Determining the microstructure and mechanical properties of reinforcement corrosion products is crucial for understanding the concrete structure durability failure and developing the concrete corrosion-induced cracking model.The reinforcement corrosion products before and after concrete cracking are sampled and analyzed on the basis of a decommissioned bridge in Zhanjiang and an aging wharf in Wenzhou,both exposed to the real marine environment.The chemical composition,microstructure,and volume expansion coefficient of corrosion products are measured by X-ray diffraction (XRD),thermogravimetric analysis (TG),and scanning electron microscopy (SEM).The nanoindentation experiments are carried on to determine the elastic modulus and hardness of the corrosion products.The results indicate that the main components of the reinforcement corrosion products before and after concrete cracking are oxides of iron and oxyhydroxides.The volume expansion coefficients of the corrosion products in different zones,including the splash zone after cracking,the splash zone before cracking,the tidal zone before cracking,and the submerged zone before cracking,gradually decrease,with values of 2.552 2,2.341 4,2.340 5,and 1.990 3,respectively.Furthermore,the average elastic modulus of the reinforcement corrosion products before concrete cracking ranges from 137.06 to 154.70 GPa,while the average hardness ranges from 1.001 to 1.149 GPa.After concrete cracking,the average elastic modulus of corrosion product is 125.89 GPa,and the average hardness of corrosion product is 0.892 4 GPa.