Bulletin of the Mineral Research and Exploration (Dec 2022)
Investigation of thermal transformation of composite material obtained from granite and recrystallized limestone natural stone wastes
Abstract
In this study, the usability of granite (magmatic) and recrystallized limestone (metamorphic) natural stone wastes as alternative raw materials in ceramic tile production was investigated. Based on the CaO, SiO2, and Al2O3 compounds found in waste powders, mixtures containing 65% granite and 35% recrystallized limestone (by mass) were prepared to obtain the ceramic phases of gehlenite, wollastonite and anorthite as a result of thermal transformation. The grain size of both raw materials is -149 μm (d90 = 110.957 μm). The powder mixtures were moistened with 7% (by mass) water and shaped in a steel mold with dimensions of 75x20x50 mm with a uniaxial press with a setting of 127 MPa. The first series samples were called as natural building stone (DYT), and the second series samples, in which wood chips of 2% (by mass) -1 mm grain size are added to obtain porous material, were called as natural building stone - porous (DYT-G). The samples belonging to both series was applied heat treatment at 1.160°C. Phase analysis of samples obtained after heat treatment was measured by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM-EDS) methods, and sintering properties were measured using water absorption coefficient, flexural strength, modulus of elasticity, density-porosity and color measurement tests. Gehlenite and wollastonite phases were detected in the heat treated samples, but no anorthite phase was observed. According to the test results, it was determined that the flexural strength (22.64 MPa) of the DYT marked sample was in accordance with the ceramic tile standards. In the DYT-G example, despite the decreasing unit volume mass value, it was determined that the bending strength (16.50 MPa) was in the rangeof ceramic tile strength values.
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