UFC 3-260-03
15 Apr 01
(2) No set method has been established for reducing the allowable loading for conditions such
as those outlined above. Nonrigid overlays not meeting design requirements might be susceptible to
rutting or raveling. If it can be determined that inadequate load transfer conditions exist at the joints, a
reduction of up to 25 percent in the allowable load could be justified. When a PCI survey results in
ratings of very poor or failed due primarily to structural cracking, the pavement is assumed to have inad-
equate load transfer. Any reduction in the allowable loading will be a matter of judgment, and the engi-
neer must explore all possible sources of information consistent with the job conditions and perform
such tests as are feasible to obtain factual data useful in determining the amount of reduction necessary.
5. PLAIN CONCRETE PAVEMENTS. Plain concrete pavements may be evaluated using stresses
due to load at the edge of a slab (used by the Army and Air Force) or stresses due to load at the interior
of a slab (used by the Navy and Marine Corps).
a. Edge Loading Condition. When using the edge loading condition, there are two basic evalu-
ation criteria for plain concrete pavements. These two criteria are the standard evaluation and the
extended life evaluation. Army airfield pass/load relationships are to be reported for both criteria.
Air Force evaluations are to be reported using the extended life criteria.
(1) Standard Evaluation. The standard evaluation criteria are essentially the reverse of
design and are based upon a criteria where 50 percent of the slabs are cracked into two or three pieces
at the end of traffic (sometimes referred to as initial failure or first crack failure).
(2) Extended Life Evaluation. The extended life evaluation is based upon a criterion where
50 percent of the slabs are cracked into approximately six pieces at the end of traffic (sometimes refer-
red to as shattered slab failure).
b. Interior Load Condition. The interior load condition consists of only one criterion that is used as
the basis of Navy and Marine Corps evaluations.
c. Data Required. The data required for evaluation of plain concrete pavements are presented in
chapter 3. In addition, if the pavement structure contains a stabilized layer, it will be necessary to obtain
the modulus of elasticity and thickness of the stabilized layer. The stabilized layer is considered as a
low-strength base pavement, and the following equation will be used to determine an equivalent thick-
ness of the combined pavement:
1.4
Es
1.4
3
(eq 6-1)
(he)1.4 %
hE '
hs
Ec
where
hE = thickness of plain concrete equivalent to the combined pavement and stabilized layer
thickness, millimeters (inches)
he = thickness of concrete pavement, millimeters (inches)
hs = thickness of stabilized layer, millimeters (inches)
6-3
Previous Page
