Handbook for Bridge Inspections - TSP2

Declining Course of
Development
Steady Pace of Development
Accelerating Pace of
Development
This can be exempli fied by settlement whi ch usually develops
quickly at the start and then later begins to decline. Nevertheless
one should be aware that settl ement can demonstrate both a steady
and an accelerating course of development.
Rutting can act as an example here. Its development wi ll usuall y
be linear, but an increase in wear and tear must be reckoned with
when the ruts become deeper because traffic impact wi ll be more
concentrated.
Examples of this kind of damage are insufficient surface
cover/damaged cover, secondary damage such as reinforcement
corros ion or spal1ing. Since the cover has become carboni sed or
infected with chlorides, the corrosion process wi ll start in the reinforcement
clements with least cover with the consequent development
ofspal1ing in the area of these steel elements. As the extent
of the carbon isation or the effects of the chlorides penetrate deeper
into the concrete, so the speed of corrosion development in the
already corroded reinforcement elements wi ll increase, and the
corrosion wi ll spread to new reinforcement. As a consequence
both corrosion in the reinforcement and flak ing will demonstrate
an increasing trend.
Inspection
I
InspeCtion
I
Time I
to Concrete J
== I
I
I
SetUemenl
I
I
o
CotliSion
I
I I J Critical ConOition
----,- --~------
I
I
L -1_ - - - - - - , ____ _
Figure 5.4-1: The Development o/Damage
5.4.3 Compound Damage
Damage to bridges is often composed of severa l types of damage.
Corrosion of reinforcement elements often occurs together with
spalling and insufficient/damaged cover.