This study explores the impact of incorporating recycled rubber powder and micro silica on the energy absorption, ductility, and workability of self-compacting concrete (SCC). Rubber powder replaced fine aggregates at 2–10% by weight, while micro silica was added at 0.5–4.5% of cement weight. Twelve SCC mixtures were prepared with water-to-cement ratios of 0.35 and 0.45, including control samples without additives. Compressive strength, energy absorption (derived from stress–strain curves), and workability (via slump flow tests) were evaluated after 28 days of curing, following ASTM C192 standards.
Results show that rubber content above 8% significantly reduced energy absorption due to weakened interfacial transition zones (ITZ) and increased porosity. Conversely, mixtures with 2–6% rubber powder exhibited enhanced ductility and post-peak behavior. Notably, the CR2CH5S0.5W35 mix (2% rubber powder, 5% rubber chips, 0.5% micro silica, w/c = 0.35) achieved a 47% increase in energy absorption compared to the control. Micro silica improved pore structure and ITZ bonding, mitigating some negative effects of rubber. Workability remained largely unaffected up to 4% rubber replacement, with only a 2–3% slump flow reduction, though higher rubber levels required adjusted superplasticizer dosages to meet EFNARC standards. Crack pattern analysis revealed finer cracks and improved residual strength in rubberized mixes, indicating better fracture resistance and deformation capacity.
These findings suggest that an optimal blend of recycled rubber and micro silica enhances SCC’s mechanical and dynamic properties, making it ideal for seismic-resistant structures and noise barriers. This research promotes sustainable construction by repurposing tire waste and reducing natural aggregate use.