Effect of Recycled PET (Polyethylene Terephthalate) on the Electrochemical Properties of Rebar in Concrete

Abstract

This research is focused on the use of recycled PET (Polyethylene terephthalate) as an aggregate to improve the electrochemical properties of reinforcing steel in concrete. Samples were made with different PET geometries such as: fibers (F), rectangles (R), and mixture of fiber and rectangle (F–R). The PET was added as a substitute for sand with a PET/sand ratio by volume percent of 3%/97%, 5%/95%, and 8%/92%. Specimens were exposed to an aggressive solution of sodium chloride at 3%, simulating a marine environment, and were evaluated for 300 days through various electrochemical techniques such as: open-circuit potential, electrochemical noise, electrochemical impedance spectroscopy, and linear polarization resistance. Samples with PET reached more noble values of potential compared to the control sample. The highest values of noise resistance (Rn) and polarization resistance (Rp) were reached for the reinforcing steel in concrete samples prepared with particle of rectangles and fiber–rectangle mix. Likewise, these samples maintained a diffusive behavior for a longer time. At the end of the test period, the favorable effect of the rectangles and the mixture of fibers and rectangles in the concrete samples are evident, since they remain in the negligible range of corrosion rate, with values below 1 × 10−1 μA/cm2. This behavior was not noticeable for samples with only PET fibers, due to the fact that they reach the moderate range of corrosion rate, with values between 2 × 10−1 and 5 × 10−1 μA/cm2, similar to the control sample.