A gravity block wharf of a seaport in Africa was built in 1928 and expanded in 1950.During the restoration in 1968,the concrete breast wall was removed and reinforced concrete was rebuilt.Nearly a century since its establishment,the structure has suffered severe damage.According to the survey report,the characteristics of concrete in different periods are revealed,the strength,porosity,crack degree and other characteristics of concrete structure in different periods are described.The reasons for this are analyzed,including the level of concrete technology during construction,the degree of specialization and mechanization in construction,environmental conditions of the wharf,service life and operational status,the setting of wharf protective facilities,as well as the historical background during the operation.Among them,the development level of concrete,selection of raw materials and quality of pouring during the construction are fundamental reasons that affect the performance of concrete in the old wharf,while the main reason is long-term corrosion in high acid and high salt seawater environments.By analyzing the characteristics of concrete,this study provides a basis for the determination of repair plans and the smooth implementation of repair work,and provides references for similar wharf renovation projects.