Axial stress–strain behaviour of bamboo composite tube-confined recycled aggregate concrete with different aggregate replacement ratios

Abstract

ABSTRACT As an eco-friendly material, recycled aggregate concrete (RAC) has lower strength than natural aggregate concrete. To improve the compressive behaviour of RAC, a bamboo composite tube (BCT) is selected as the confining jacket. A total of 60 specimens were tested, which included 45 bamboo composite tube-confined recycled aggregate concrete (BTRAC) specimens and 15 unconfined RAC specimens. To investigate the influence of the replacement ratio of the recycled aggregate and thickness of BCT, a series of analysis were conducted on the failure modes, stress–strain response, dilation behaviour and effect of the replacement ratio. Test results showed that the axial stress–strain curves of the BTRAC specimens were approximately bilinear. The confinement ratio was found as the primary factor affecting the mechanical properties of the BTRAC column. Owing to a greater confinement stiffness in a thicker BCT, the slope of the second stage in the stress–strain curves increased correspondingly. Although the change in replacement ratio of recycle aggregate resulted in different dilation behaviours, the influence was regarded as limited on the BCT confinement effectiveness. Moreover, the ultimate stress, the ultimate strain, and the axial stress–axial strain curves of BTRAC specimens were calculated by the relevant models for FRP-confined concrete to evaluate their applicability.