RESEARCH PAPER Effect of Recycled PET (Polyethylene Terephthalate) on the Electrochemical Properties of Rebar in Concrete Yohandry Dı ´az Blanco 1 • Elsa Carmina Menchaca Campos 1 • Carolin Ivette Rocabruno Valde ´s 1 • Jorge Uruchurtu Chavarı ´n 1 Received: 20 November 2018 / Revised: 22 September 2019 / Accepted: 30 October 2019 Ó Iran University of Science and Technology 2019 Abstract This research is focused on the use of recycled PET (Polyethylene terephthalate) as an aggregate to improve the elec- trochemical 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 (R n ) and polarization resistance (R p ) 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 9 10 -1 lA/cm 2 . 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 9 10 -1 and 5 9 10 -1 lA/cm 2 , similar to the control sample. Keywords Reinforcing concrete  Recycled PET  Electrochemical techniques  Localized corrosion 1 Introduction Corrosion of reinforcing steel is the main cause of deteri- oration of reinforced concrete structures [1–3]. In the last decades, numerous investigations have been carried out in this field. The reinforcement corrosion process in concrete is influenced by several factors such as: the design of the mixture, the chemical composition of the solution inside the pores, the characteristics of the concrete cover, the curing process, among others [2]. The causes that most affect steel corrosion are (1) depassivation of reinforcing steel due to localized attack of chloride ions, which enter through to the concrete pore network [4–6] and (2) gen- eralized corrosion of steel due to a process of carbonation in concrete, as a consequence of reactions of the cement matrix and carbon dioxide present in the atmosphere [5–7]. The concrete offers a double protection to the rein- forcing steel. First, the concrete acts as a physical barrier, isolating the reinforcing steel from the surrounding envi- ronment, which hinders the entry of aggressive agents. In addition, the high alkalinity of the concrete provides a pH between 12 and 13, and at this pH, the steel forms a compact and passive film [6, 8]. Currently, many concrete structures lose these characteristics at an early age. Due to & Jorge Uruchurtu Chavarı ´n juch25@uaem.mx Yohandry Dı ´az Blanco yohandry.diaz@alumnos.uaem.mx Elsa Carmina Menchaca Campos cmenchaca@uaem.mx Carolin Ivette Rocabruno Valde ´s carolin.rocabruno@uaem.mx 1 Centro de Investigacio ´n en Ingenierı ´a y Ciencias Aplicadas (CIICAP), Instituto de Investigacio ´n en Ciencias Ba ´sicas y Aplicadas (IICBA), Universidad Auto ´noma del Estado de Morelos, Av. Universidad No. 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos, Mexico 123 International Journal of Civil Engineering https://doi.org/10.1007/s40999-019-00478-3