Fire-resistant mortar with waste-derived additives: machine learning prediction of compressive strength at elevated temperatures
摘要
This study evaluates the fire resistance of mortar incorporating zirconia (ZrO₂) and rice husk ash (RHA) under elevated temperatures (25–400 °C) using a cement–sand ratio of 1:3. Experimental results showed that the optimum mix with 3% zirconia and 40% RHA improved residual strength up to 200 °C, after which strength declined due to microstructural degradation. Zirconia enhanced crack-bridging and thermal stability, while RHA improved pozzolanic reactivity and densification. A dataset of 468 samples was used to train Random Forest, LightGBM, and XGBoost regressors, with XGBoost achieving the highest accuracy (R² = 0.991, MAE = 0.245 MPa, MAPE = 1.25%). SHAP analysis confirmed temperature as the most critical factor reducing strength, while curing duration and zirconia content contributed positively. These results demonstrate that integrating waste-derived additives with AI-driven modeling provides a sustainable and accurate framework for designing fire-resilient mortars with reduced dependence on empirical testing.