Handbook for Bridge Inspections - TSP2

Superstructure
Surfaces most exposed
t o Chloride Penetration
Surfaces least exposed
to Chloride Pene tratio n
Chloride and Mo isture
Combination of
Materia ls Testing
Leeward facing surfaces low down and near the water surface,
especially large cross·sections, for example pil lars of Cantil ever
Bridges;also the underneath of bottom plates, cross girders and
beams.
The windward sides of sl im superstructures with a hi gh elevation
above sea· level.
Concrete surfaces containing a high level of chloride will retain
moisture longer during the drying out process and will consequently
be of a darker shade than surfaces with a low salt content.
It is therefore possible in a damp coastal cl imate to see with the
naked eye which surfaces have most been affected by chloride.
Surfaces greatly subject to wind and rain (on the windward side)
will gradually acquire a sandy appearance because the top surface
layer of the concrete will have been washed away.
When deciding the places to undertake materials testing one
should make use of this knowledge of chloride instigated stress.
It is important to carry out several kinds of materials testing, e.g.
surface cover measurements, chloride analyses, ECP measurements,
cutting open the concrete, in such a way that these can be
compared wi th one another before the condition of the concrete is
decided on. Materials testing should also be viewed in relationship
to any visual inspections undertaken.
in order 10 be able to compare the result's of materials testing such
as surface cover and ECP measurements, measuring the chloride
content and the depth of carbonisation, and cutting open the concrete,
they must all be carried out at the same places. Refer to
Chapter 8.5 for a presentation of materials testing for concrete.
7.4 Adequate Materials
Testing - Steel
In the following section a description wi ll be given of the possible
materials testing for use in inspections of bridge sib ridge elements
made of steel.
Purpose
Procedures
7.4.1 Checking the Torque of Screws
To check the stud torque of screws in friction joints.
Checking the torque of screws may be necessary in connection
with acceptance inspections if this has not already been carried out
during the construction phase. Reference is made to the National
Public Roads Admini stration Manual No. ISO: 'Bridges - Safety
and Technical Standards', Point NO.7.