Page 310 - Planning and Design of Airports

268 Airp o r t D e sign

Percentage
Finer than 0.02 Soil
Frost Group Kinds of Soils mm by Weight Classification
FG-1 Gravelly soils 3–10 GW, GP, GW-GM,
GP-GM
FG-2 Gravelly soils 10–20 GM, GW-GM,
sands 3–5 GP-GM.
SW, SP, SM,
SW-SM, SP-SM
FG-3 Gravelly soils Over 20 GM, GC
Sands, except Over 15 SM, SC
very fine silty
sands
Clays, PI above – CL, CH
12
FG-4 Very fine silty Over 15 SM
sands
All silts – ML, MH
Clays, PI = 12 – CL, CL-ML
or less
Varved clays – CL, CH, ML, SM
and other fine
grained baded
sediments

TABLE 7-4 Frost Design Soil Classification
in the stability of a soil. The FAA allows for the stabilization and
treatment of the soils to improve the performance of the constructed
pavement. Two types of soil stabilization exist, mechanical stabiliza-
tion and chemical stabilization. Mechanical stabilization consists of
embedding cobble or shot rock sheets within the soil. In some cases,
porous concrete or geosynthetics may be used for very soft fine grained
soils. Chemical stabilization is achieved by the addition of proper per-
centages of cement, lime, fly ash, or combinations of these materials
to the soil.

FAA Pavement Design Methods
Between 1958 and 2006, the FAA established mandates for aircraft
manufacturers to create aircraft, based on their maximum gross take-
off weight and landing gear configuration, that produce loads on
pavements no greater than 350,000 lb, based on the aircraft at the time
that created the heaviest load on airfield pavements, the Douglas DC-8.
As aircraft grew in gross weight, landing gear configurations, with