Enhanced impact resistance of novel sustainable preplaced aggregate geopolymer concrete reinforced with steel mesh and 5D fibers

The rising demand for sustainable concrete stems from resource scarcity, environmental concerns, and structural performance needs. Preplaced Aggregate Concrete (PAC) improves durability and efficiency but requires alternative binders to lessen dependence on Portland cement. This study explores the formulation of a sustainable geopolymer grout, incorporating red clay, slag, and fly ash, to address these concerns while promoting the reutilization of industrial by-products. This study investigates the synergistic integration of steel wire mesh (SWM) and advanced 5D steel fibers (2.5% by volume) to improve the impact resistance of PAC. Five distinct mesh sizes (M40, M30, M20, M10 and M5), with diameters ranging from 75 mm to 150 mm at 25 mm intervals, were strategically placed at the mid-height of the PAC. A total of 42 mixing combinations were developed and categorized into 10 groups based on variations in steel wire mesh sizes and fiber configurations. All specimens underwent evaluation using the drop-weight impact test in conformity with ACI Committee guidelines. The innovation combines sustainable geopolymer binders with hybrid reinforcement, creating a concrete system with enhanced impact strength. Microstructural analysis was also performed on the geopolymer grout used in PAC. SWM integration in PAC notably enhances failure impact number, especially with larger diameters (150 mm), while first crack sees only slight improvement. Combining SWM with steel fibers consistently boosts both initial crack and failure by improving crack control and energy absorption. Larger SWM diameters (e.g., 150 mm) lead to more distributed failure patterns and better energy dissipation than smaller diameters (e.g., 75 mm).