TM 5-623
How to Count:
The number of slabs crossed by the railroad track is counted. Any large pump
created by the tracks should be counted as part of the crossing.
Name of Distress:
Scaling/Map Cracking/Crazing.
Description:
Map cracking or crazing refers to a network of shallow, fine, or hairline cracks
which extend only through the upper surface of the concrete.
The cracks tend to intersect at angles of 120 degrees. Map cracking or crazing is
usually caused by concrete overfinishing, and may lead to surface scaling,
which is the breakdown of the slab surface to a depth of approximately Y4 to 3
inch. Scaling may also be caused by deicing salts, improper construction,
freeze-thaw cycles, and poor aggregate. The type of scaling defined here is
not caused by "D" cracking. If scaling is caused by "D" cracking, it should be
counted under that distress only.
Severity Levels:
L-Crazing or map cracking exists over most of the slab area; the surface is in
good condition, with only minor scaling present (fig B-126).
M-Slab is scaled, but less than 15 percent of the slab is affected (fig B-127).
Figure B-126. Low-severity scaling/map
cracking/crazing.
Figure B-127. Medium-severity scaling/map
cracking/crazing.
H-Slab is scaled over more than 15 percent of its area (figs B-128 through B-
130).
B-44
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