Utilizing Waste-Plastic Pipes as Hoops in Circular Concrete Columns

In this study, traditional steel hoops in circular concrete columns are replaced with waste-plastic pipe slices having three different geometrical sections where the thickness t=5.3mm and the height H1=5.3 mm, H2=10.6 mm and H3=15.9 mm, with different replacement ratios of 35%, 65%, and 100%. Waste plastics have become a major issue on a global size and this work is part of the efforts to reduce its exacerbations through utilizing it not only in conventional concrete but rather as an alternative secondary reinforcement for the structural members especially for infrastructures with aggressive environmental exposure. The behaviour of the proposed plastic hoops is experimentally investigated throughout axially testing 10 circular concrete columns having a diameter of 160 mm and a height of 950 mm containing plastics (UPVC) as hoops with different types and replacement ratios compared with columns containing conventional steel hoops. The results indicate that the behavior of columns with UPVC hoops of the first type (H1) and the second type (H2) with replacement ratio of 65% has been more ductile and had better confinement efficiency of the concrete core without damage or rupture compared to corresponding columns containing traditional steel hoops. In some of the specimens an increase in axial load capacity of 31%, axial strain of 30%, ductility index up to 8% and stiffness up to 196% are recorded compared with reference specimen. The results of this work strongly suggest that using UPVC closed loop hoops for circular reinforced concrete columns is a valid option with high potentials to replace the conventional steel hoops without affecting the capacity of the column section.