A floating concrete dock is not a new concept. However, a few years ago, a structural floating dock system combining the durability of a concrete deck surface with the structural strength of a large concrete section was introduced. The precast Trus-Channel dock system is capable of withstanding significant marine loads. The system consists of concrete placed around three sides of a foam block. The structural strength of the section is significant in both vertical and lateral loading directions for either negative or positive movements and shears. The entire system rides on vertical piles to accommodate tides.
The most important design criteria is that the system floats. Specified freeboards range from 12 to 17 inches. To accurately design for freeboard, the weights of all materials must be determined with precision. The design should consider lateral, vertical, dead, and live loads, as well as vessel impact loads.
Most of the float installations have been in salt water, which has the advantage of being slightly more buoyant. This is offset, however by the disadvantage of chloride corrosion. Mix specification requirements typically include a corrosion inhibiting admixture with calcium nitrite. Floats are cast in steel forms with a smooth, true surface. Special procedures are required to ensure that the foam core does not move during concrete placement and consolidation. The top deck is steel troweled with a light broom finish applied transversely to the walking surfaces.