Effects of High Temperatures on Concrete with Recycled Aggregates from Ceramic Stoneware Waste

Abstract

The Spanish ceramic tiles industry is a major player on the market, with an annual production of 587 million m2, that generates around 4,855 million euro. Most of this production (94%) is concentrated geographically in a cluster in the province of Castellón (Spain). However, it is estimated that around 1.5–2% of the ceramic products contain defects or cracks, most of which ends up in landfills. Ceramic stoneware is a type of ceramic known for its strength and durability that is created at very high temperatures (1,200ºC). This study examines using waste ceramic stoneware as a recycled aggregate to create structural concrete and its properties at high temperatures. Five concrete mixes are studied: the reference, and different replacements of natural calcareous sand and gravel with fine and coarse ceramic stoneware waste. The study evaluates the properties of aggregates, such as size distribution, density, absorption, and hardness, and looks at the properties of the resulting concrete mixes. Concrete is tested for compression, and also for thermal conductivity at room temperature. Concretes compressive strength is also evaluated after being exposed to high temperatures (200ºC, 400ºC, 600ºC, 800ºC), with air cooling. The results show that the strength values obtained at room temperature are similar in all the mixes. Thermal conductivity decreases as the percentage of ceramic waste rises. Finally, replacing natural aggregates with ceramic stoneware offers significant improvements to concrete’s residual compressive strength after being exposed to 400ºC and 600ºC. This was observed mainly with a high replacement percentage. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.