Axial compressive behavior of environmentally friendly high-strength concrete: Effects of recycled tire steel fiber and rubber powder

Ultra-high-performance concrete (UHPC) has ultrahigh strength and excellent durability but its widespread application is limited by its high cost and carbon emission. In this study, an environmentally friendly high-strength concrete (E-HSC) with low CO2-e emission was developed with the utilization of recycled tire steel fiber and rubber powder. The axial compressive behavior of E-HSC was investigated with recycled rubber powder partially replacing fine aggregates (0%, 5%, 20%, 35%, and 50%) and varying recycled steel fiber content (1%, 2%, 3%). The physical and mechanical properties of E-HSC were analyzed and compared with normal UHPC and high-performance rubberized concrete. The results show that the compressive behavior of E-HSC is determined by the mechanical properties and interaction among the rubber, cement matrix, and recycled steel fiber. Under the condition of rubber powder content (<= 5%/<= 35%), the compressive strength of E-HSC can still achieve the standard of ultra-high/high-performance concrete (>= 120 MPa/>= 50 MPa), of which ductility and toughness index were enhanced. A new constitutive model was proposed to describe the stress-strain behavior of E-HSC by considering the contents of recycled steel fiber and rubber powder. This study provides test data and design theory for the development of E-HSC.