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Typical failures of flexible pavement

Short answer

Typical flexible pavement failures: alligator cracking from repeated loading, rutting from weak subgrade, potholes from water entry, ravelling from binder loss, bleeding from excess binder, shoving from unstable mix, and edge failure from poor shoulder support. Each requires specific repair like patching, sealing, or overlay.

Explain the typical failures of flexible pavement with neat sketches?

Typical failures of flexible pavement

A flexible pavement fails when it can no longer give a safe, smooth ride or carry traffic. Common failures:

FailureDescriptionMain causesRemedy
Alligator (fatigue) crackingInterconnected cracks like a crocodile skin in wheel pathsRepeated loading, thin layers, weak subgrade or base, poor drainage, aged binderPatching or removal and replacement, overlay, drainage improvement
RuttingLongitudinal depressions in wheel pathsWeak subgrade/base, insufficient compaction, overloading, soft mix in heatFill with levelling course, overlay, reconstruct if deep
Shoving and corrugationWaves across the roadUnstable mix, poor bond, braking and starting loadsRemove and replace, scarify and relay
PotholesBowl-shaped holesWater entry in cracks, weak mix, traffic wearPatching with premix
RavellingLoss of stone from the surfacePoor bitumen, stripping, age, insufficient binderSeal coat, surface dressing
BleedingExcess bitumen forms a shiny filmToo much binder, low air voids, heatHot sand/chips, remove binder
Depression and settlementLocal sinkingSubgrade consolidation, poor compaction, utility trenchFill and level, reconstruct base
Edge failureBreaking at pavement edgePoor support, narrow shoulder, waterStrengthen shoulder, drain
Longitudinal / reflection cracksCracks following joints belowDifferential settlement, poor construction joints, old cracksSeal, overlay with crack relief layer
StrippingLoss of bond between bitumen and aggregateWater action, hydrophilic aggregateAnti-stripping agent, replacement
 Alligator cracking      Rutting (cross-section)
 +--+--+--+--+
 |x |x |x |x |   ----.         .----
 +--+--+--+--+        '-------'
 small interlocked    depressed wheel path
 cracks

✓ Answer checked by Claude Opus 5.5 (high effort)

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