Concrete ships were constructed in both World War I and World War II when steel was in short supply. They were not wildly successful, as they were limited in deadweight and had a tendency to crack. (No concrete ships were built after the end of the wars.) Nevertheless they were extremely durable ships.
The S.S. C. W. Pasley and the S.S. Francois Hennebique, two concrete ships built in Tampa Florida by McCloskey and Company in 1944, have served as the foundations for the docks in Yaquina Bay, in Newport, Oregon for almost sixty years. The S.S. Francois Hennebique is apparently in good shape but the S.S. Pasley is cracking, shifting and oddly, leaking oil. (One might have though that tank cleaning was in order before converting the ship into a dock.) So 66 years after her keel was poured, the S.S. Pasley will be broken up and replaced by a more conventional pier.