The Use of Demolished Concrete Lumps (DCL) in Rectangular CFSTs Under Flexure

Abstract

This paper investigates the flexural performance of rectangular concrete-filled steel tube (CFST) beams that are partially incorporated with demolished concrete lumps (DCLs). In total, three CFST beams were prepared and tested under flexure through a four-point bending setup. These three specimens are selected from a bigger ongoing research project that considers further parameters. The three beams varied in the presence of DCLs within the CFST section and the maximum particle size of the DCLS. The DCLs were mixed with mortar and were isolated at the center of the CFST section and surrounded by normal concrete. The flexural behavior of the CFST beams was analyzed and discussed through the use of moment versus displacement, moment versus strain, and deflected shape graphs. The test results showed that the CFST beams with partially incorporated DCLs had similar flexural behavior to the normal CFST beam. The displacement at ultimate capacity was reported to be lower for the beams with incorporated DCLs, especially the beam with the higher DCL maximum particle size. However, the displacement at yield was found to be lower for the specimen that was fully cast with normal concrete. Finally, it was observed that the failure mode was the same for all three beams.