UFC 3-260-02
30 June 2001
CHAPTER 12
PLAIN CONCRETE PAVEMENTS
1. BASIS OF DESIGN ARMY AND AIR FORCE. The pavement thickness requirement is calculated
using a mechanistic fatigue analysis. Stresses under design aircraft are calculated using the
Westergaard edge-loaded model. These calculated edge stresses are related to the concrete flexural
strength and repetitions of traffic through a field fatigue curve based on full-scale accelerated traffic test
of aircraft loads. A wide variety of model tests, theoretical analyses, and field measurements over the
years have demonstrated that part of the load applied to the edge of a pavement slab is transferred to
and carried by the adjacent slab through dowels, aggregate interlock, etc. For design, a load transfer
value of 25 percent is routinely used as a reasonable approximation of the load transfer measured over
time on the types of joints approved for use in Army and Air Force airfields. The actual load transfer at a
joint will vary depending on joint type, quality of construction, slab length, number of load repetitions,
temperature conditions, etc. The design charts in this chapter were developed based on a 25 percent
load transfer value. If adequate load transfer is not provided at the joints of trafficked slabs, the
pavement should be designed for no load transfer using the PCASE pavement design program that
allows direct input of the load transfer value or the gross load used in the design charts in this chapter
should be increased by 1/3 to remove the load transfer effect. Alternatively, a thickened edge detail can
be used at joints without adequate load transfer. This design method also includes a thickness reduction
for high-strength subgrades (modulus of subgrade reaction, k, > 54 kPa/mm (200 pci) in recognition that
after the initial flexural fatigue crack forms (classical design failure condition for this design method) the
continued slab deterioration through additional cracking and spalling proceeds more slowly on high-
strength subgrades than on low-strength subgrades.
2. BASIS OF DESIGN NAVY. The pavement thickness requirement is calculated using a
mechanistic fatigue analysis. Stresses under design aircraft are calculated using the Westergaard
interior load model for light traffic or training base commands. For medium to heavy loaded pavements,
the Army and Air Force design procedure described above should be considered. The Navy recognizes
edge stress design as a way to reduce pavement life cycle costs for bases with medium to heavy traffic
missions. These calculated interior stresses are related to the concrete flexural strength and repetitions
of traffic through a fatigue curve based on a conservative laboratory beam test relation originally
developed by the Portland Cement Association. Adequate quality joints at short joint spacing are
required to provide load transfer with the Navy assumptions. Alternate thickness design methods are
allowed for Navy pavements if the method is approved by the NAVFAC.
3. USES FOR PLAIN CONCRETE. Military airfield experience has found that plain, unreinforced
concrete is generally the most economical concrete airfield surface to build and maintain. Unreinforced
concrete will be used for concrete military airfield pavements unless special circumstances exist. The
most common exception will be for cases requiring conventional reinforcing as noted in Chapter 1,
paragraph 7 and Chapter 13. Other reinforcing for which design techniques are provided in this manual
are for special circumstances and their use must be approved by TSMCX, AF MAJCOM pavements
engineer, or NAVFAC as appropriate.
4.
THICKNESS DESIGN - ARMY AND AIR FORCE PAVEMENTS.
a. General. Figures 12-1 through 12-22 are design curves to be used in designing plain concrete
pavements as defined in Chapters 2, 3, and 4. Figures 12-1 through 12-5 are for Army Class I to IV
airfields, and Figures 12-6 to 12-17 are for Air Force (Figures 12-6 to 12-11 are for standard mixed traffic
12-1
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