UFC 3-260-03
15 Apr 01
pavement. The method of evaluating a rigid overlay on flexible pavement is the same as that used for a
plain concrete pavement on a base course.
10. COMPOSITE PAVEMENT.
a. Data Required. The data required for the evaluation of a composite pavement are presented in
chapter 3 and depend, as does the method of evaluation, on the thickness of the nonrigid material
between the two rigid pavements. When the thickness of the nonrigid material is less than 102 milli-
meters (4 inches), the specific data required are equivalent thickness of the combined overlay section,
flexural strength of the rigid overlay, and the k value of the foundation materials beneath the rigid base
pavement. When the thickness of the nonrigid material between the rigid pavements is 102 millimeters
(4 inches) or greater, the specific data required are thickness of the rigid overlay, flexural strength of the
rigid overlay, and the k value on the surface of the nonrigid material beneath the rigid overlay.
(1) In the determination of the k value in a plate-bearing test on the surface of the nonrigid
material between the rigid base and the rigid overlay pavement, the limitations imposed are the same as
those on flexible pavement.
(2) Tests for the determination of the strength of the rigid base pavement are not required;
however, the condition of the rigid base pavement must be known if the evaluation of the composite
pavement is made using equation 6-6 to determine hE . The condition of the base pavement must, of
necessity, be determined from a study of previous design and construction records, previous condition
surveys, and performance records of the pavements. If the rigid overlay pavement contains a minimum
amount of structural defects, it can be assumed that the rigid base pavement has experienced little
breakup since the overlay was placed, and the condition of the base pavement can be rated the same
as it was immediately prior to the overlay.
b. Method of Evaluation. The two methods of evaluating a composite pavement, depending on
the thickness of the nonrigid material between the rigid base pavement and the rigid overlay, are dis-
cussed below.
(1) If the thickness of the nonrigid material between the rigid base pavement and the rigid
overlay is less than 102 millimeters (4 inches), the composite pavement will be evaluated in the same
manner as a rigid overlay on a rigid pavement, with the thickness of the nonrigid material assumed to be
a bond-breaking course. The equivalent thickness of the combined overlay section will be computed
from equation 6-3 for partial bond between the overlay and the base pavement.
(2) If the thickness of the nonrigid material between the rigid base pavement and the rigid
overlay is 101 millimeters (4 inches) or more, the composite pavement is evaluated in the same manner
as a plain concrete pavement, with the nonrigid material and the rigid base pavement, assumed to be a
base course. In the evaluation, the thickness of the rigid overlay and the concrete flexural strength of
the rigid overlay will be used. The k value will be determined by a test performed on the surface of the
existing nonrigid material.
11. FIBROUS REINFORCED CONCRETE PAVEMENTS.
a. Data Required. The data required for the evaluation of fibrous reinforced concrete pavements
as presented in chapter 3 do not differ greatly from that required for plain rigid pavements. Generally,
fibrous reinforced pavements are used for overlays because of the thin sections of pavements that can
be used, and the evaluation would be the same as that outlined for a rigid overlay over rigid pavements
in this chapter. The determination of the flexural strength value of fibrous concrete (ACI 544.2 R) is
6-14
Previous Page
