Exploration of plant-based leaf extracts as anti-corrosive concrete admixtures for extending the service life of reinforcement concrete infrastructures

This study intended to improve the service life of reinforcing mild steel (MS) within concrete beams (CBs) by incorporating leaf extracts from Justicia adhatoda L. (JAL) and Persea americana Mill. (PAL) as concrete admixtures in corrosive environmental conditions. The research involved monitoring the corrosion susceptibility levels of mild steel-reinforced concrete beams (MS-CBs) with varying concentrations of JAL and PAL extracts—specifically, 500, 1000, 2000, and 4000 ppm. Half-cell potential (HCP) and electrical resistivity (ER) data were collected for seven months or more, following ASTM standards, and were recorded at various time intervals to ensure accurate assessment. The outcomes indicated that the corrosion resistance of the MS in CBs significantly improved with 500-4000 ppm of these extracts as a concrete admixture, as compared with the corrosion level of the MS-CBs without extract (control). Phyto-screening analysis has identified key bioactive components, including alkaloids, flavonoids, and tannins. FTIR and UV-visible analysis results validate the conclusions drawn from the phyto-screening tests. Scanning electron microscopy (SEM) analysis provides pertinent surface information regarding the MS in CBs, yielding valuable insights into the chemical composition that may facilitate the development of novel anti-corrosive films for corroded MS, thereby mitigating early corrosion damage in MS-CBs and elucidating the corrosion inhibition mechanism. The study highlights the potential of plant-based inhibitors to enhance the durability of reinforced concrete, offering practical benefits for infrastructure longevity and guiding future research in sustainable construction materials.