Uso de resíduos de pisos cerâmicos para produção de concreto

Abstract

The reuse of ceramic floor tile waste as aggregates in concrete is a promising alternative to reduce the demand for natural resources; however, studies evaluating the simultaneous replacement of fine and coarse aggregates under an integrated performance approach, including post-aging verification, are still limited. Thus, the study evaluated the effects of replacing natural aggregates with ceramic tile waste in the fine and coarse fractions for concrete production, at 28 days and after accelerated aging.. Concretes were produced with a control mix and mixtures with 10% and 20% substitution of fine aggregate, 25% and 50% of coarse aggregate, as well as simultaneous combinations of aggregates. The waste was characterized in terms of particle size distribution, density, and water absorption, as well as by X-ray fluorescence (XRF) and compatibility with cement; in the concrete, slump, water absorption, void index, density, and microstructural evidence were evaluated, in addition to compressive strength, thermal conductivity, and acoustic insulation. The results indicated a low inhibition index, suggesting a nearly neutral effect of the waste on hydration, and low to medium workability in the fresh state. Water absorption and void index were the most sensitive properties, where moderate substitutions in the fine fraction maintained performance equivalent to the reference, and high substitution levels in the coarse and combined fractions with higher content showed the worst results, in agreement with the microstructural evidence; after aging, the formulation made with only 20% fine residue substitution obtained the best result for these properties. In terms of mechanical performance, at 28 days m20 presented the highest value (30.1 MPa), and after accelerated aging, most mixtures maintained or increased their strength, with the exception of the m10G25 treatment. Thermal conductivity remained statistically equivalent among the mixtures, and acoustic performance met the minimum requirement of 40 dB, with greater insulation observed after aging. It is concluded that technical feasibility is favored at moderate replacement levels and depends mainly on the granulometric balance and its effects on pore connectivity and the integrity of the interfacial transition zone (ITZ).