Performance of self-compacting concrete with recycled sanitary ware ceramic aggregate

The increasing demand for sustainable solutions in the construction sector has encouraged the use of industrial waste as a substitute for natural aggregates, especially when such residues present compositional uniformity, controlled origin, and low contamination risk. In this context, recycled sanitary ware ceramic aggregate (SWA) is a promising alternative to natural fine aggregate. However, evidence remains limited on how a broad SWA replacement range affects the balance between self-compacting behavior and hardened performance in self-compacting concrete (SCC). This study aims to investigate the feasibility of using SWA as a partial replacement for natural fine aggregate in SCC. SWA replacement range was evaluated in two sequentially and independent SCC mixture-design series by integrating fresh-state, mechanical, physical, transport-related, and microstructural properties under different matrix conditions. SCC1 covered 0–100% replacement to map the full performance envelope, with water and superplasticizer adjustments as required, whereas SCC2 evaluated 0–50% replacement in a distinct granular skeleton with water and superplasticizer contents held constant. Fresh-state, mechanical, physical, transport-related, and microstructural properties were jointly assessed. SWA effects were most pronounced in the t₅₀₀, V-funnel, and J-ring tests, reflecting higher viscosity and lower passing ability, VSI remained unchanged. Nevertheless, intermediate replacement levels improved the hardened performance. The 28 day mean compressive strength increased from 31.87 to 71.87 MPa at 50% SWA in SCC1 and from 38.83 to 56.90 MPa at 25% SWA in SCC2. These mixtures also exhibited improved stiffness-related properties and lower water-accessible porosity relative to their respective references. These results support the potential use of SWA as fine aggregate in SCC, with 50% in SCC1 and 25% in SCC2 providing the best balance between self-compacting behavior and hardened performance among the levels tested.