Figure 4-48. Single-shaft rotary mixer with
asphalt supply tank.
Figure 4-50. Mixing with motor grader.
Figure 4-49. Single-shaft rotary mixer without asphalt.
(c) Motor graders. Blade mixing is the on-
site mixing of asphalt and in-place materials on
the roadbed by a motor grader (fig 4-50). The
asphalt is applied directly ahead of the motor
Figure 4-51. Distributor applying asphalt.
grader by an asphalt distributor. For most effec-
tive blade mixing, the motor grader should have a
at controlled rates to as high as 3 gallons per
blade at least 10 feet long, and should have a
square yard. It is important to keep an adequate
wheelbase of at least 15 feet. Motor graders used
supply of asphalt at or near the jobsite to avoid
for final layout and finishing of the surface should
delays. In rural areas, it may be advisable to have
be equipped with smooth, rather than treaded,
an asphalt supply truck at the project.
pneumatic tires. Scarifier or plow attachments
(2) Spreading equipment. Some cold mixes
may be mounted before, behind, or both before and
may be spread to the required depth without
behind the blade.
aeration. Generally, these are open-graded mixes,
(d) Asphalt distributor. The asphalt distrib-
placed under climatic conditions that will allow
utor is a key piece of equipment in cold mix
construction, particularly when rotary pulverizer
sonable time. They may be spread by a travel
mixers without built-in asphalt feed are used, or
plant, from windrows by motor grader or by large
when blade mixing is utilized. The asphalt distrib-
multipurpose equipment, such as a cutter-trimmer-
spreader. On the latter machine, guidance and
utor, either truck, or trailer-mounted, consists of
grade are electronically controlled by sensors that
an insulated tank, self-contained heating system, a
take reference from wires stretched along one or
pump, and a spray bar and nozzles through which
both sides of the roadway.
the liquid asphalt is applied under pressure onto
b. Mixed-in-Place Construction.
the prepared aggregate materials (fig 4-51). As-
(1) Windrows. Several types of cold-mix con-
phalt distributors range in performance and capa-
struction require that the aggregates be placed in
bility, with some capable of spreading up to 15 feet