What is Pavement Reconstruction?

Pavement reconstruction is the replacement of the main structural elements of a pavement.

What counts as reconstruction

The FAA defines it in AC 150/5320-6G, section 4.4. The structural element depends on the pavement type.

• Rigid pavement. The panel is the main structural element. Replacing more than 30 percent of the panels is reconstruction.
• Flexible pavement. The sub-base, base, stabilized base and surface course form the pavement structure. Removing and replacing any structural layer below the surface course is reconstruction.

Reconstruction does not always cover the whole pavement or reach the subgrade. The FAA accepts partial reconstruction of only the severely distressed areas, for example the center (keel) sections. Existing base and subbase layers in good condition can stay in place. Full depth reclamation of flexible pavement and rubblization of rigid pavement may replace removal of the existing section. Crack and seat is a third alternative (section 4.9).

Reconstruction and rehabilitation

Rehabilitation is the replacement of a portion of the structural layers. For example, a mill and overlay of a flexible pavement, or the replacement of up to 30 percent of the panels of a rigid pavement. The FAA says rehabilitation is generally more cost effective than reconstruction.

The Pavement Condition Index (PCI) is a survey result from 0 to 100. The FAA gives these guide values in AC 150/5320-6G:

• A PCI between 55 and 70 makes a pavement a candidate for rehabilitation.
• A PCI below 55 makes a pavement a candidate for reconstruction.

The FAA also states that these PCI numbers are relative limits. It says to use them with caution because the PCI shows only the surface condition. A pavement with a PCI above 55 can need reconstruction, and one below 55 can get an overlay, depending on the distresses behind the PCI. The engineer documents the method, timing and extent of the work in the engineer’s report.

Design and causes of failure

Structurally, the design of a reconstruction is the same as the design of a new pavement. When the cause is a structural failure, the design must remove every deficiency that contributed to it. Examples are an improved subgrade, better drainage, or additional structural material (section 4.5.2.2).

The FAA recommends improving the subgrade when its mean strength is below CBR 5 (California Bearing Ratio). Below CBR 3, the subgrade must be stabilized or replaced (section 2.4). The minimum design life of a new pavement on a federally funded project is 20 years. A rehabilitation project has a minimum of 10 years (section 3.11.3).

Cost and operations

AC 150/5380-7B states that preservation treatments cost less in total than reconstruction. It also states that reconstruction projects normally need long closures. Preserving a pavement in good condition costs four to five times less than rehabilitating one in fair to poor condition.

AC 150/5370-10H gives standard specifications for the work. Examples are Item P-101 (Preparation/Removal of Existing Pavements), P-152 (Excavation, Subgrade, and Embankment) and P-154 (Subbase Course). Others are P-209 (Crushed Aggregate Base Course), P-304 (Cement-Treated Aggregate Base Course), P-401 (Asphalt Mix Pavement) and P-501 (Cement Concrete Pavement). The FAA recommends them, but they are not mandatory.

Link to pavement inspection

A reconstruction changes the strength of the pavement. AC 150/5335-5D notes that an overlay or a reconstruction raises the pavement classification rating (PCR) for aircraft with a higher aircraft classification rating (ACR).

The pavement management program (PMP) uses inspection data to choose the time and type of treatment. A federally obligated US airport does a detailed inspection of its pavements at least once a year. A PCI survey per ASTM D5340 can extend that interval to three years (AC 150/5380-7B). A drone survey can supply the distress inventory and the PCI as one input to the decision. It does not decide between rehabilitation and reconstruction, which is an engineering judgment.