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Ceramic materials such as bricks and tiles used in civil construction, may eventually be exposed to weather conditions and undergo degradation with time. Although this degradation has been studied in common plain ceramics, it has not yet been investigated in clay ceramics incorporated with ornamental stone residues. In the present work the degradation suffered by clay ceramics incorporated with 5 and 10 wt % of a granite residue under weathering for 6, 8 and 10 months was evaluated. The incorporated and plain ceramics were fired at temperatures of 500, 700 and 900°C. The linear dimensional changes were measured just after firing as well as after 180, 240 and 300 days, respectively, 6, 8 and 10 months. In general, the linear dimensions tend to increase with time and firing temperature. The role of absorbed water on these changes is discussed.

In recent decade there has been a worldwide trend towards encouraging the recycling of solid wastes. Both environmental and economical issues motivate recycling of industrial wastes from practically all productive sectors. In particular, the ornamental stone industry generates a significant amount of wastes in the form of small rocks and sludge. Several works have investigated the possibility of incorporation of these ornamental stone wastes (OSW) into red clay ceramics. Promising results were reported but the optimum condition the terms of composition and firing temperature are still to be defined. Therefore, the present work investigated the best values for the main technical properties through an experimental planning using 32 factorial design associated with the incorporation of OSW into clay ceramics. The best combination of strength and water absorption was found for 12 wt% incorporation and firing temperature of 920°C.

From the point of view of mechanical strength, ceramic materials exhibit dispersion results after being subjected to various levels of stress. However, there are no statistical surveys addressing the results efficiently. The present study aims to conduct with statistically survey, through the Minimum Lot Size, Chauvenet criterion and the Tukey range test. Specifically, the mechanical strength of red ceramic incorporated with ornamental rock waste and fired up to 700°C was analyzed, before and after degradation. The pieces were subjected to degradation of up to 1,500 hours by continuous leaching and of up to 10 months by the natural process. The results of the Tukey Test, before and after the degradation, showed statistical differences, ensuring that the data analysis was effective.