Sustainable high-performance concrete: harnessing recycled rubber and slag for strength and eco-friendliness

This study proposes a sustainable high-performance concrete (HPC) incorporating industrial by-products and recycled materials, specifically granulated blast furnace slag and recycled rubber powder, as partial replacements for cement. A series of experimental tests were conducted to evaluate the mechanical performance of the modified concrete, including compressive, flexural, and Brazilian tensile strengths, along with workability characteristics. Results indicate that replacing cement with up to 30% slag resulted in less than 5-10% reduction in mechanical strength, while significantly improving workability. The inclusion of 10% recycled rubber powder enhanced ductility and fracture energy albeit with an associated reduction in compressive strength from 89 to 73 MPa. From an environmental perspective, carbon footprint analysis revealed that cement replacement led to substantial CO₂ emission reductions, with a 42% reduction at 30% slag and up to 37% reduction at 30% rubber content compared to conventional HPC. Life cycle cost analysis further demonstrated that the mix containing 30% slag achieved the highest strength-to-cost efficiency (0.22 MPa/$), highlighting its economic viability. Overall, the findings demonstrate that combining slag and recycled rubber offers an effective pathway toward environmentally friendly and cost-efficient HPC, suitable for sustainable construction applications where reduced carbon emissions, enhanced energy absorption, and adequate structural performance are required.