A sustainable approach for mitigating rebar corrosion in adverse conditions using Phyllanthus emblica (L.) leaf extract as concrete scale inhibitor

• M. Gautam^1,2, D.B. Subedi¹, J.R. Dhungana¹, M. Dhakal^1,3, K.P. Bohara¹, N.P. Bhattarai¹ and J. Bhattarai¹

¹ Central Department of Chemistry, Tribhuvan University, Kirtipur 44618, Kathmandu, Nepal
² Department of Chemistry, Tribhuvan M. Campus, Tribhuvan University, Tansen 32500, Palpa, Nepal
³ School of Material Science & Engineering, University of Science & Technology of China, Hefei 230036, China

Abstract: The primary challenge of reinforced concrete infrastructures (ReCIs) is the early corrosion damage of their reinforcing mild steel (ReMS). Effective and sustainable approaches are needed to reduce reinforced concrete corrosion (ReCC). This research evaluates the effectiveness of Phyllanthus emblica (L.) leaf extract (PEL) as a concrete inhibitor for the first time, aiming to minimize the early corrosion risk of ReMS in three harsh circumstances such as simulated industrial environment (SIdE), simulated coastal environment (SCoE), and ordinary environment (OrdE) of ReCIs. To achieve this, fifteen reinforced concrete cuboid beams (RC2Bs) were formulated using concrete mixes with varying PEL concentrations (500 ppm, 1000 ppm, 2000 ppm, and 4000 ppm) in these three harsh electrolytes. The study measured the corrosion potential (E_cor) and electrochemical resistivity (EChR) of the ReMS rod in the RC2Bs at regular intervals until seven months. The measurement of the electrochemical parameters E_cor and EChR has shown an effective, sustainable, and cost-efficient method for monitoring the condition of ReCC in real-time and on-site, following the ASTM C876-22b. Screening tests, including UV-Vis spectroscopy, FTIR, and GC-MS/UHPLC-MS, confirmed the presence of secondary metabolites (SMBs) in PEL, which act as anti-corrosive agents to help prevent early corrosion of reinforcing steel in concrete beams. The E_cor value improved to –125 mV (SCE) or more positive potential, and the EChR increased by more than 20 kΩ·cm with high PEL concentrations after seven months of exposure, indicating a lower corrosion risk of the ReMS. Surface analyses of the ReMS rods were conducted before and after reinforcement in the RC2Bs, validating the electrochemical findings.

Keywords: effective inhibitor, emblica leaf extract, marine and industrial conditions, SEM-EDS, rebar coatings

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1522-1554
doi: 10.17675/2305-6894-2025-14-3-26

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