The utilization of silica sand beneficiation cake as a fluxing agent in production of clay brick

The silica sand formations are widespread among Neogene sediments with coal and clay levels around Şile region (İstanbul, Turkey). The silica sand beneficiation cake (SSBC) is formed as a secondary product during the enrichment process of silica sand. The high production of silica sand in the Şile region leads to the generation of large amounts of SSBC. The storage of SSBC and extensive use of fertile alluvial soil in clay brick production cause environmental problems. Our study aims to investigate the use of SSBC as a fluxing agent in brick clay, creating an alternative usage area for SSBC and minimizing environmental problems. The ceramic bricks were produced with 2 different proportions of SSBC (25 and 50%). The mixtures were shaped using extrusion methods and then fired at 700, 800 and 900 °C. The characterisation of raw materials and fired brick samples was carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), differential thermal and thermogravimetric analyses (DTA/TG), X-ray fluorescence (XRF), and physical (particle size distribution, Atterberg limits, shrinkage, weight loss, porosity, bulk density) and compressive strength tests. The addition of SSBC improved the plasticity properties; increased the amorphous phase ratio, firing shrinkage, weight loss, bulk density and compressive strength; and additionally decreased the apparent porosity and water absorption. The improved physical and mechanical properties proved that clay bricks with SSBC can be used in the partition walls in buildings.