Valorization of diaper waste ash and GBFS sand in concrete: A sustainable approach for Indian construction

This study investigates incinerated diaper waste ash (DWA) as a partial cement replacement (0–20%) and granulated blast furnace slag (GBFS) sand as a fine aggregate substitute (0–25%) in concrete. Sixteen concrete mixes were tested for compressive strength, flexural and splitting tensile strength, elastic modulus, ultrasonic pulse velocity, water absorption, and resistance to sulfate and acid attack. The C0–FA10 mix (0% DWA and 10% GBFS) performed best, with a 50.66 MPa compressive strength, 5.67 MPa flexural strength, 90.13% durability, and 2.65% water absorption. The C20–FA0 mix (20% DWA and 0% GBFS) was the least effective, with a 30.01 MPa compressive strength, 25,999.70 MPa elastic modulus, 4.65% water absorption and 69.32% durability. SEM and XRD analyses showed a dense matrix with integrated GBFS and no harmful DWA phases. ANOVA results confirmed that DWA and GBFS significantly affect the properties. Machine learning models (random forest and gradient boosting) predicted compressive strength accurately (R² > 0.90). Using 10% DWA and 25% GBFS promotes sustainable waste management.