Experimental study on using recycled polyethylene terephthalate and steel fibers for improving behavior of RC columns

Abstract

In this research, the behavior of RC columns reinforced with recycled polyethylene terephthalate (PET) fibers and steel fibers (SFs) was experimentally investigated. The experimental work included testing of 8 columns with the dimensions of 150 × 150 × 1000 mm subjected to the axial loading up to failure. Three volume fractions (1%, 2%, and 3%) were considered for both PET fibers and SFs. The axial/lateral displacements of the columns and the transverse/vertical strains versus the loads of the bars were recorded. The peak load, yield load, failure mode, ductility, and stiffness of the columns were studied in detail. The effects of plastic fibers (PFs) and SFs on the concrete characteristics were experimentally examined. Using 2% SFs in the mix increased the compressive strength, tensile strength, and toughness of concrete by 12.7%, 87.6%, and 304.8%, respectively. Furthermore, enhancement rates of the ultimate load capacity, stiffness, and ductility of the columns with 2% SFs were 15.6%, 72.6%, and 34.29%, respectively. The ultimate load capacity, initial stiffness, and ductility of the columns reinforced with 1% PF fiber were 9.43%, 62.6%, and 19.4%, respectively, greater than those of the columns without fibers. The columns’ capacity was decreased with increasing SFs and PFs over 2%. An equation from ACI was used to predict the columns’ capacity and the results agreed well with the experimental results.

Keywords

• RC column
• Recycled polyethylene terephthalate fiber
• Steel fiber
• Peak load
• Deformation
• Ductility