A blowup usually occurs at a transverse crack or joint. At a crack, it is counted as being in one slab, but at a joint, two slabs are affected and the distress should be recorded as occurring in two slabs.
Record blowup on a slab only if the distress is evident on that slab. Severity may be different on adjacent slabs. If blowup has been repaired by patching, establish severity by determining the difference in elevation between the two slabs.
At the present time, no significant research has been conducted to quantify severity levels for blowups. Future research may provide measurement guidelines:
|
Severity Level |
Difference in Elevation | |
|
Runways and High-speed Taxiways |
Aprons and Other Taxiways | |
|
L |
<1/2 in. (<13 mm) |
¼ to 1 in. (6 to 25 mm) |
|
M |
½ to 1 in. (13 to 25 mm) |
1 to 2 in. (25 to 51 mm) |
|
H |
Inoperable |
inoperable |