UFC 4-150-07
19 June 2001
ASTM C 876 Standard Test Method for Half-Cell Potentials of
Uncoated Reinforcing Steel in Concrete can be used to determine
the extent of active corrosion and the degree of susceptibility of
corrosion in other areas in the structure. Corrosion can be detected
before visible signs appear. The method detects corrosion by
measuring the electrical potential of the steel. An electrical
connection is made from one side of a voltmeter to an embedded
steel-reinforcing bar that has been exposed. The other side of the
voltmeter is connected to a copper sulfate half-cell, which is then
put in contact with the concrete surface at various locations. The
magnitude and sign of the resulting voltage is an indication of
corrosion activity.
Ultrasonic methods are available to inspect concrete for voids that
cannot be seen, such as honeycomb pockets, and for internal
deterioration by cracking. Pulse velocities and fundamental
frequencies are imposed in the concrete structure to search for
imperfections. Sonic methods conducted at specific time intervals
can monitor progressive deterioration. Interpretation of data is a
highly specialized skill.
Before starting any of the above tests, a test plan must be prepared
and the areas to be tested must be cleaned thoroughly.
5-6
INSPECTION OF STEEL STRUCTURES
5-6.1
Scoping the Problem. There are six major types of steel structure
deterioration to watch for in the marine environment:
Corrosion
Abrasion
Loosening of structural connections
Fatigue
Overloading
Loss of foundation material
The causes and forms of steel deterioration are described in detail in
Chapter 3.
5-6.2
Surface Inspections. Generally, visual inspections will detect most
forms of deterioration of steel structures. Use Figure 5-16 "Inspection of Steel
Structures (Above Water) Checklist" to ensure a thorough inspection of steel
structures above water is done. In the event that more detailed NDT techniques
5-30
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