Two clays named DAB1 and DAB2 were collected in the town of Dabou. The samples came from the village of Youhouill in the Grand Pont region of southern Côte d’Ivoire. The clay sampling site is located at geographic coordinates 05˚21'29''N and 04˚3'18''W.

We collected clay samples on site using a hoe. We placed the samples in 25 kg nylon bags. We then transported them to the laboratory. For each sample, we took 5 bags of 25 kg from each site.

Before characterization, we dried samples in the shade for three days. We crushed, crumbled, washed and dried the clay blocks. We ground a portion of each sample in a glass mortar. We sieved the powder through a 100 μm sieve to obtain a homogeneous powder for analysis.

We weighed 2g of clay and ground it in an agate mortar. We sieved the rock powder through a 63µm sieve. We placed the collected powder in the sample holder and compacted it with a glass plate. We then analyzed it by XRD. The analysis parameters were 28 mA current, 20 kV voltage, 1 kW power and 4.5 mA filament amperage. The monochromatic radiation for the measurements was the copper Kα line (λ = 1.5406 Å). The sample holder was tilted at an angle of 4˚. We performed phase identification with Match software. We used the GBC-EMMA diffractometer for X-ray diffraction.

We determined the chemical composition of the clays by ICP-AES and EDS X-ray mapping. We carried out chemical analysis by ICP-AES with an ANTON Paar spectrometer. Before measurement, we put samples into a solution using a microwave-assisted chemical process. The procedure involved several steps. We introduced 30 mg of each sample with a particle size of 100 µm or less into a Teflon tube. We had previously dried the samples at 110˚C for 24 hours. We added 4 mL HF (28 vol%) and 1 mL HNO₃ (68 vol%) to the tube. We placed the assembly into a microwave device (CEM, MARS 5) and subjected it to a 45-minute cycle. Dissolution took place during a 20-minute rise in temperature (Tmax = 180˚C) and pressure (pressure reached = 3 MPa). This was followed by a 20-minute plateau at 180˚C. We then cooled the sample to room temperature. After dissolution, we made up the volume to 250 ml in a volumetric flask for analysis. We acquired X-ray mapping over the entire sample surface with an X FLASH 6/30 EDS spectrometer. We suspended a small mass of the sample in ethanol and ultrasonicated it for five minutes. We then pipetted a drop onto a polished sample holder. We placed the sample holder in a box and dried it in ambient laboratory air. Finally, we put it under the microscope for energy dispersive analysis.

We carried out granulometric analysis on dried clay samples with laser granulometry. We used PARTICA HORIBA equipment for this analysis. We performed granular analysis by sedimentation on dried clay samples that were crushed and sieved to 100 µm. We conducted particle size analysis by sieving and sedimentometry according to standards NF P18-560 [7] and NF P94-057 [8] respectively. We determined the liquidity limit (WL) using the Casagrande disk method. We determined the plasticity limit (WP) using the roller method. We determined these Atterberg limits according to standard NF P94-051 [9] .

We reported elsewhere [10] that x-ray diffraction analysis revealed the composition of the DAB1 and DAB2 clay samples. These samples consist mainly of kaolinite, goethite, illite and quartz [10] . [15] 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 to analyze the clay material. Also, some researchers [16] - [23] have used clays in industrial fields (brick making, environment). The authors obtained characterization results similar to ours.

We carried out chemical analysis on samples DAB1 and DAB2. The results show significant quantities of silica SiO₂ at 67.54% for DAB1 and 58.21% for DAB2. Alumina Al₂O₃ content reached 21.87% for DAB1 and 28.11% for DAB2. Sample DAB1 contains more silica than sample DAB2. However, DAB1 contains less alumina Al₂O₃, iron oxide Fe₂O₃, potassium oxide K₂O and titanium oxide TiO₂ than sample DAB2. The Fe₂O₃ iron oxide content is relatively high in both samples. K₂O, Na₂O and TiO₂ oxides appear in small quantities [10] . Chemical analyses revealed high levels of silica (SiO₂: 58% - 68%) and alumina (Al₂O₃: 21% - 29%). These levels characterize alumino-silicate clays. Iron (Fe₂O₃: 8% - 12%) is also present. We calculated the Al₂O₃/Fe₂O₃ ratio as 2.44 for DAB1 and 2.43 for DAB2. Both ratios fall below 5.5. These samples are therefore rich in iron. They can be manufactured into building materials such as bricks and tiles [16] - [18] [24] . ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) offers a more precise and quantitative assessment of elemental compositions compared to EDS (Energy Dispersive X-ray Spectroscopy), which provides semi-quantitative results.

Figure 1 shows chemical mapping of sample DAB1. Technical limitations prevented us from conducting chemical mapping of sample DAB2. Aluminum and Oxygen distribute homogeneously throughout the sample. Carbon, Silicon, Iron and Titanium concentrate in specific areas while maintaining equal distribution throughout the sample. These chemical elements are therefore superimposable. Carbon (in red) originates from organic matter present in the soil’s natural environment. This analysis did not identify Potassium and sodium. The chemical mapping study reveals that DAB1 clay consists essentially of C, O, Al, Si, Fe and Ti. This composition aligns with the different phases detected during mineralogical characterization of these clays. The phases include Si₂O₅Al₂(OH)₄ for kaolinite, FeO(OH) for goethite and SiO₂ for quartz.

EDS analysis is a semi-quantitative analysis. EDS analysis allows the identification and quantification of the elements present, as well as the visualization of their spatial distribution within the sample by detecting the X-rays emitted when it is bombarded by an electron beam. Figure 2 and Figure 3 show the EDS spectra of samples DAB1 and DAB2. This analysis did not identify potassium and sodium. However, ICP-AES chemical composition analysis identified these two chemical elements in oxide formation at low percentage rates. The silica and alumina contents indicate that these two samples are aluminosilicates. The iron content could induce the production of hydroxyl radicals via the Fenton reaction. The low potassium oxide content could suggest the presence of illite and muscovite. Carbon relates to contamination and originates from organic matter present in the clay’s natural environment. The presence and concentration of oxygen may indicate formation of various oxides or oxygenated compounds. These compounds are essential for understanding the material’s properties. High oxygen levels in geological studies can indicate weathering processes. These processes transform primary minerals into more oxygen-rich secondary minerals such as clays. The much higher iron levels in these samples are responsible for their brick-red color. This vibrant hue is a real advantage, as it can be used as a natural colorant for clay bricks and tiles [18] [24] . Iron in clay raw materials can be “structural”, i.e., it replaces Si⁴⁺ or Al³⁺ cations in tetrahedral and/or octahedral layers. It can also be “non-structural”, occurring as individual particles such as oxyhydroxides, e.g, goethite (α-FeOOH) and lepidocrocite (γ-FeOOH), or as oxides such as hematite (α-Fe₂O₃) and maghemite (γ-Fe₂O₃) [25] [26] .

We present microanalysis of samples DAB1 and DAB2 by EDS (mass%) in Table 1 . Quantification by microanalysis shows the composition of both samples. Sample DAB1 contains 11.92% carbon (C), 49.41% oxygen (O), 12.93% aluminum (Al), 15.74% silica (Si), 0.84% titanium (Ti) and 9.22% iron (Fe). Sample DAB2 contains 11.33% carbon (C), 78.96% oxygen (O), 12.42% aluminum (Al), 14.74% silica (Si), 0.79% titanium (Ti) and 7.65% iron (Fe). These results are similar to those of other authors with different composition percentages [27] - [29] .

Laser diffraction and sedimentation (sedimentometry) are two widely employed methods for analyzing particle size distributions in materials such as soils, clays, and suspensions. Despite their common application, these techniques rely on distinct physical principles, which can occasionally produce discrepant or complementary results in the characterization process. Granulometric analysis was performed through sedimentation on dried, crushed, and 100 μm-sieved clay samples. Particles exceeding 2 mm in diameter were removed using a 2 mm (10 mesh sieve). The sieved material was homogenized, and approximately 40 g of the dried sample was dispersed in water containing a dispersing agent before being transferred into a graduated cylinder. The mixture’s density was then measured at various time intervals, ranging from 30 seconds to 24 hours, using an oedometer. Monitoring the variation in density over sedimentation time enabled the determination of the particle size distribution within the sample. Prior to detailed characterization, the samples were sieved with a 100 μm mesh. Traditionally, sieving is used to separate coarse particles larger than 40 μm, while laser diffraction techniques are typically applied to analyze finer powders in the micrometer range. Particle size distribution is derived from the interaction between incident radiation and individual particles, allowing for accurate measurement of grain sizes spanning from a few micrometers up to several millimeters in particulate samples. The results of the laser diffraction particle size analysis are presented in Table 2 . The various mean diameters, namely d₁₀, d₅₀, and d₉₀-correspond to the particle volumes below which 10%, 50%, and 90% of the total volume are contained, respectively. These data indicate that the DAB1 clay exhibits a finer particle size distribution compared to DAB2. The higher values of d50 and d90 observed in DAB2 suggest the presence of significant particle agglomeration, likely resulting from inadequate dispersion of the suspension [30] .

Table 3 presents the sedimentometric particle size distribution for the clay samples DAB1 and DAB2. The analysis indicates that DAB1 comprises approximately 47.8% silt and 52.2% clay, while DAB2 consists of about 47.5% silt and 52.5% clay. These results demonstrate that both samples have comparable proportions of silt and clay fractions.

Atterberg limits are fundamental parameters used to characterize the consistency and plasticity of fine-grained soils, with their values being influenced by particle size distribution and mineralogical composition. Determining these limits is a standard method for evaluating the mechanical behavior of clays [31] , as they reflect changes in soil behavior relative to water content. The liquid limit (W_L) marks the transition of a soil from a plastic to a liquid state, indicating the minimum water content at which the soil becomes flowable. Conversely, the plastic limit (W_P) defines the boundary between plastic and solid states and corresponds to the maximum water content at which the soil can be deformed without crumbling. The difference between these two limits, known as the plasticity index (I_P), provides valuable insights into soil plasticity. For the samples studied, the plasticity indices were 37 for DAB1 and 30 for DAB2. According to [32] , soils with I_P values between 20 and 40 are classified as plastic, indicating that both DAB1 and DAB2 are indeed plastic clays. We present these results in Table 4 . The W_L liquidity limit values are 72% for sample DAB1 and 58% for sample DAB2. Samples DAB1 and DAB2 show W_P plasticity limits of 35% for DAB1 and 28% for DAB2. The plasticity index values are 37 for DAB1 and 30 for DAB2. The consistency index Ic shows little variation. The value for DAB2 (1.99) is higher than that for DAB1 (1.88). The average Ic of 1.93 for both clay samples is greater than 1.

The specific surface area expressed (m² g⁻¹) represents the total surface area of particles per unit mass. It is highly dependent on particle size. Density depends on particle arrangement and porosity. Porosity is the ratio of void volume to total soil volume. It is directly dependent on particle size distribution. The specific surface area, density, and porosity values for samples DAB1 and DAB2 are shown in Table 5 .