Low-cost, highly-performance fired clay bodies incorporating natural stone sludge: Microstructure and engineering properties

Abstract

The industry of ornamental stones results in an accumulation of huge amounts in millions of tons of low-cost stone wastes in a very fine state. These stone wastes, particularly granite wastes, are considered a source of feldspar and quartz minerals, that are the essential components for ceramic bodies industry. The current study aims at studying the potential use of granite stone wastes (GSW), as a source of quartz, feldspars, in addition to some clay minerals, in preparing low cost, highly performance fired clay bodies in regard with engineering properties and microstructure investigation. To achieve this goal, the chemical, mineralogical, thermal, and physical characterization of the raw materials using XRF, XRD, TG/DSC, and BET were carried out. Six formulated batches (B0, B1, B2, B3, B4, B5) using different proportions of granite waste (0, 10, 20, 30, 40, 50%) were prepared and fired at different temperatures (1000, 1050, 1100, 1150, 1200, 1250 ºC). The green and fired granite – modified clay bodies were measured for linear shrinkage (DLS, FLS), density, absorption, porosity, compressive strength, and microstructure features (SEM/EDAX). The results showed that the granite wastes are composed mainly of feldspar (albite) and quartz and revealed high percentages of fluxing oxides (CaO, Fe 2 O 3 , Na 2 O, K 2 O). An improvement in the engineering properties of the fired granite - modified clay bodies up to 50% replacement and 1200 ºC firing temperature. The maximum compressive strength and density values were achieved at 40% granite addition for (B4) by 311.92 MPa and 2.48 g/cm 3 ; respectively, with 1.7% water absorption and 8.68% firing linear shrinkage values. The fired clay bodies incorporating granite sludge wastes fulfilled the acceptable ranges for the medium water absorption values (3-10%) as recommended by the international standard (ISO 13006) for use as ceramic tiles. • Manufacturing of low- cost fired clay bodies using granite sludge wastes. • An observable reduction in drying linear shrinkage up to 50% granite sludge wastes • A remarkable enhancement in engineering properties using up to 50% granite sludge wastes replacement. • A significant reduction in the firing linear shrinkage up to 50% wastes addition and 1200 ºC firing temperature • A remarkable increase in compressive strength up to 1200 ºC firing temperature and 40% waste addition