Improvement of concrete strength owing to confinement by lateral reinforcement is disregarded in the current concrete design practice. The focus of this study is to use the pre-existing lateral reinforcement to enhance the behaviour of recycled aggregate concrete (RAC). The stress strain performance of steel spiral confined concrete specimens with different confinement pressure, recycled aggregates (RA) replacement ratio and target strength is studied. The results show a decrease in compressive strength of concrete with the rise in RA replacement ratio. Around 43, 37 and 33% drop in the strength is observed for 100% RA replacement ratio having different target strengths of NAC (i.e., 25, 40 and 60 MPa). However, steel confinement has a positive role to offset the negative effect of RA on strength. The rise in the confinement pressure results in improved ductility and stress strain behaviour of RAC. Due to scant research work related to steel spiral confined RAC, existing models cannot estimate the stress strain performance of steel spiral confined RAC effectively. Therefore, a new model is developed in this study, considering a large experimental program. The newly developed model can be effectively used to predict the stress strain performance of both steel spiral confined normal aggregate concrete and RAC, which provides guidelines for the design of RAC members. Furthermore, a relationship is also developed to determine the allowable content of RA for given confinement without affecting the concrete strength, which may be used to decide the allowable content of RA in designing the RAC compression members.

在当前的混凝土设计实践中，忽略了由于侧向加固而导致的混凝土强度的提高。这项研究的重点是使用预先存在的横向钢筋来增强再生骨料混凝土（RAC）的性能。研究了不同围压，再生骨料置换率和目标强度下的钢螺旋承压混凝土试件的应力应变性能。结果表明，随RA置换比的增加，混凝土的抗压强度降低。对于具有不同NAC目标强度（即25、40和60 MPa）的100％RA替代率，观察到强度下降了约43、37和33％。但是，钢限制对抵消RA对强度的不利影响具有积极作用。围压的上升导致RAC的延展性和应力应变行为得到改善。由于关于钢螺旋承压RAC的研究很少，现有模型无法有效估计钢螺旋承压RAC的应力应变性能。因此，考虑到大型实验程序，本研究开发了一种新模型。新开发的模型可以有效地预测钢螺旋承压普通骨料混凝土和RAC的应力应变性能，为RAC构件的设计提供指导。此外，还开发了一种关系，用于确定给定限制下的RA允许含量而不影响混凝土强度，这可以用来确定RAC压缩构件设计中RA的允许含量。