Characterization and application tests of kaolinite clays from Aboudeia (southeastern Chad) in fired bricks making

Abstract

In this study the characterization and application tests for fired bricks manufacturing of kaolinite clays from Aboudeia (southeastern Chad) are reported. Grain size distribution, X-ray diffraction (XRD), Fourier transform infra-red (FT-IR), chemical analysis using X-ray Fluorescence (XRF), and thermal analysis (TGA-DSC) were used to characterize the raw clays samples. Fired products at 900, 1000 and 1100 °C were analyzed using Scanning Electron Microscope (SEM), and physical and mechanical tests (including shrinkage, flexural strength, water absorption, and porosity). The investigated materials are kaolinite-based clays with low alkali content. Their textural analyses, which included particle size distribution, liquid limit and plasticity index, indicate that the Aboudeia clays can be used for dense bricks, hollow bricks and vertically perforate bricks. However the technological properties, in particular the water absorption suggest that, for proper used of this clay for structural bricks, fluxes amendment is needed. The fired products are in general colored pinkish to pinkish white, for two of the samples (A1 and A2), because of their relatively low goethite content. While for the other the brown to red color due to the goethite conversion in hematite, is dominant. The fired products exhibit relatively low flexural strength and high water absorption. Keywords: Flexural strength, Thermal analysis, Mineralogy, Water absorption