Document Type : Original Article

Author

• Arash Bayat

Department of Civil Engineering, Instructor, Razi University, Kermanshah, Iran

Abstract

Given the vast consumption of concrete today, recycling demolition waste and its reuse is considered a key strategy for improving environmental sustainability. The present study evaluates the impact of parent concrete quality on the mechanical properties and impact performance of steel fiber-reinforced recycled aggregate concrete (RAC). For this purpose, coarse aggregates were sourced from two types of parent concrete with different strengths (Series A and B) and used to replace natural aggregates at levels of 0%, 50%, and 100%. Additionally, steel fibers were added at a volume fraction of 1% to enhance ductility. Experimental results for compressive strength, tensile strength, and drop-weight impact (according to ACI 544) indicated that Series B recycled aggregates led to a 9% improvement in 91-day compressive strength, attributed to stronger mechanical interlocking in the new Interfacial Transition Zone (ITZ). Furthermore, steel fibers compensated for the inherent tensile weakness of recycled concrete through the stitching effect mechanism, shifting the failure mode from brittle to ductile. The results revealed that fibers significantly increased the interval between the first crack ($N_1$) and final failure ($N_2$) blows, an effect that was more pronounced in recycled concrete. Ultimately, the findings suggest that a 50% replacement level of recycled aggregate combined with steel fiber reinforcement serves as an optimal replacement level to achieve performance competitive with conventional concrete.

Keywords

• Recycled Aggregate Concrete
• Steel Fiber
• Impact Resistance
• Parent Concrete
• Interfacial Transition Zone (ITZ)

Main Subjects

• structure