UFC 3-260-03
15 Apr 01
table 6-1 or calculated using deflections resulting from ASTM D 1635:
With this hE value, the evaluation is made using the flexural strength of the pavement and the modulus
of subgrade reaction of the material below the stabilized layer.
d. Method of Evaluation. After the existing thickness or equivalent thickness, flexural strength, and
modulus of soil reaction have been determined, the evaluation of a pavement using edge loading criteria
(Army and Air Force) is made from figures 6-1 through 6-18 along with figures 6-19 through 6-36 for
standard evaluations and figures 6-37 through 6-54 for extended life evaluations. Evaluation of a pave-
ment using interior load criteria (Navy and Marine Corps) is made from figures 6-55 to 6-59.
e. Army or Air Force Evaluation Example for Plain Concrete. This example uses an Air Force
group for evaluation, but the procedures are applicable to Army and Air Force. Assume:
(1)
Airfield runway and parking apron having uniform thickness he = 305 millimeters
(12 inches).
Table 6-1
Suggested Es Values for Stabilized Layers (Use as a guide when values are not available.)
Compressive Strength, MPa (psi)
Modulus of Elasticity, MPa (psi)
3.5 - 5.2 (500 - 750)
3,448 (50,000)
5.2 - 6.9 (750 - 1,000)
5,515 (800,000)
6.9 - 10.3 (1,000 - 1,500)
8,275 (1,200,000)
10.3 - 13.8 (1,500 - 2,000)
11,032 (1,600,000)
Over 13.8 (Over 2,000)
13,790 (2,000,000)
(2)
Concrete flexural strength R = 4.8 MPa (700 psi).
(3)
Subgrade modulus of soil reaction k = 81.3 kPa/mm (300 pci).
(4)
Condition of pavement = excellent with adequate load transfer at the joints.
The runway evaluation is based on the thickness of the pavement in the center 23-meter (75-foot) width of
the runway, and the runway is divided into two traffic areas. The first 305 meters (1,000 feet) at the ends
of the runway are type A traffic areas, the runway interior is a type C traffic area, and the parking apron is
a type B traffic area.
(a) Problem 1. Determine the extended life evaluation for Air Force Group Index 14 on
the types A, B, and C traffic areas in terms of the allowable gross weight. The allowable gross weight is
determined as illustrated in the following tabulation:
6-4
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