Reinforced and prestressed concrete in maritime structures

The development of reinforced and prestressed concrete in maritime works is reviewed from its first such use in 1896 until the massive North Sea oil platforms of the 1970s and major projects overseas. The review is divided into broad peiods, including the early applications up to 1920, the extensive developments in the 1920s and 1930s, the Second World War and the period of post-war reconstruction accompanied by the increasing size of maritime facilities at home and overseas. Exposure conditions for most maritime works are exceptionally severe. Reinforced concrete was applied to maritime works at the earliest opportunity and became economically more attractive and structurally more necessary as the dimensions of vessels steadily increased. Consequently, the maritime environment has served as an accelerated test bed for the performance of materials and construction details. The purpose of this paper is to provide background information into what may lie under the surface of existing reinforced structures. For this reason, more details are given of earlier structures than later ones, which should be better recorded and better understood. Reference is made to the continuing studies into the long-term performance of reinforced concrete in sea water, as conducted by the Institution of Civil Engineers and other bodies from the early 1900s, whence it is seen that the same questions have been raised at regular intervals. It is concluded that the ruling mechanisms for the durability of concrete in sea water are, perhaps, now at last being developed into more reliable models.