Civil Engineering Reference
In-Depth Information
100
10
3.7
3.9
4.1
4.3
4.5
4.7
4.9
UPV km/s
Equivalent cube strength N/mm2
Expon. (Equivalent cube strength N/mm2)
1.
Chloride content
4.
Sulfate content
2.
Cement content
5.
Type of cement
3.
Depth of carbonation
6.
Alkali content
In the following, an explanation of the reason why each parameter is
important is given, followed by an explanation of the test itself.
Chloride content test methods
The generally accepted method of test for chloride in hardened concrete
is described in BS 1881 : Part 124: 1988 (BSI, 1988). The test involves
crushing a sample of the concrete to a fine dust, extracting the chloride
with hot dilute nitric acid and then adding silver nitrate solution to
precipitate any chloride present. Ammonium thiocyanate solution is then
titrated against the remaining silver and the amount of chloride determined
from the difference between the added silver nitrate and that remaining
after precipitating the chloride. Faster and more precise methods based on
ion-selective electrodes are now available. One of the more modern
automated analysers is illustrated in
Figure 1.24.
Automated testing is
