a cohesion energy of -6570 eV, and the lowest bcc-hcp transition energy of -0.553 eV/atom, followed by sodium. For physical properties, kinetic and potential energies were calculated for each of the sectioned chemical elements, with lithium achieving the highest value. Finally, for the chemical properties, we studied the diffusion coefficient and the activation energy. Only potassium followed an opposite order to the other two, with the quantities with lacunae being greater than those without lacunae, whatever the multiplicity. The order of magnitude of the diffusion coefficients is given by the relationship DLi > DNa > Dk for the multiplicity 6*6*6, while for the activation energy the order is reversed.

This research work exposes the results of our study about the cartographic and the qualitative estimation of the hydric erosion of the watershed of talangaï (Brazzaville) following the PAP/RAC approach, tele detection's data and the geographical information system in order to elaborate thematic cards by enlightening erosion phenomenon. In this watershed of talangaï, this phenomenon of erosion became recurrent and causes more and more spectacular and worrings. As a matter of fact, except climatic aspects of the study zone, this watershed is characterized by a large irregularity of precipitations, of steep slope, and a weak vegetable coverage; which renders it very vulnerable to the erosion. Thus, after the analysis and the treatment of collected data, from the geographical information system (GIS), the study shows that 65% of zone of study present a weak and average erodibility and 35% of a high and the highest erodibility. Likewise, the descriptive cartography of different forms of erosions shows that ravine surface and the erosion in table-cloth are the most current. Also, the consolidated card of erosion states shows in a qualitative way that soil loss in the zone of study is in relationship with its geomorphology. In short, after combining different cards of principle erosive states, a synthesis has been done producing the consolidated card of these states (Integration approach). All these unfavorable conditions; slopes; geomorphology; erodibility; friability of soils, vegetal covert …), triggering of the catastrophe about erosive phenomenon are fulfilled. Thus, the obtained results allow to identify zones which are the most concerned, and the most vulnerable to hydric erosions.

In this work, the authors made aquatic filters according to the formulation “clay stabilized at 4% of cement mixed with 4% of kambala sawdust and 10% of white sand” then heated to 1050°C to decontaminate the waters of gutters and wells. The authors carried out geotechnical, geochemical, thermal, infrared spectroscopy, and scanning electron microscopy that analyzed the clay material. Geotechnical analyzes have shown that this material is made up of 22% thin sand, 22% of silt, and 56% of clay with 26 plasticity index. The geochemical analysis showed the presence of trace elements shared out as follows: 3% of alkaline metals, 24% of alkaline earth metals, 46% of transition metals, 10% of metal, 16% of lanthanides, 1% of actinides. The most abundant trace elements are barium (19%), vanadium (12%), chromium (11%) and zinc (9%). The thermal and microscopic analyzes revealed the kaolinitic nature of materials. The chemical depollution studies have shown elimination yields of 50% - 52.38% of sulphates; 77.33% - 85.19% of phosphates; 34.85% - 88.49% nitrates; 91.3 - 100 of sulphides; The removal of bacteriological pollution are 92.8% - 98% of total germs; 94% - 97% of total coliform and 95% - 98% of E. coli.

In this study, the authors evaluated the mechanical behavior of bricks made of clay material stabilized with 4% cement and mixed with different contents (0; 2; 4; 6 and 8%) of limba wood waste (sawdust and chips). The clayey raw material ANMK was characterized by the method of X-ray diffraction (XRD) on oriented sheets (normal, glycol and heated to 490°C), by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The chemical and mineralogical compositions of cement used were determined by inductively coupled plasma – optical emission spectrometry (ICP-OES) and by X-ray diffraction. This clay material consists of 96% kaolinite and 4% of the chlorite / montmorillonite interstratified. The morphology of the material observed by scanning electron microscopy showed an irregularity of clusters. The elementary analysis by energy dispersive spectroscopy shows that this material is essentially aluminosilicate. The chemical analysis of the cement showed a predominance of CaO (67%) and SiO2 (21%), however the mineralogical analysis showed the presence of calcite, alite, hatrurite and brownmillerite. This clay material has a mass shrinkage on drying of 26.6% and the linear shrinkage is 6.4%. The formulation with sawdust appears to give greater flexural and compressive strengths than those obtained with chips.

In this work, samples of titanium dental implants in salivary environment in the presence of certain foods were studied. 24 samples were prepared and subjected to the reactivity of certain foods for 6, 5, 6 and 7 weeks. The ICP-MS technique was used to analyze the prepared samples. The results obtained showed no corrosion of the titanium alone in an artificial salivary medium. Significant corrosion was observed in the presence of food, which is manifested by the presence of traces of titanium in the samples.

In the present study, kambala (botanical name: Chlorophora excelsa and Chlorophora regia) wood wastes were incorporated into stabilized earth bricks in order to test their acoustic insulation capacity of the walls; leading to better waste management from the timber industry. Two methods have been applied to determine the influence of the wood waste content in the stabilized earth bricks, on the weakening of the level of noise reception coming from the environmental medium, in an apartment built with composite bricks (earth + wood chips + cement). This influence has also been analyzed on the magnetic field induced by these bricks. The results showed that the level of sound reception through these bricks decreases with increasing wood waste content regardless of the method used (from 110 dB to 68 dB, respectively for Φb = 0% and Φb = 8%). The kambala wood waste in cement-stabilized clay bricks induces a magnetic field that increases with the wood waste content; the high contents of the wood chips causing an increase in the magnetic permeability of the composite medium. The correlation between the noise level and the magnetic field of the bricks shows that the noise level declines with increasing magnetic induction of the bricks.

This study includes the manufacture of cement stabilized clay bricks with embedded mahogany chips.The impact of this waste and its interaction with water in the bricks was evaluated on the mechanical properties.The compressive strength tests using a universal press were carried out on bricks with and without adding wood chips.The results obtained show that the incorporation of wood chips into the bricks decreases the compressive strength.This reduction in compressive strength led us to conduct an analysis of clay and water as intrinsic factors, before and after incorporation of untreated wood waste.Thus, a mineralogical analysis of the clay with and without mahogany chips was made using an X-ray diffractometer, using an anticathode of cobalt with the line Κα, of wavelength λ = 1789Å.After quantification of the mineral

In this paper, we are interested by the dissolution of NAPL (Non-Aqueous Phase Liquid) contaminants in heterogeneous soils or aquifers. The volume averaging technique is applied to 2D systems with Darcy-scale heterogeneities. A large-scale model is derived from a Darcy-scale dissolution model in the case of small and large Damkholer numbers, i.e., for smooth or sharp dissolution fronts. The resulting models in both cases have the mathematical structure of a non-equilibrium dissolution model. It is shown how to calculate the resulting mass exchange and relative permeability terms from the Darcy-scale heterogeneities and other fluid properties. One of the important finding is that the obtained values have a very different behavior compared to the Darcy-scale usual correlations. The large scale correlations are also very different between the two limit cases. The resulting large-scale models are compared favorably to Darcy-scale direct simulations.

The survey of the road construction materials within the Brazzaville Area in the Congo was conducted on the geotechnical data of materials collected from different sites in order to establish a correlation with the norms of their use in Civil Engineering fields. These data include grading curves, consistency limits for the fine fraction, modified Proctor test results and CBR tests. Those data were subjected to classical statistic processing (characterization of every geotechnical parameter variability, study of correlations between parameters). The survey concludes that the material samples analyzed present so close physical properties that they cannot be clearly distinguished through statistical analysis. The overall analysis of the CBR index values varies depending on the materials used. As a consequence these variations cause the deterioration of the pavement structure. The constituents that comply with the above-defined physical properties can be used as materials of a pavement structural layer. The deterioration effects and the granular fragmentation from the Inkisi formations help appreciate the Micro-Deval coefficient and the Los Angeles coefficient, for the figures of both coefficients and result in high figures which means better basic mechanical properties of the foundation and structural layers.

The clay based paint coating was prepared both on a wood and a flat of glass substrates in order to study the adhesion.The scratch test technique associated to the acoustic emission was used to determine adhesion although the critical load which was taken as adhesion measurement.The critical load, mode of coatings removal and acoustic signal are discussed.It is found that the combination of acoustic signal and microscopic observations can indicate whether failure occurs following a cohesive or an adhesive mode.It also found that the critical load is determined by the appears of periodic patterns, this result was found to be in agreement with those obtained by others authors.

The application of engine oils or diesel fuel on the building woods is one of the most commonly used means to control termite invasion in the Congo.Even if this method appears efficient in protecting the wood, it generates a great indoor pollution which has a health impact.Gas chromatography coupled to mass spectroscopy was used in this study to assess the composition of used engine oils and new engine oils.The oils and diesel fuel over time evolution on wood substrate was studied to prevent pollution.The results achieved showed a predominance of hydrocarbon structures which are very toxic to human health, most of which are considered as carcinogenic and even responsible for many respiratory and pulmonary diseases.The study showed that the effect of the pollution depended on how long one stayed indoors and on the nature of the wood.The study also showed that it was better to use diesel fuel in the fight against termites on the wood and that the coatings on the kambala took eleven days and ten on the limba.

An experimental study was carried out on bricks using local materials in order to take into account the waste wood management to protect the environment and to reduce the cost of the habitat. Chips and sawdust were built-in clay bricks in order to study their influence on the compressive strength, Young’s modulus and the speed for soundproofing. Testings in compressive strength were made on the parallelepiped clay bricks, stabilized with different percentages of cement, with incorporation to various percentages of sawdust or wood chips (Mahogany), using a universal press. Young’s modulus was measured from the speed of sound by the ultrasonic method. The results obtained show that the incorporation of mahogany tree chips in the stabilized brick at 8% of cement, does not have much effect on the compressive strength. It was found that the incorporation of chips or sawdust on the clay brick, does not improve the compressive strength. The Young’s modulus decreases with increasing content of sawdust and practically remains constant regardless of the content of chips at 4% and 6% of cement. The clay brick mixed with 8% of mahogany sawdust can be an acoustic barrier.