Industrial Potentiality of Alluvial Clays Deposits from Cameroon: Influence of Lateritic Clayey Admixture for Fired Bricks Production
The cartography and characterization of an alluvial clay deposit from Ebebda (Central region of Cameroon) were carried out in order to assess its suitability for the production of fired clay bricks. The clayey area investigated is ~ 50,000 m2 with an average thickness of the exploitable layer of 2.2 m, suggesting a deposit of about ~2.2 × 105 tonnes of clay. Mineralogy, physico-chemical and thermal analyses as well as firing properties were performed on representative clay samples. Kaolinite and quartz are the major minerals associated to illite. Upon heating to 900℃ - 1200℃, the linear shrinkage varies from 1.5% to 15%, the water absorption from 1.5% to 24% and the bending strength from 2 to 12 MPa. The admixture of lateritic clays (widely available) at 50%, 60%, 70% and 80% allow to decrease the shrinkage and bending strength, and to increase the water absorption. Overall, properties were satisfying the requirement for fired brick with 70% of laterite in the mixture.
Sand size particle amount influence on the full brick quality and technical properties
Abstract In this study was used three different clay types and sand from the local quarry in Latvia. Clay mass mixes were made by adding sand in each mix and remaining the same amount of clay proportion. Sand size particle amount was increased from 33% to 59%. Samples were extruded with laboratory extruded as full brick samples. After formation samples were dried at 105 °C and fired at 1000 °C for 1 h. Water absorption, shrinkage, density, compressive strength were measured after the firing process. The crack amount was determinate by the digital camera after drying process and after firing process. Fired sample cracks start/end points were analysed with SEM-EDX.
Firing transformations of mixtures of clays containing illite, kaolinite and calcium carbonate used by ornamental tile industries
Abstract In this work were studied the firing transformations undergone by mixtures of illitic-kaolinitic clays containing CaCO 3 , free quarts, iron oxides and other impurities, with other kaolinitic and illitic clays also including some impurities but no CaCO 3 . Such mixtures yielded no mullite on heating from room temperature to 950 and 1100°C. This process involves the formation of calcium silicates such as wollastonite in medium to high proportions or calcium aluminosilicates such as gehlenite and anorthitic plagioclases. The proportion in which the last were obtained increased considerably with the firing temperature; on the other hand, the proportion of wollastonite only increased moderately and that of gehlenite decreased with increasing temperature. Some thermodynamic considerations on the formation of these crystalline phases and the absence of mullite were made. Such phases influence the technical properties of the fired products.