Figure 13-29.-Field identification of unknown bituminous materials.
Advantages and disadvantages of the bituminous
are very temperature-susceptible, having a wide range
materials used in construction are discussed.
in viscosity with normal ambient temperature changes.
Asphalt cement cutbacks are flammable. Also, all
Tar can become so soft during warmer weather that the
asphalts can be dissolved by petroleum products that
pavement will rut under traffic. In colder weather it can
become so brittle that the pavement will crack.
may be spilled on them, such as during refueling at an
airfield. Tars, on the other hand, are not affected by
Asphalt emulsions are not flammable and are liquid
petroleum derivatives since they are products of coal.
at normal temperatures. Since they are mixed with
Tars, when used as a prime for base courses, also seem
water, they can be used with a damper
to possess better penetration qualities than asphalts. Tars
required for the cutbacks. Additional
aggregate than
water may be
13-40
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