70 / 2022-04-12 16:40:01

Compound Concrete Filled FRP Tubular Columns Containing Recycled Concrete Lumps

Fiber reinforced polymer (FRP),Recycled concrete lumps (RCLs),Compound concrete,FRP tubes,Size effect

A recently proposed technique of recycling waste/old concrete is to directly mix large pieces of recycled concrete lumps (RCLs) and fresh concrete to form the so-called “compound concrete”. This novel technique has a much more simple and cost-effective recycling process and a much larger recycling ratio compared with conventional recycling techniques (e.g., recycled aggregates). However, due to the low strength and internal weaknesses of RCLs, compound concrete generally exhibits inferior performance with large scatters compared with normal concrete. Confining compound concrete through a steel tube has been explored by researchers to improve the behavior of compound concrete. However, it was found that the detrimental effects of RCLs can be eliminated or minimized only when a thick steel tube (i.e., one with a small diameter/width-to-thickness ratio) is used. The authors’ group has recently explored the use of an external fiber-reinforced polymer (FRP) confining tube to confine compound concrete, which has been shown to be an effective technique to improve the mechanical properties and durability of compound concrete. The resulting columns, referred to as Compound Concrete Filled FRP Tubular (CCFFT) columns, can possess performance comparable to the columns without RCLs. This paper presents a comprehensive review on existing research conducted by the authors’ group on FRP-confined compound concrete and CCFFT columns, as well as their size effect. The future research on CCFFT columns for their wide application in practice is also highlighted.