3.3.6 Rapid Chloride Permeability (RCP) Test
The specimens for RCP testing of the concrete were conditioned as specified in
AASHTO T277. Two slices, each with a thickness of 50 mm, were cut from the
102x203 mm cylinders or cores, and their circumferences were coated with fiberglass
and resin. After an hour of air drying, they were kept under vacuum (pressure < 1 mm
Hg) for 3 hours, 1 hour more under vacuum with the specimens in de-aerated water, and
then left for 18 hours soaking in water at the atmospheric pressure. After this
conditioning, the specimens were placed in the testing cells. The testing consisted of
monitoring the amount of electrical current passed through the specimen, when a
potential difference of 60 V DC is maintained across the specimen for a period of 6
hours. In this test, chloride ions are forced to migrate out of NaCl solution subjected to a
negative charge, through the concrete, into a NaOH solution maintained at a positive
potential. The total charge passed, in columns, is used as an indicator of the resistance
of the concrete to the penetration of chloride ions