What causes fatigue failure in pavement?

What causes fatigue failure in pavement?

Fatigue cracking is an asphalt pavement distress most often instigated by failure of the surface due to traffic loading. Stripping or raveling is another possible cause of fatigue cracking. Stripping occurs when poor adhesion between asphalt and aggregate allows the aggregate at the surface to dislodge.

What are the causes of distress in pavement?

Possible Causes:

  • Poor joint construction or location. Joints are generally the least dense areas of a pavement.
  • A reflective crack from an underlying layer (not including joint reflection cracking)
  • HMA fatigue (indicates the onset of future fatigue cracking)
  • Top-down cracking.

What are the three main distress modes in asphalt pavement?

In terms of this principle, through the manual inspection, this study identified 12 major distress types of asphalt pavements. These distress types are transverse cracking, rutting, map cracking, pothole, longitudinal cracking, raveling, depression, pumping, bleeding, bump, poor skid resistance, and roughness.

What is fatigue in asphalt pavement?

The fatigue crack on the asphalt concrete pavement occurs when it almost completely lost its tensile strength (tension at bending). The results of the initial tests of the asphalt concrete samples at cyclic bending have been represented in Table 3, and their further test at direct compression—in Figure 13.

What is distress in pavement?

Surface distress is “Any indication of poor or unfavorable pavement performance or signs of impending failure; any unsatisfactory performance of a pavement short of failure” (Highway Research Board, 1970).

What causes fatigue cracking in asphalt?

Fatigue cracking is sometimes called alligator cracking due to the interconnected cracks which resemble an alligator�s skin. Fatigue cracking is caused by load-related deterioration resulting from a weakened base course or subgrade, too little pavement thickness, overloading, or a combination of these factors.

What is pavement failure?

Pavement failure occurs when an asphalt surface no longer holds its original shape and develops material stress which causes issues. Pavement failure issues include cracking, potholes, depressions, rutting, shoving, upheavals, and ravelling.

What are the main stages of fatigue failure?

There are three stages of fatigue fracture: initiation, propagation, and final rupture.

What is asphalt pavement?

Asphalt pavement refers to any paved road surfaced with asphalt. Hot Mix Asphalt (HMA) is a combination of approximately 95% stone, sand, or gravel bound together by asphalt cement, a product of crude oil. The resulting Hot Mix Asphalt is loaded into trucks for transport to the paving site.

What is the cause of road failure?

Other contributing factors such as inadequate drainage system, paucity of maintenance, poor pavement coating of the road, and substandard construction materials are factors leading to a total failure of the road.

What causes fatigue failure?

What causes fatigue failure? Fatigue failure is the formation and propagation of cracks due to a repetitive or cyclic load. Most fatigue failures are caused by cyclic loads significantly below the loads that would result in yielding of the material.

What are the distresses of pavement resurfacing?

If the resulting surface is excessively rough, resurfacing may be necessary (APAI, no date given). Block cracking in a parking lane. Parking lanes see little if any traffic, therefore the only likely distresses that will occur are raveling and block cracking. These cracks are probably too wide to be effectively crack sealed.

When is fatigue cracking a major structural distress?

These cracks are especially significant if they are within the wheel path. Any wheel path longitudinal crack that has associated random cracking is rated as fatigue cracking, which is considered a major structural distress in flexible pavements. See “Fatigue Cracking” on page 5-7 for more information.

What are the signs of a flexible pavement?

Flexible Pavement Primary types of distress associated with flexible pavements are transverse cracking, longitudinal cracking, block cracking, fatigue or 5-4 n s s alligator cracking, rutting, raveling, shoving and flushing.

What causes a small depression in the pavement?

Slight depression in the loading dock area of a hardware store. This is likely due to a localized area of soft subgrade. Depression in an access roadway probably caused by subgrade settlement. Note that the pavement has fatigue cracked significantly as it has settled.

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