Mechanical properties of confined recycled aggregate concrete under axial compression

This paper presents the results of axial compression tests on recycled aggregate concrete (RAC) confined by steel tubes and RAC confined by glass fiber reinforced plastic (GFRP) tubes. The objective of this study is to evaluate the mechanical properties of confined RAC under axial compressive loading. The main parameters in the tests are the recycled coarse aggregate replacement percentage and the tube material. Research findings indicate that both the strength and deformation of RAC are obviously improved. The mechanical properties of RAC confined by steel tubes are better than those of RAC confined by GFRP tubes when all parameters are kept the same. It is also found that the peak stress of RAC confined by steel tubes decreases while the corresponding strain increases when the replacement percentage of RCA is increased, which are similar to those of RAC confined by GFRP tubes. Expressions for the peak stress and the stress–strain relationship of the confined RAC are then obtained based on the test data. Finally, the finite element method (FEM) is applied to study the effect of the outer tube thickness and the core RAC strength on the stress–strain relationship of confined RAC.