Deformation performance and strength criterion of recycled concrete at early age subject to tri-axial compression

In order to study the deformation performance of recycled coarse aggregate concrete at early age under tri-axial compression, 14 cylinder specimens were designed for tri-axial test, and two parameters were considered in the test, which were lateral confinement and age of concrete. The stress-strain curves and characteristic parameters were obtained by the test. The influences of time age and lateral confining pressure on the peak strain, elastic modulus, ductility and energy dissipation properties under conventional tri-axial compression were analyzed. Finally, the MOHR-COULOMB theory was used to discuss the recycled concrete strength criterion. The experimental results show that, lateral compression has a great influence on deformation performance. The increase of lateral compression can effectively improve the peak strain, modulus of elasticity, ductility and energy dissipation performance. The longer the time age, the smaller peak strain, the greater the modulus of elasticity and the better ductility performance of recycled concrete under tri-axial compression.