Improvement effect of carbonation curing on the performance of lightweight calcium carbide slag cement-based materials under the coupled action of sulfate attack and dry-wet cycling

To promote sustainable utilization of calcium carbide slag (CS) and rice husk while enhancing CO₂ sequestration, lightweight materials were previously developed by incorporating foam and raw rice husk into a carbonation curing calcium carbide slag cement-based matrix, and their basic properties were characterized. However, the performance evolution of carbonation curing lightweight materials under combined sulfate attack and dry-wet cycles remains unexplored, despite its critical role in service life prediction. Therefore, this study explores the impact of carbonation curing on the performance evolution of lightweight calcium carbide slag cement-based materials under combined erosion of sulfate and dry-wet cycling. Key parameters, including compressive strength, mass variation, and relative dynamic elastic modulus, are systematically evaluated. Microstructural degradation mechanisms are elucidated through XRD, TG-DTA, MIP, and SEM analyses. Results demonstrate that carbonation curing not only enhances the initial compressive strength prior to erosion but also mitigates performance deterioration during exposure. Compared to standard curing specimens, carbonation curing samples exhibit significantly lower compressive strength reduction rates (28.57–40.35 % vs. 31.59–47.83 %), reduced mass loss (1.49–9.22 % vs. 2.60–10.89 %), and higher retained relative dynamic elastic modulus (75.21–63.56 % vs. 73.47–62.33 %) after coupled erosion. Microstructural analysis reveals that sulfate attack induces expansive gypsum and AFt formation, promoting microcrack development and performance degradation. In contrast, carbonation curing refines the pore structure via CaCO 3 deposition, reducing porosity and improving resistance of specimen to sulfate-dry-wet synergy. These findings provide critical insights into the durability enhancement of sustainable lightweight construction materials in aggressive environments, supporting their practical engineering applications.