Monitoring chloride-induced corrosion in cementitious materials using quantitative ultrasound imaging: from mechanical property alteration to crack propagation

Recent advancements in the quantitative ultrasound (QUS) technique have shown its efficiency in characterizing cementitious materials, providing better resolution than conventional B-mode imaging for visualizing internal structures. This paper leverages the advantages of QUS to assess chloride-induced corrosion in reinforced mortars. Unlike conventional B-mode imaging methods, QUS offers a quantitative parameter, spectral slope (SS), which is crucial for corrosion monitoring owing to its high sensitivity to microstructural changes. Utilizing a 1 MHz phased array transducer, this research focuses on measuring SS to spatially map the distributions of material degradation and cracking caused by the corrosion process. Complementary measurements, including electrochemical impedance, corrosion potential, and crack visualization, are employed to understand the formation of corrosion products comprehensively. The results affirm the effectiveness of QUS in quantitatively assessing the corrosion process, from monitoring material degradation to tracking crack propagation, highlighting its potential as a nondestructive tool for early-stage corrosion detection in civil infrastructure.