TM 5-826-6/AFR 93-5
Figure A-105. Pumping.
(3) Counting procedure. Slabs are counted as indicated in figure A-106. One pumping joint between two slabs
is counted as two slabs However, if the remaining joints around the slab are also pumping, one slab is added per
additional pumping joint.
two slabs counted
three slabs counted
five slabs counted
Figure A-106. Counting procedure for pumping.
z. Scaling, map cracking, and crazing, distress 70.
(1) Description. Map cracking or crazing refers to a network of shallow, fine, or hairline cracks that 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 overfinishing the concrete and may lead to scaling of the surface, which is the breakdown of
the slab surface to a depth of approximately 1/4 to 1/2 inch. Scaling may also be caused by deicing salts, improper
construction, freeze-thaw cycles, and poor aggregate. Another recognized source of distress is the reaction between the
alkalies (Na2O and K20) in some cements and certain minerals in some aggregates. Products formed by the reaction
between the alkalies and aggregate result in expansions that cause a breakdown in the concrete. This generally occurs
throughout the slab and not just at joints where D cracking normally occurs.
(2) Severity levels.
(a) Low severity level (L). Crazing or map cracking exists over most of the slab area. The surface is in
good condition with no scaling (fig. A-107). The low severity level is an indicator that scaling may develop in the future. A
slab should be counted only if in the judgment of the inspector scaling is likely to occur within a few years.
A-60
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