Embedded piezoelectric sensing for corrosion monitoring in agro-waste concrete under chloride exposure

This study presents an integrated approach combining embedded Electro-Mechanical Impedance (EMI) sensing with agro-waste-based supplementary cementitious material (SCM) concretes for early-stage corrosion detection in reinforced concrete systems. Ordinary Portland Cement (OPC 43 grade) was partially replaced with 10% Rice Husk Ash (RHA) and 20% Sugarcane Bagasse Ash (SCBA) to develop sustainable concrete mixtures. Cylindrical reinforced concrete specimens (200 × 100 mm) were cast and cured for 28 days, followed by accelerated corrosion exposure in a 3.5% NaCl solution to simulate chloride-induced deterioration. A piezoelectric PZT-5H patch was embedded within a mortar–epoxy composite layer attached to the steel reinforcement to enable continuous structural health monitoring using the EMI technique. The changes in conductance signatures during corrosion progression were quantified through Root Mean Square Deviation (RMSD) indices. The results indicate that RHA and SCBA modified concretes exhibited lower corrosion activity compared to conventional OPC concrete, attributed to enhanced pozzolanic reactions, pore refinement, and reduced chloride ingress. Among the mixtures investigated, 10% of RHA demonstrated the most pronounced improvement in early-stage corrosion resistance, while 20% of SCBA contributed substantially to long-term durability enhancement. The findings confirm the effectiveness of EMI-based monitoring for detecting early corrosion and highlight the potential of agricultural by-products as sustainable SCMs for improving the durability and service life of reinforced concrete structures.