Handbook for Bridge Inspections - TSP2

Any dust should be extracted using an 18 mm. dri ll from four test
hol es per test. The holes should form the corners of a 5X5 em .
Square.
Methods
Figure 7.3-5. Drilling 0111 Cemelll
Dlis/
Equipment
Figure 7.3-6: RCT Allalysis Case
Scope
The choice of method of analysing concrete dust - on site or in a
laboratory - depends fi rst and foremost on how much accuracy is
required and on the costs.
On Site Methods
The most common methods are RCT (Rapid Chloride Test) and
Quantab. Reference is made to the National Public Roads
Administration Handbook No. 015: "On Site Testing", Methods
15.552 and 15.553. These methods are less precise than those used
in a laboratory, but in most cases they will be sufficiently accurate
provided they are checked aga inst reference dust or laboratol)'
methods.
* Equipment fo r test extrac tions (hammer effect drill)
* Plastic bags fo r collecting the dust in
* Felt-tip pens for marking the tests
* Material and eq uipment for refi lling the holes
* Equipment for analysis purposes (on site kit)
* Scales with an accuracy of III 0 grams
* Dust for reference purposes
Laboratory Methods
The most common laboratory methods are potentiometric titration
and Vo lhardt's Method. Laboratory methods must be used whenever
the results of the analyses have to be very precise.
The analysis methods are described in the National Pub lic Roads
Administration Handbook No. 014: "Laboratory Testing", whil st
Volhardt's Method is described in NS 3671.
Acceptance Inspection
So far as large new coastal bridges are concerned routines require
to be established in connection with taking chloride measurements
from selected construction elements. Any incursions of chl oride
should be followed up with repeated measurements during future
main inspections.
Otherwise, measurements of the chl oride content are not taken
during completion inspections.
Major Inspections
If embedded chloride is suspected, for example, because of the
visible results of corrosion, peeling and corroded reinforcement on
the surface concrete, measurements should be taken of the chloride
content.