TM 5-623
How to Measure:
Block cracking is measured in square feet of surface area. It usually occurs at one
severity level in a given pattern section; however, any areas of the pavement
section having a distinctly different level of severity should be measured and
recorded separately.
Name of Distress:
Bumps and Sags.
Description:
Bumps are small, localized, upward displacements of the pavement surface. They are
different form shoves in that shoves are caused by unstable pavement. Bumps,
on the other hand, can be caused by several factors, including-
1.
Buckling or bulging of underlying Portland cement concrete (PCC) slabs in asphalt
concrete (AC) overlay over PCC pavement.
2.
Frost heave (ice, lens growth).
3.
Infiltration and buildup of material in a crack in combination with traffic loading
(sometimes called tenting).
Sags are small, abrupt, downward displacements of the pavement surface.
Distortion and displacement which occurs over large areas of the pavement surface,
causing large and/or long dips in the pavement is called swelling.
Severity Levels:
L-Bump or sag causes low-severity ride quality (fig B-15).
Figure B-15. Low-severity bumps and sags.
M-Bump or sag causes medium-severity ride quality (figs B-16, B-17, and B-18).
Figure B-17. Medium-severity bumps and sags.
Figure B-16. Medium-severity bumps and sags.
B-7
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