Advancement of plant-based inhibitor acquired from Elaeocarpus aungustifolius Blume leaves to control carbon steel corrosion in simulated concrete pore solution

Abstract

The extraordinary compressive strength of concrete makes it one of the most popular building materials, second only to water. However, early reinforcement corrosion is a common problem with concrete structures reinforced with carbon steel (CS). This issue underscores the significance of understanding corrosion-retarding systems that incorporate inhibitors. This research evaluates the effectiveness of leaf extract from Elaeocarpus angustifolius Blume (LEEA) as an environmentally friendly corrosion inhibitor in a saturated calcium hydroxide solution that simulates a concrete pore solution (SCPS) with a pH level exceeding 11.5. The objective was to evaluate the corrosion-inhibiting capacity of LEEA at concentrations of 500, 1000, 2000, and 4000 ppm in SCPS to reduce reinforcing carbon steel (RCS) corrosion at a laboratory temperature of 298K over four months or more using gravimetric weight loss (GrWL) and electrochemical polarization (ECP) techniques. GrWL and ECP methods yielded the maximal inhibition efficiencies of 93.9% and 81.7%, respectively, at 4000 ppm LEEA in SCPS. The results of ECP experiments demonstrated that the corrosion current density (CCD) decreased with increasing LEEA concentrations. This observation indicates that LEEA exhibits a significant inhibitory effect in the SCPS environments. Phyto-compounds (PCs), including polyphenols, alkaloids, and flavonoids found in LEEA, can inhibit both cathodic and anodic (i.e., mixed) processes by promoting the best-fitting Langmuir adsorption isotherm model on the RCS surface. Surface analyses, such as white light interferometry (WLI), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), confirmed the corrosion-inhibiting effectiveness of LEEA in enhancing concrete's anti-corrosion properties through a passive layer on RCS.