in 1968 and 1969, had 254 mm of PCC over 229 mm
was a heavy clay (USC classificationCL; FAA clas-
of crushed stone base over subgrade. Later construc-
sificationE7) with a design California Bearing Ratio
tion mostly used 305 mm of PCC over 229 mm of
(CBR) of 4. They also reported clay migration into the
crushed stone base over subgrade. The structure of the
base course and trapped water under the pavement.
different pavement sections as of spring 1986 is also
The airport pavements consist of two intersecting
shown in Figure 2.
runways, five taxiways and three ramps (Fig. 3). Run-
The slabs sizes were primarily 7.6 by 7.6 m; how-
way 3/21 was constructed in 1967 and 1968, with 203
ever, in some areas, the slabs were 3.8 by 3.8 m. Other
mm of PCC (254 mm in critical areas) over 203 mm of
sizes used are shown in Table 1. Loads are transferred
crushed gravel over subgrade. Runway 11/29, recon-
across the transverse joints by dowels and aggregate
structed in 1988 and 1989, had 178 mm PCC (229 mm
interlocks (Table 1) (CMT 1984). At longitudinal
in critical areas) over 203 mm of crushed aggregate
joints, loads are transferred through keyways, aggre-
base course over subgrade.
gate interlocks and tiebars (Table 1) (CMT 1984). The
The PCC slabs were mostly 3.8 m wide by 6.1 m
primary types of aircraft using the airport are Convair
long; but, in some areas, the slabs were 3.8 m wide by
580 (24,766 kg), MD DC-9 (44,452 kg) and Boeing
5.3 m long. A typical transverse joint used aggregate
interlocks and dowels for load transfer.* Across longi-
757 (115,666 kg) (CMT 1984).
Outagamie County Airport
200 mm Gravel
178 mm PCC
203 mm Gravel
203 mm PCC
200 mm Gravel
229 mm PCC
203 mm Gravel
254 mm PCC
Figure 3. Pavement structure at Outagamie County Airport (OCA).
tudinal joints, keyways, aggregate interlocks and tie-
Outagamie County Airport (OCA)
OCA is located near Appleton, Wisconsin (Fig. 1).
bars were used for load transfer (ERES Consultants
1985, Mead and Hunt 1988). Richardson stated that
The subgrade at the airport consists mostly of a low
on the basis of a pavement evaluation done prior to
plasticity clay (CL), some sand (SP) and silty sand
1986, the gross allowable aircraft weights on runway
(SM). At OCA, bedrock was estimated to be 4.0 m
11/29 were 27,200-kg single, 40,800-kg dual and
deep or more, on the basis of boring logs. ERES con-
74,860-kg dual tandem. On runway 3/21, the gross al-
sultants (1985) reported the subgrade under runway
lowable aircraft weights were 38,570-kg single,
3/21 as a highly frost-susceptible red silty clay. They
81,670-kg dual and 95,280-kg dual tandem.
also reported that the subbase material may be frost-
susceptible because of a high amount of fines passing
the no. 200 sieve (810 %). Runway 3/21 has severe
frost heave problems (ERES 1985). Mead and Hunt
* Personal Communication, with K. Richardson, Wisconsin De-
(1988) reported that the subgrade under runway 11/29
partment of Transportation, 1991.