Surface Distresses

The answers to the question “Why Asphalt” are numerous and varied.  For those of you that would like to explore the top reasons for why asphalt pavements constitute the vast majority of paved roads in America, we’re created this short summary document:

THE MANY BENEFITS OF ASPHALT

Water Bleeding and Pumping

Water bleeding (left two photos) occurs when water seeps out of joints or cracks or through an excessively porous HMA layer.  Pumping (right-most photo) occurs when water and fine material is ejected from underlying layers through cracks in the HMA layer or out the...

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Transverse (Thermal) Cracking

Transverse cracks are cracks perpendicular to the pavement's centerline or laydown direction and are usually a type of thermal cracking caused by temperature fluctuations. A large transverse crack caused by the pavement's contraction in cold weather.  The crack has...

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Stripping

The loss of bond between aggregates and asphalt binder that typically begins at the bottom of the HMA layer and progresses upward.  When stripping begins at the surface and progresses downward it is usually called raveling. A small pavement core showing stripping at...

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Slippage Cracking

Crescent or half-moon shaped cracks generally having two ends pointed into the direction of traffic. Slippage crack at an intersection due to stopping.  The direction of traffic is from top to bottom.  Most likely caused by poor bonding with the underlying pavement –...

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Rutting

Pavement rutting is defined as a surface depression in the wheelpath.  Pavement uplift (shearing) may occur along the sides of the rut.  Ruts are particularly evident after a rain when they are filled with water.  There are two basic types of rutting: mix rutting and...

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Raveling

The progressive disintegration of an HMA layer from the surface downward as a result of the dislodgement of aggregate particles. Raveling possibly resulting from segregation, temperature differentials or inadequate compaction. Raveling that is likely the result of...

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Potholes

Small, bowl-shaped depressions in the pavement surface that penetrate all the way through the HMA layer down to the base course.  They generally have sharp edges and vertical sides near the top of the hole.  Potholes are most likely to occur on roads with thin HMA...

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Polished Aggregate

Polished aggregate is typically due to aggregates that are softer and aren't resistant to abrasion. River rock is more susceptible to abrasion, especially compared to a quarry or basalt material.  This close-up picture of a road surface shows aggregate wear after...

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Patching

An area of pavement that has been replaced with new material to repair the existing pavement.  A patch is considered a defect no matter how well it performs. Two patches on an urban arterial placed after utility cuts. A patch on an urban arterial used to repair a...

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Longitudinal Cracking

Cracks parallel to the pavement's centerline or laydown direction.  Usually a type of fatigue cracking. Longitudinal cracking on a city arterial.  Its location in the wheelpath indicates that is probably the onset of fatigue cracking. Longitudinal cracking on a rural...

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Joint Reflection Cracking

Cracks in a flexible overlay of a rigid pavement.  The cracks occur directly over the underlying rigid pavement joints.  Joint reflection cracking does not include reflection cracks that occur away from an underlying joint or from any other type of base (e.g., cement...

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Depression

Localized pavement surface areas with slightly lower elevations than the surrounding pavement.  Depressions are very noticeable after a rain when they fill with water. Depression in an access roadway probably caused by subgrade settlement.  Note that the pavement has...

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Corrugation and Shoving

A form of plastic movement typified by ripples (corrugation) or an abrupt wave (shoving) across the pavement surface. The distortion is perpendicular to the traffic direction. Usually occurs at points where traffic starts and stops (corrugation) or areas where HMA...

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Block Cracking

Interconnected cracks that divide the pavement up into rectangular pieces.  Blocks range in size from approximately 1 ft2 to 100 ft2.  Larger blocks are generally classified as longitudinal and transverse cracking.  Block cracking normally occurs over a large portion...

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Bleeding

A film of asphalt binder on the pavement surface.  It usually creates a shiny, glass-like reflecting surface that can become sticky when dry and slippery when wet. Classic bleeding on a newly paved road shows up as a shiny reflecting surface - especially in the...

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Alligator (Fatigue) Cracking

A series of interconnected cracks caused by fatigue failure of the HMA surface under repeated traffic loading.  As the number and magnitude of loads becomes too great, longitudinal cracks begin to form (usually in the wheelpaths).  After repeated loading, these...

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