Industrial internal recycling: aggregate substitution for decorative concrete tiles

In developing countries, the use of recycled aggregates can be an opportunity to combine economic, environmental, and sustainability benefits. Therefore, this research investigates an industrial internal recycling approach by reinserting residues from concrete-based tiles produced by a company in the south of Brazil into the production of new concrete tiles, using them as recycled aggregate in the partial replacement of natural aggregates and cement, simultaneously. The methodology comprised recycled aggregate preparation, material characterisation, production of concrete specimens using different replacement contents of natural aggregate and cement, and flexural strength testing to determine the optimum replacement content. The feasibility of the partial replacement of natural aggregates and cement with recycled aggregates was demonstrated, as an 87% increase in flexural strength was achieved for specimens containing 30% cement replacement and 25% natural aggregate replacement compared with the control. This improvement was attributed to the micro-filler effect of the superfine fractions, which optimised particle packing and matrix densification. In addition, the process prevented the emission of 55.1 kg carbon dioxide per ton produced. These findings demonstrate that industrial internal recycling can simultaneously improve technical performance while reducing environmental impacts and promoting resource efficiency in the construction industry.