Mechanism-Guided Design of Rubber–Fiber Hybrid Concrete for Structural Resilience

Abstract

Problem: The incorporation of recycled rubber and fibers in concrete typically reduces compressive strength, limiting structural applications and creating a perception of inferior performance.

Method: This study introduces a stress-modifying mesoscale phase in the form of a pre-mixed rubber–fiber hybrid (CRH) composite, designed as a network of stress modifiers. The interfacial transition zone (ITZ) is redefined as a graded energy-dissipation region to enhance crack deflection and stress redistribution. A mechanism-based volumetric mix design approach is adopted instead of conventional percentage replacement. Performance is evaluated using novel indices: Flexural Strength Recovery Index (FSRI), Stress Redistribution Efficiency (SRE), and Energy Dissipation Potential Index (EDPI) for M30 and M40 concretes.

Key Results: Results demonstrate non-monotonic strength recovery, improved stress redistribution, and enhanced energy absorption. Moderate-to-high CRH inclusion optimizes stress transfer, while higher inclusion levels significantly improve energy dissipation, making the composite suitable for fatigue- and damage-prone structural applications.

Conclusion: The findings establish a function-based design framework for rubber–fiber hybrid concrete, shifting focus from strength loss to performance enhancement. However, the study is limited by the absence of full-scale seismic and fatigue testing, indicating scope for future validation.