Pavement Management

Flexible Pavement Distress

An introduction to common forms of distress in flexible pavements.

Potholes

Description 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 surfaces (25 to 50 mm (1 to 2 … Read more »

Transverse Screed Marks

Description Transverse indentations in the mat surface across the width of the mat. These indentations occur when the paver stops between truckloads of HMA and the screed rests on the hot mat. Problem Generally, transverse screed marks will not affect a pavement’s structure but they will affect roughness. Possible Causes Causes can be related to … Read more »

Roller Marks

Description Indentations that remain in the mat surface after rolling operations are complete. Most roller marks are removed from the mat surface by finish rolling. Problem Roller marks may cause an increase in roughness, but by themselves they are not particularly damaging to pavement performance. Roller marks are, however, an indication of inadequate compaction and/or … Read more »

Joint Problems

Description Bumps, elevation differences, a lack of mix or low density near or in a transverse or longitudinal joint. Problem Typically, poor transverse joints result in a slight bump, which can affect roughness. Poor longitudinal joints are generally lower in density, may fail prematurely from raveling or cracking, and may allow water infiltration into the … Read more »

Fat Spots

Description Isolated areas in the mat where excess asphalt binder is visible on the surface. Problem A few scattered fat spots may not significantly affect mat durability or pavement structure. A large number of fat spots may affect: Pavement performance. Air voids in fat spot locations may be excessively low leading to potential shoving and … Read more »

Water Bleeding and Pumping

Description 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 under moving loads. Problem Decreased skid resistance, an indication of high pavement porosity … Read more »

Transverse Cracking

Description Cracks perpendicular to the pavement’s centerline or laydown direction. Usually a type of thermal cracking. Problem Allows moisture infiltration, roughness Possible Causes Several including: Shrinkage of the HMA surface due to low temperatures or asphalt binder hardening Reflective crack caused by cracks beneath the surface HMA layer top-down cracking Repair Strategies depend upon the … Read more »

Slippage Cracking

Description Crescent or half-moon shaped cracks generally having two ends pointed into the direction of traffic. Problem Allows moisture infiltration, roughness Possible Causes Braking or turning wheels cause the pavement surface to slide and deform. The resulting sliding and deformation is caused by a low-strength surface mix or poor bonding between the surface HMA layer … Read more »

Reflection Cracking

Description Cracks in a flexible overlay over an existing crack or joint. The cracks occur directly over the underlying cracks or joints. “Joint reflection cracking” specifically refers to reflection cracks arising from underlying PCC pavement joint movement. Reflection cracks can also occur over existing HMA pavement cracks, cement or lime stabilized base, etc. Problem Allows … Read more »

Corrugation and Shoving

Description 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 abuts a rigid object (shoving). Problem Roughness Possible Causes Usually caused by traffic action … Read more »

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