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Physicochemical analysis of different types of clays in analamanga, Itasy and vakinankarata areas

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  • Save International Journal of M aterials and Chemistry 2013, 3(5): 99-105 DOI: 10.5923/j.ijmc.20130305.03 Physico-Chemical Analysis for Differents Types of Clays Soils in the Areas of Analamanga, Itasy and Vakinankaratra Andrianainarive lo Mahandrimanana*, Ranaivoson Jose ph University of Antananarivo, Faculty of Science, Department of Inorganic Chemistry and Physical Chemistry Abstract The aim of this work is to highlight the physicochemical properties of three various types of clay soils respectively collected at Bevalala (sample 1), Arivonimamo (samp le 2) and Antsirabe (sample 3). The analyses obtained by x-ray fluorescence showed the variation of the co mposition of the major elements in each samp le in part icular the rates of SiO2 (47.6%, 41.2%, 52.5%), of A l2O3 (16%, 23%, 25%), of MgO (0.52%, 0.39%, 1.9%) and of Fe2O3 (8.3%, 4.7%, 6.4%) at 500°C.. The study of the plasticity of these samples (Ip1= 29.33, Ip2=14.5, Ip3= 24.16) which are intended for the manufacture of pot, of muds or of bricks allo wed to highlight that the clay soil is more plastic than its plasticity index is important. The addition of Ca CO3 and the heating of the sample at 500°C during five hours make it possible to increase the concentration in CaO. Keywords Clay, X-ray Fluorescence Analysis, Plasticity 1. Introduction In Antananarivo,yellow, gray or white clays, with different thickness, under a weak covering, offer reserves very limited on the industrial sphere because of presence of rice plantations on the surface. Only many artisanal exploitations for brickyard developed, of restricted e xtens ion. These clays, of comp lex co mposition: kaolinite, halloysite (hydrated kaolinite, beidellite, nontronite, cook red. Their reserves (not cubed) appear important but are partly obliterated by the presence of cultures on the surface. An explo itation is designed to feed the cement factory of A n ts irab e. In the coastal area of Madagascar, the soil clays are not useful to build houses because there are a lot of sand. High-plasticity clays occur in many areas of Madagascar especially in the middle and often offer the most economical material alternative for construction of highway embankments. This study shows that in the three areas which we have chosen, the soils contain very important content of clay s . The clays minerals[1] have several physical properties and chemical wh ich are: their faculty to aspire water especially when they dry. They can also reject this water under the * Corresponding author: (Andrianainarivelo Mahandrimanana) Published online at Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved action of heat (phenomenon of hydration and dehydration) [2]. When they are mixed with water, one can obtain fro m it a paste intended for the ceramic manufacturing of product as the bricks and the tiles. The clay fraction is used because its plasticity is easy to calculate by the method of Casagrande. Obtaining a good paste is especially subordinate to this plasticity which depends on the chemical co mposition of clay. Then, we will study the plasticity of the clay soil according to the method of Casagrande. For the chemical properties of the grounds, we will see the chemical composition by the method of spectrometry of Fluorescence to X-rays (FRX). We will approach a part icular study of the clay soils coming fro mthe area of Bevalala, Arivonimamo and the area of the therma l spring of Antsirabe. 2. Theoritical Background In general, the p roperties of the grounds are related to those of the minerals wh ich constitute them. 2.1. Chemical Properties 2.1.1. Structure of the Clay The clay minerals are presented under the aspect of the particles, crystallites or layers of very s mall sizes. 2.1.2. Ionic exchanges Property[3] One of the most known properties of clays is their aptitude 100 Andrianainarivelo M ahandrimanana et al.: Physico-Chemical Analysis for Differents Types of Clays Soils in the Areas of Analamanga, Itasy and Vakinankaratra to fix some an ions and especially the exchangeable cations at other cations and anions. The cations most easily exchangeable in clay materials are: Ca2+, Mg2+, H+, K+, NH4+, NPOa+43a-nadndthNe Oan3i.oOnsnemocasnt eas ily , write exchangeable are for examp le an e : SO42-, Cl-, xchange of the cations: Clay-Ca2+ + 2NaCl Clay - 2Na+ + CaCl2 Here a balance was established but if one systematically renews the solution with balance (by a new solution with balance) by a new solution NaCl, one obtains after several treat ments a clay – Na and the nu mber of equivalence of fixed Na+ is equal to that of moved Ca2+. This balance also depends on the concentrations of the exchangeable ions ( ) Clay ( ) Clay − − Na+ Ca2 2 + = K Na+ 2 Ca2 + With K= the constant of balance If P is the power of absorption one a: P = K Na+     Ca2+ 2  . 1 2    With[Ca2+] and[Na+] are expressed in equivalent grams. During the fixing of the Na+ ions, one can also define solutions used, the capacity of exchange of sodium (sodium adsorption ratio) noted: S.R.A = Na+  Ca2+  + Mg 2+  2 S.A.R is exp ressed in milliequivalents- gram for clay 100g. Values of the capacit ies of exchange of the cations and anions are given in the following table: Table 1. Value of exchange capacity of cations and anions[4] MINERAL Kaolin Halloy sit e Montmorillon it e Hecto rit e Attap ulgit e Illit e Vermiculit e Ch lorit e Sép io lit e Average exchange capacity in (meg) CAT IONS ANIONS 3 à 15 5 à 10 7 à 20 80 à 150 44 23 à 30 20 10 à 40 100 à 150 10 à 40 4 20 à 30 2.1.3. Co llo idal Property of the Clay Matter2 According to the colloidal property of the clay matter, the constituent micelles of a clay paste can slip the ones on the others. This property is supported by the presence of free water in the paste which plays to some extent a part of lubricant allowing the deformat ion and thus returning p las ticity . In a perfectly purified clay i.e. not containing those ions H+ and OH-, we find the colloidal property of clay. Let us suppose that the load of the clay matter is due to the dissociation of clay micelle in micro anion (clay-OH) - and H+ or by adsorption of ions OH- of the aqueous mediu m on the side breaks of the crystal. The positively charged H+ ions revolve around micelles and are attracted by the negative charge of the surface of the core. 2.2. Physical Properties 2.2.1. Plastic Property of Clay The plastic clay soils are very resistant to heat and are composed of fine part icles of kaolin, quartz, illite and mica. One especially emp loys them in the manufacturing of pottery, dishes, tiles for walls, medical parts[5,6] (i.e.bathroo ms). They are also used as agent of filling in rubbers, the plastics, paintings and the adhesives. B.2 Classification of a ground follo wing its degree of plasticity With the index of plasticity, one can classify a soil according to his degree of plasticity. Table 2. degree of soil plasticity Ip 0 à5 5 à 15 15 à 40 > 40 Limit of magnitude: - Clay Ip> 30 - Muddy clay 20< Ip<30 - Silt 10

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