Determination of Useful Life of Red Ceramic Parts Incorporated with Ornamental Stone Waste

This study investigated, on a laboratory scale, the effect of the durability of the incorporation of ornamental stone waste in the production of red ceramic parts in order to improve material properties and durability. To reach this objective, ornamental stone waste material, of up to 10% by mass, was introduced to the red ceramic mass. Several other techniques were employed, including X-ray fluorescence chemical analysis, differential thermal analysis, and X-ray diffraction analysis. The samples, pressed to dimensions of $11.0\times 2.5\times 1.0\mathrm{cm}$ with 8% humidity, were oven dried and sintered at 750°C, 850°C, and 950°C and analyzed for water absorption, linear shrinkage, and flexural strength. To predict the strength behavior of the red ceramic parts over time (or over the long term), a low-cost experimental procedure was used to relate the accelerated degradation time in the laboratory for 200 days of saturation and oven-drying cycles at 110°C to the time exposure of the samples to weathering, in this case, for 5 years. The wetting–drying cycles were used to represent the most unfavorable environmental condition for deterioration processes, and the choice of flexural strength over the other properties was due the higher effect of degradation on this property. The useful life of red ceramic parts was defined as when the minimum value of 1.5 MPa was reached, obtaining 14 years for samples sintered at 950°C with stone waste content of 5% by mass and 4.8 years for samples sintered at 950°C with stone waste content of 0% by mass. The durability of red ceramic parts made with stone waste increased 2.91-fold due to the alkali and earth alkali of the stone waste that form molten flux during sintering and the vitreous phase during cooling, closing pores, and thus improving product quality. Furthermore, the stone waste material was inert, leading to proper disposal in the environment.