Local bond stress-slip constitutive model between concrete and high ductility cementitious composites with totally recycled fine aggregate

High ductility cementitious composites with totally recycled fine aggregate (termed as R-HDCC) could well repair the damaged buildings due to its exceptional strain capacity and crack control ability. Meanwhile, the adoption of R-HDCC could accelerate the application of waste concrete, resulting in a reduction of environmental pollution and consumption of natural resources . Previous research has demonstrated that the interface between R-HDCC and concrete exhibited higher shear strength and deformation capacity compared to that between ordinary high ductility cementitious composite and concrete. To understand the intrinsic cooperative behavior between concrete and R-HDCC, the local bond properties were investigated through the double shear test considering the effects of concrete compressive strength , R-HDCC compressive strength and fiber volume fraction in this study. The experimental results indicated that the local strain of R-HDCC on the interface increased whereas that of concrete decreased with the increasing of x . Particularly for C4R5F15, the strain of R-HDCC at x = 90 mm was 11.12, 11.11, 11.23 times that at x = 10 mm under P1 , P2 and Pu , respectively; the strain of concrete decreased by 91.01 %, 91 % and 91.1 % as x increased from 10 mm to 90 mm under P1 , P2 , Pu , respectively. The local bond stress of bond specimens decreased at most by 54.55 % and 60.94 %, and the relative slip decreased at most by 25.26 % and 9.19 % with the increasing in x from 20 mm to 80 mm under P1 and P2 . The increasing in concrete compressive strength from 34.75 MPa to 67.76 MPa induced a 33.9 % and 60.14 % increase in the bond stress and a 18.77 % and 43.37 % increase in the relative slip at x = 80 mm on concrete/R-HDCC interface under P1 and P2 . The increasing in R-HDCC compressive strength from 33.05 MPa to 66.09 MPa led to a 29.41 % and 31.08 % increase in bond stress and relative slip at x = 80 mm on concrete/R-HDCC interface under P2 . The increasing in fiber volume fraction of R-HDCC caused the increase in the slip and bond stress at each point during elastic and hardening stages and the decrease in bond stress during crack development stage. Finally, based on the average bond stress-slip constitutive model, combined with the equilibrium equation , physical equation, and deformation coordination equation, a local bond stress-slip constitutive model was derived.