MULTISCALE ANALYSIS OF STRUCTURAL PERFORMANCE AND FAILURE MECHANISMS IN LAYERED REINFORCED CONCRETE BEAMS WITH RIVER GRAVEL AND CRUSHED COARSE AGGREGATE INTERFACES
The structural performance and failure mechanisms of layered reinforced concrete (RC) beams incorporating river gravel and crushed coarse aggregates were investigated through a multiscale analysis. The experimental program involved testing six small-scale reinforced concrete (RC) beams (0.9 × 0.075 × 0.112 m) were tested for bending strength, including two monolithic (NA, RV) and four layered configurations (50RVT, 50RVB, 30RVT, 70RVB). Monolithic beams used uniform aggregates: crushed natural aggregates (NA) or river gravel (RV). Layered beams combined materials: 50RVT and 50RVB had equal 56 mm layers with varying aggregate placement, while 30RVT and 70RVB had unequal layer thicknesses. All beams were reinforced with 2Y8 bars at the bottom and 2R6 bars at the top, with a tensile reinforcement ratio of 0.013. These variations explored material placement and thickness effects on performance. Beams were subjected to third-point loading to evaluate load-carrying capacity, ductility, stiffness, and cracking behavior. Results demonstrated that the NA beam achieved the highest stiffness and load-carrying capacity due to uniform crushed aggregates, though at the expense of ductility. The 50RVB configuration achieved the highest ductility index (2.85), balancing strength and deformability by placing crushed aggregates in the compression zone and river gravel in the tensile zone. Unequal layer thicknesses, as in 30RVT and 70RVB, reduced structural efficiency due to limited stress distribution. This study concludes that strategically layering crushed aggregates and river gravel optimizes RC beam performance. Placing crushed aggregates in the compression zone and river gravel in the tensile zone provides an effective balance between strength and ductility, contributing to sustainable and resilient RC beam designs.
Keywords: Bending, Crushed aggregates, Ductility, layered beam, Load, River gravels
