From the chloride ion content profile, the chloride ion diffusion coefficient can be estimated in accordance with ASTM C1556 or NT Build 443 and used for estimating the remaining service life.
A grinding bit, 18 mm in diameter, grinds the concrete to a fine powder at exact depth increments, which can be selected between 0.5 mm to 2.0 mm. The bit is attached to a grinding machine that is held against the surface by a grinding plate. Grinding is accomplished by rotating the grinder within the grinding plate so that the bit removes a circular portion of the surface. The grinding area is 73 mm in diameter and the maximum depth is 40 mm. For horizontal surfaces, the powder produced at each depth increment is collected with a battery-operated vacuum cleaner (Dust Buster) containing a re-usable filter. On a vertical face, the powder at each depth increment is collected in a plastic bag attached to the grinding plate, as shown to the right. For every depth increment of 1 mm, approximately 9 grams of powder is obtained for analysis. It takes 4 to 6 minutes to obtain each sample and about 5 minutes to determine the chloride content using the RCT Kit.
The Profile Grinder can be attached to horizontal and vertical surface using anchor bolts and clamping pliers as shown in the above photographs. In addition a grinding bench plate is available to permit profile grinding of small specimens. These can be specimens molded in the laboratory and used in diffusion testing such as ASTM C1556 of NT Build 443, or cores drilled from the structure.
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