Sustainable use of waste marble powder and reclaimed asphalt pavement as aggregates in slag/metakaolin-based self-compacting geopolymer composites: Properties and durability

Geopolymer concrete (GPC) is widely recognized for its reduced carbon footprint compared to traditional concrete. By integrating self-compacting properties, self-compacting geopolymer composites (SCGC) offer sustainable solutions that reduce manual labor, minimize noise pollution, and ensure superior finishes. This study aims to assess the effects of curing temperatures (50 degrees C and 75 degrees C for 8 h), metakaolin (MK) content (0 and 10% as a substitute for ground blast furnace slag (GBFS)), and reclaimed asphalt pavement (RAP) aggregates (replacing waste marble powder (WMP) at levels of 0%, 10%, 25%, and 50% by volume) on the fresh, mechanical, durability, and microstructural properties of slag/MK-based SCGC. The reference mixture (100% GBFS, 0% RAP, 0% MK) achieved a compressive strength of 50.76 MPa under 75 degrees C curing conditions, which decreased by 38%-56% with RAP addition. However, incorporating 10% MK mitigated strength losses and enhanced durability, resulting in a maximum compressive strength of 53.34 MPa (at 75 degrees C without RAP). RAP inclusion improved flowability and yielded comparable high-temperature resistance up to 800 degrees C but led to increased porosity and reduced density. The novelty of this study lies in its unique combination of RAP and WMP in SCGC mixtures, expanding the sustainable use of industrial byproducts. The findings contribute to the circular economy by showcasing the potential of using waste materials as partial aggregate replacements, balancing environmental benefits with mechanical performance. This work pioneers a pathway for developing durable, eco-friendly composites for construction applications under diverse environmental conditions.