Carbonation curing of lightweight cementitious composites incorporating copper tailings and limestone: CO2 uptake, pore restructuring, and high-temperature performance

Lightweight cementitious composites containing copper tailings and limestone powder were prepared by chemical foaming followed by carbonation curing. The three mineral-replacement mixtures exhibited larger cross-sectional carbonation area ratios than the OPC reference, exceeding 80% after 3 days. After 14 days of carbonation curing, C40-C exhibited the highest TG-based net CO 2 uptake among the three blended mixtures, reaching 15.55 wt.% on the normalization basis defined in this study. Limestone-associated filler and nucleation effects influenced early hydration and aluminate-related reactions. The MIP results indicated a non-uniform redistribution of the mercury-accessible pore network, consistent with localized carbonate filling and partial pore-throat coarsening. C30L10-C achieved a compressive strength of 27.8 MPa after 14 days and exhibited relatively favorable residual strength retention at 600 °C. However, severe strength deterioration occurred at 900 °C. These results identify composition-dependent differences in carbonation response, strength development, and high-temperature performance within the investigated lightweight cementitious system.