What is ASTM D6433?

Definition

ASTM D6433 is a standard practice for roads and parking lots. Its title is Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys. The scope covers the determination of pavement condition through visual surveys that use the Pavement Condition Index (PCI) method. The current edition is D6433-24.

The US Army Corps of Engineers developed the PCI for airfield pavements in the 1970s. The version for roads and parking lots became an ASTM standard in 1999.

What the PCI is

The PCI is a number from 0 to 100. A value of 0 means a failed pavement, and 100 means a pavement in excellent condition. It comes from the type, severity and quantity of the distress that an inspector sees. The FAA describes it as an indicator of the structural integrity and the surface operational condition of a pavement.

The FAA airfield scale in AC 150/5380-7B divides the range into seven categories. Secondary sources list the same ranges for ASTM D6433.

How a survey works

The inspector divides a road network into sections, and each section into sample units. For concrete pavement, a sample unit is 20 contiguous slabs, plus or minus 8 slabs. The inspector walks each sample unit and records every distress. Each record has three parts:

• the distress type
• the severity, which is low, medium or high
• the quantity

The inspector measures most asphalt distresses in area or in length and counts potholes. For concrete, the inspector counts the slabs that show each distress. A few distresses have no severity rating: polished aggregate and, for concrete, popouts, pumping and shrinkage cracks.

Each record gives a deduct value, which the standard reads from curves. The standard converts the deduct values to a corrected deduct value. The PCI of the sample unit is 100 minus that value.

Distress types

A training guide drawn from D6433-24 lists 20 asphalt distress types:

• cracking: alligator, block, edge, joint reflection, slippage, longitudinal and transverse
• surface: bleeding, polished aggregate, raveling, weathering
• deformation: bumps and sags, corrugation, depression, rutting, shoving, swell
• other: lane and shoulder drop-off, patching and utility cuts, potholes, railroad crossing

The same guide lists 19 concrete distress types. They include corner break, faulting, joint seal damage, punchout, pumping and spalling at joints and corners.

D6433 and airfield pavement

An airport pavement follows ASTM D5340, not D6433. The FAA names both standards in AC 150/5380-7B, Appendix B, and assigns each to its own type of pavement.

TarmacView’s airfield pavement service uses D5340. A PCI from drone images follows D6433 only if the survey meets the procedure of the standard. That procedure is a visual survey of sample units. TarmacView’s road service does not produce a D6433 PCI.