Define Concrete substruct - underwater inspection of bridges?

Plain, reinforced, and pre-stressed concrete are used for construction of underwater elements. Since the majority of substructures are basically compressive units, concrete is nearly ideal material choice as concrete is relatively strong under compressive loading and with steel reinforcing can resist bending and tensile forces. The performance of a concrete structure is most affected by the care taken in its construction and installation. Properly made concrete is highly durable in marine environment.

However, due to faulty construction, poor concrete, continuous weathering, and attack of water coming in contact with the structure, concrete may get damaged over a period of time. Some concrete damage tends to occur as surface damage, which does not jeopardise the integrity of the system. However, concrete deterioration that involves corrosion of the reinforcement can be very serious. There are two principles for deterioration of concrete - physical and chemical.