Geological and Physicochemical Study of the Alluvial Clay of the Monoun Plain (West Cameroon) As Raw Materials for Ceramic Product

Clay Science 22, 29–37 (2018) –Paper– GEOLOGICAL AND PHYSICOCHEMICAL STUDY OF THE ALLUVIAL CLAY OF THE MONOUN PLAIN (WEST CAMEROON) AS RAW MATERIALS FOR CERAMIC PRODUCT a a, b Isaac Yannick BOMENI , Armand Sylvain Ludovic WOUATONG *, François NGAPGUE , c d Véronique Kamgang KABEYENE , and Nathalie FAGEL a Department of Earth Sciences, University of Dschang, P.O. Box 67 Dschang Cameroon b Department of Civil Engineering, Fotso Victor Institute of Technology, P.O. Box 134 Bandjoun Cameroon c Department of Earth Science, Higher Teacher Training College, P.O Box 47 Yaoundé Cameroon d Department of Geology, University of Liege, 4000, Liege Belgium (Received August 30, 2017. Accepted March 26, 2018) ABSTRACT This study reports the geological and physicochemical characterization of Monoun plain alluvial clays. The field was profiled using an auger corer in three localities (Njimbet, Bangourain, Ngwenfon). The present results reveal good indices of alluvial clay deposits with thicknesses ranging from 0 to 620 centimeters and are made up of various facies. The clay samples were collected from six representative profiles at different localities and they indicated silty clay texture except NJB1_2 and BGR2_2, i.e., a sandy clay texture. In all sample, quartz, kaolinite, goethite, illite and chlorite are the major minerals, while gibbsite, hematite, anatase, and K-feldspar are the minor minerals. Chemical analysis revealed the silico–aluminous character of samples with various iron products (1%<Fe2O3<14%) and small alkali and alkaline earth oxides (0%<Na2O+K2O+CaO+MgO <3%). The physical parameters of alluvial clays exhibit a wide spread granulometry (gravel: 0.0–6.3%; sand: 19.6–79.5%; silt: 12.4–67.4% and clay: 1.5–49.0%) with relatively high plastic index (11–49%). The comparison of Monoun alluvial clay with the others alluvial clays in the country and European clay used in ceramic production indicated similarities in mineralogy, chemical and grain size composition. The reference diagrams of classification of raw clay material for ceramic production also confirm that these alluvial clays can be used in structural ceramics like red stoneware tiles, tiles, roofing tiles, firing bricks and pottery. Key words: alluvial clays, geology, mineralogy, physicochemical, ceramic raw material INTRODUCTION (Künhel, 1990; Murray, 2000). Cameroon products some important clay deposits (Nguetnkam, 2004) all over the country. Clays and clay minerals, the most important materials Since three decades, several investigations on clays and clay used by the manufacturing and environmental industries materials have been performed in different localities (Fig- (Nora, 1999), have been exploited since the Stone Age. ure 1) to obtain the data base for their potential applications. However, an utilization of clay and clay minerals depends For instance, in the central region, alluvial clay from Nanga on their mineralogy, physico-chemical properties and abun- Eboko and Ebebda can be used in firing bricks on an addition dance (Wilson, 2004). Particularly, the clay in SiO2 and of sand to it (Nzeukou et al., 2013). Same characteristics are Al2O3 are used as ceramics (Bagdad et al., 2016; El Yak- also observed on clays from Ngog-Lituba localty (Figure 1), oubi et al., 2006), rubber (Njopwouo, 1984), paint (Zhang i.e., they are suitable for the production of earthenware at et al., 2010), and geochemical barriers (Murray, 2000; Saikia temperatures lower than 950°C (Ndjigui et al., 2016). The et al., 2003). Because of their wide industrial applications, hydromorphic clays from Yaounde area exhibit a high plastic clays are important for the social economic development index which allow their utilization for pottery and brick mak- ing (Ngon Ngon et al., 2009), and the clays from Ozom I are useful for manufacture tiles by adding 47 to 67% of sand and * Corresponding author: Wouatong Armand Sylvain Ludovic, De- flexural agent (Mamba Mpelé, 1993). In the North-West re- partment of Earth Sciences, University of Dschang, P.O. Box 67 gion, Yongue et al. (2016) show that alluvial clays from Ndop Dschang Cameroon. e-mail: [email protected] plain have varied colours like brown, grey and yellowish doi: 10.11362/jcssjclayscience.22.2_29 brown. These clays are able to use for production of roofing 30 I. Y. Bomeni et al. Fig. 1. Map showing areas where alluvial clays have been studied Fig. 2. Geological map of the study area; modified from Dumort in Cameroon. (1968) and Moundi et al. (2007); the black stars indicate the sampling point. tiles, light weight blocks and hollow bricks at a temperature range from 900 to 1100°C. In the North region, the Ngaye GEOGRAPHICAL AND GEOLOGICAL SETTING alluvial clastic clays are useful for the fabrication of bricks (commons and perforated) by an addition of fluxing agent to The study area locates (Figure 2) on the western flank of improve the mechanical performance of the ceramic products Mbam massif (latitude 5°49′ to 6°20′N and longitude 10°36′ (Djenabou et al., 2014). In the Far-North region, alluvial clays to 10 °45′E) and covers a total area of 145 km2. The Mbam from Maroua are used in burnt brick when mixed with other massif is characterized by an elliptical shape with numerous clays, followed by the addition of a flexural agent (Tsozué valleys (Dumort, 1968). It is essentially made of volcanic et al., 2017). In West region, particularly Noun division, al- rocks covering the gneissic basement. The basalt is made luvial clays have been already identified at Marom valley, up of variable proportions of plagioclase, pyroxenes and ac- Njindare valley, Koutaba plain and Monoun plain, respec- cessory opaque minerals (Moundi, 2004). The study area is tively (Nkalih, 2016). In koutaba plain, kaolinite (27–62%) covered by basalt, granite, rhyolite and alluvium from the are major minerals associated with illite (2–13%), smectite weathering of different rocks on the massif. (1–25%) and quartz (11–48%). This mineralogical composition of alluvial clays from Koutaba renders it inappropriate MATERIALS AND METHODS in ceramic products due to the high smectite contents (up to 20%) and some treatments are needed like addition of quartz Alluvial samples or sand before any ceramic application (Nkalih, 2016). So far Seventeen species of alluvial clays were collected from six in, just a superficial investigation was carried out in above representative profiles (0–620 cm) using hand auger corer. mentioned localities. Therefore, the alluvial clays around The corings were made according a 2 km grid in the localities Monoun plain will be specifically subjected to geological of Njimbet, Bangourain and Ngwenfon (Figure 2). Each pro- and physicochemical study to determine its suitability as raw file was described and divided based on texture and colour. A materials for the ceramic industry. The obtained results com- sample was taken in each level of the profile. pared to previous literatures about other alluvial clays along the country and Europe. Mineralogical analysis X-ray diffraction (XRD) was performed for mineralogical analysis. The XRD patterns were obtained by using a Bruker Geological and physicochemical study of the alluvial clay of the monoun plain (west cameroon) as raw materials for ceramic product 31 D8 Advance diffractometer (Department of Geology, AGEs, Physical analysis University of Liege, Belgium) at 40 kV and 25 mA, providing The particle size was determined by wet sieving for frac- a CuKα1 radiation (λ=1.5406 Å). tion ≥80 µm and sedimentry for fraction ≤80 µm according For the analysis of the total disoriented powder, the samples to AFNOR (1992). were first crushed in an agate mortar to obtain particle size Plastic limit was performed on fractions<400 µm. Atter- fraction lower than 150 µm, then dried at 105°C for 24 h. The berg limits was used in order to define the limits of consisten- powder was placed on a sample carrier. The measurements cy between the solid and the plastic state, (plastic limit: WP) were carried out in the 2θ range of 2° to 40° with an angular and the plastic state to the liquid state (liquid limit: WL). The step of 0.01°/s. The relative abundance of minerals has been interval between the plastic limit and liquid limit defines the estimated from the height of diagnostic peak multiplied by plastic index (IP). The plastic limit test was carried out accord- correction factors defined by Cook et al. (1975) and Boski ing to the AFNOR (1993) in the laboratory of MIPROMALO et al. (1998). (Yaoundé-Cameroon). For the analysis of oriented aggregates, samples were placed in solution with water and sieved at 63 µm. The clay fraction RESULTS AND DISCUSSION (< 2 µm) was isolated after a settling time according to Stoke’s law and placed on the slide glass (Moore et al., 1989). Three Description of profiles X-ray patterns were recorded for each sample: air-dried (N), Monoun plain is covered by alluvium and the representa- ethylene-glycol solvated for 24 h (EG), and heated at 500°C tive profiles from Bangourain (BGR1&BGR2), Ngwenfon for 4 h (H). Semi-quantitative estimation of clay minerals was (NGW1 & NGW2) and Njimbet (NJB1 & NJB2) are domi- based on the height of specific reflections measured by the EG nated by silty clay with different colours (Figure 3). condition, multiplied by corrective factors (Thorez, 1976) as Profile BGR1 (E10 °41′40″; N5°52′40″) comprise of five lay- reported in Fagel et al. (2003). ers (Figure 3a). From top to the bottom, the first layer (10 cm) corresponds to the top soil (a1) and contains many rootlets. Infrared analysis The second layer (150 cm) is pale brown (a2: 10YR6/3) The infrared spectroscopy was performed with a resolution with silty clay texture. The third layer (150 cm) is black −1 −1 of 4 cm between 4000 and 400 cm wave number with a (a3: 10YR2/1) and has a silty clay texture.

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