18-03-2014, 04:45 PM
Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration1
Standard Test Method for Electrical.pdf (Size: 117.34 KB / Downloads: 86)
Scope
This test method covers the determination of the elec-
trical conductance of concrete to provide a rapid indication of
its resistance to the penetration of chloride ions. This test
method is applicable to types of concrete where correlations
have been established between this test procedure and long-
term chloride ponding procedures such as those described in
AASHTO T 259. Examples of such correlations are discussed
in Refs 1-5.2
Summary of Test Method
This test method consists of monitoring the amount of
electrical current passed through 2-in. (51-mm) thick slices of
4-in. (102-mm) nominal diameter cores or cylinders during a
6-h period. A potential difference of 60 V dc is maintained
across the ends of the specimen, one of which is immersed in
a sodium chloride solution, the other in a sodium hydroxide
solution. The total charge passed, in coulombs, has been found
to be related to the resistance of the specimen to chloride ion
penetration.
Significance and Use
This test method covers the laboratory evaluation of the
electrical conductance of concrete samples to provide a rapid
indication of their resistance to chloride ion penetration. In
most cases the electrical conductance results have shown good
correlation with chloride ponding tests, such as AASHTO
T259, on companion slabs cast from the same concrete
mixtures (Refs 1-5).
Interferences
This test method can produce misleading results when
calcium nitrite has been admixed into a concrete. The results
from this test on some such concretes indicate higher coulomb
values, that is, lower resistance to chloride ion penetration,
than from tests on identical concrete mixtures (controls)
without calcium nitrite. However, long-term chloride ponding
tests indicate the concretes with calcium nitrite were at least as
resistant to chloride ion penetration as the control mixtures.