Paver asphalt distress manual

NDT is the collective term for evaluations conducted on an existing pavement structure that do not require subsequent maintenance work to return the pavement to its pretesting state.

This is generally desirable to minimize disruption to traffic, and is essential as a screening tool to determine locations where selective material sampling should be conducted to evaluate other material properties in the laboratory. Non-destructive testing methods can assess either functional or structural condition. Material characterization includes:.

Search for the word or phrase:. Help Advanced. A pavement distress investigation involves a thorough review and analysis of existing construction quality control records and tests, and nondestructive testing such as ground penetrating radar GPR , falling weight deflectometer FWD , and dynamic cone penetration testing DCP. These are essential to identify problematic areas and probable causes. Additional field testing, such as portable FWD, dirt seismic pavement analyzer DSPA , coring, trenching, and laboratory testing, may be conducted to confirm the initial hypothesis.

The outcomes from investigations can be used to validate or modify the existing design plan and to resolve the disputes involving construction claims or change orders. Requests for technical assistance are best made as early as possible after becoming aware of the distress to allow opportunity to correct problems if the project is still under construction, prevent further pavement distress, obtain samples of materials actually used on the project for lab testing, and to allow time for appropriate remediation.

Search for the word or phrase:. Possible Causes: Usually caused by traffic action starting and stopping combined with:. Repair: A heavily corrugated or shoved pavement should be investigated to determine the root cause of failure. Repair strategies generally fall into one of two categories:. 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. Description: Localized pavement surface areas with slightly lower elevations than the surrounding pavement. Depressions are very noticeable after a rain when they fill with water. Problem: Roughness, depressions filled with substantial water can cause vehicle hydroplaning.

Possible Causes: Subgrade settlement resulting from inadequate compaction during construction. Repair: By definition, depressions are small localized areas. A pavement depression should be investigated to determine the root cause of failure.

Depressions should be repaired by removing the affected pavement then digging out and replacing the area of poor subgrade. Patch over the repaired subgrade. Joint reflective cracking on a low-use industrial road. Joint reflective cracking on an urban arterial. Description: 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. Possible Causes: Movement of the rigid pavement slab beneath the HMA surface because of thermal and moisture changes. Generally not load initiated, however loading can hasten deterioration. Longitudinal cracking.

The cracking appears to be the onset of alligator fatigue cracking and may be occurring on the longitudinal joints. Longitudinal cracking on a collector street. Usually a type of fatigue cracking. Problem: Allows moisture infiltration, roughness, indicates possible onset of fatigue cracking and structural failure.

Small utility patch on a collector street. Right: Larger Utility patch across an arterial. Notice that the patch edges are separated from the surrounding pavement. These edges need to be crack sealed to prevent water infiltration into the subgrade. Description: 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.

Repair: Patches are themselves a repair action. The pavement on the right uses river rock, which is more susceptible to abrasion, as its aggregate and is showing some signs of aggregate polishing. This close-up picture of a road surface shows aggregate wear after about 5 years of wear. Description: Areas of HMA pavement where the portion of aggregate extending above the asphalt binder is either very small or there are no rough or angular aggregate particles.

Possible Causes: Repeated traffic applications. Generally, as a pavement ages the protruding rough, angular particles become polished. This can occur quicker if the aggregate is susceptible to abrasion. Repair: Apply a skid-resistant slurry seal, BST or non-structural overlay. Pothole forming from a badly fatigued wheelpath area on an arterial.

Notice the water in the pothole even though it has not rained in almost 12 hours. Pothole on a major highway. The area has been repaired but the repair is failing. A more comprehensive effort is needed to correct this pavement failure. Description: Small, bowl-shaped depressions in the pavement surface that penetrate all the way through the HMA layer down to the base course.