UFC 3-260-02
30 June 2001
CHAPTER 18
RIGID PAVEMENT INLAY DESIGN
1. GENERAL. Many existing airfield pavement facilities have developed severe distress because
the design life or the load-carrying capacity of the facilities has been exceeded. The distress
normally occurs first in the center lanes of the runways and taxiways because of the concentration
of traffic. A method commonly used to rehabilitate these distressed facilities is to construct an
adequately designed rigid pavement inlay section in the center of the facility. These inlays are
generally 15 meters (50 feet) wide for taxiways and 23 meters (75 feet) wide for runways;
however, the widths will be influenced by the lateral traffic distribution and, in existing rigid
pavements, by the joint configuration. The inlay pavement may consist of plain concrete or
reinforced concrete. The thickness design of the rigid inlay will be the same as outlined in
Chapters 12 through 16 or 19, except for the special requirements presented herein.
2.
RIGID INLAYS IN EXISTING FLEXIBLE PAVEMENT.
a. Figure 18-1 shows a section of a typical rigid pavement inlay in an existing flexible
pavement.
b. Removal of the existing flexible pavement will be held to the absolute minimum. The depth
of the excavation will not exceed the design thickness of rigid inlay pavement. The width of
excavation of the existing pavement will not exceed the required width of the inlay section plus the
minimum necessary, approximately 1 meter (3 feet), for forming or slipforming the edges of the
concrete pavement (Figure 18-1).
c. Subdrains and drainage layers will be considered only when they are essential to the
construction of the inlay section or necessary for proper drainage. When required, the subdrains
will be placed outside of the edge of the rigid inlay and at least 100 millimeters (4 inches) below
the bottom of the inlay pavement to permit construction of the stabilized layer required in the
following paragraph.
d. Unless the material in the bottom of the excavation is granular and free-draining or the
airfield is located in a arid climate, the bottom full width of the excavation will be scarified to a
minimum depth of 150 millimeters (6 inches), and recompacted to the density requirements for the
top 150 millimeters (6 inches) of base course or subgrade as specified previously. This type of
overlay may trap water, and satisfactory drainage must be provided. Reference should be made to
TM 5-822-14/AFJMAN 32-1019 for selection of stabilizing agent and minimum strength
requirements.
e. The modulus of soil reaction k used for the design of the rigid pavement inlay will be
determined on the surface of the material at the bottom of the excavation prior to stabilization. If
stabilization is used and if the strength of the stabilized material does not meet the requirements in
TM 5-822-14/AFJMAN 32-1019 for pavement thickness reduction, no structural credit will be
given to the stabilized material in the design of the rigid pavement inlay. If the strength of the
stabilized layer meets the minimum strength requirement for pavement thickness reduction in
TM 5-822-14/AFJMAN 32-1019, the rigid pavement inlay will be designed in accordance with
applicable sections of Chapters 12 through 16 pertaining to the use of stabilized soil layers.
18-1
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