Theoretical study on mechanical behavior of steel confined recycled aggregate concrete

A theoretical study of the mechanical response of recycled aggregate concrete (RAC) confined by steel tubes under axial compression is conducted to examine the sensitivity of the confining pressure on the strength and deformation of RAC. The main parameter in this analysis is the recycled coarse aggregate (RCA) replacement percentage. The axial stress–strain relationship of confined RAC is obtained based on the elastoplasticity and verified by experimental results. It is found that the development of the confining pressure can be divided into three sections: linear increase, nonlinear increase and relatively smooth increase. The mechanical proprieties of confined RAC are dependent on the variation of the confining pressure. The analysis results indicate that the assumption of constant confinement or elastic–plastic confinement is not appropriate for concrete confined by steel tubes and the RCA replacement percentage has a moderate effect on the mechanical response of the confined concrete. Finally, a simple model for the constitutive relationship of RAC under varying pressures and different RCA replacement percentages is proposed.

► The main parameter is the recycled coarse aggregate (RCA) replacement ratio.
► Mechanical response of confined recycled aggregate concrete (RAC) is obtained.
► Constant confinement is not appropriate for RAC confined by steel tubes.
► A simple model for confined RAC under varying pressures is given.