Eleven-Year Follow-Up on the Effect of Thermoplastic Aggregates' Addition to Reinforced Concrete

An experimental investigation was carried out to study the effect of thermoplastics' addition to reinforcement corrosion and the durability of concrete. A long-term study is necessary for the final decision on the possibility of the utilization of materials, and this study is contributing to this direction. Two types of thermoplastics were used, high-density polyethylene and polypropylene. The percentage of replacement of conventional aggregates was 0% and 12% by volume. After being demolded and cured for 7 days, the specimens were immersed in 3.5 wt% NaCl solution for 240 days. Afterwards, they were left in laboratory ambient air up to 11 years. Carbonation depth and the volume of permeable voids were determined. Optical microscopy, stereoscopy, and electrochemical impedance spectroscopy measurements were performed. Results showed that replacing conventional limestone aggregates with the particular two thermoplastics does not have a negative impact on rebars' corrosion behavior. Optical microscopy and stereoscopy of rebars' surface revealed that the corrosion process has initiated and carbonation is observed in all mixes, but corrosion rates are negligible for all the mixes studied.