Compressive behavior of frp tubular columns with recycled concrete lumps and flowable grout

Abstract

This paper presents a study on the compressive behavior of a novel type of highly deformable hybrid FRP tubular columns. The columns consist of an FRP tube filled with large-size recycled concrete lumps (RCLs) as aggregates and flowable grout as the binding material, and are thus termed FRP-RCL-Grout (F-R-G) columns. The use of large-size RCLs (e.g., up to 63 mm RCLs for 200 mm circular columns) leads to a relatively high recycling ratio and facilitates the manufacturing process. The flowable grout can be easily poured/pumped into the FRP tube, leading to ease of construction, while the FRP tube acts as an effective lateral confining device. The experimental part of the study involved compression tests on F-R-G columns and similar columns for comparison, with the main test variables being the FRP tube thickness, the size of the RCLs, the compressive strength of the concrete for producing RCLs and the WP ratio of the grout. The test results showed that F-R-G columns possess excellent structural behavior including ample ductility, and clarified the effects of the key parameters. In addition, based on the test results, a simple yet accurate model is proposed to predict the strength of F-R-G columns.