the tank trucks are being switched. As soon as the
point water is added through spray nozzles and the
first windrow is mixed and spread on one section
remaining paddles complete the mixing. A strike-
of the roadway, it is compacted. At the same time
off attached to the mixing machine spreads the
a second windrow is being mixed and spread. It in
mixed soil-cement. If a motor grader is used to
turn is then compacted. Finishing of the entire
spread the mixture and a tamping roller is used
roadway is completed in one operation. Water
for compaction, the mixture should first be loos-
requirements are based on the quantity of soil
ened to ready it for compaction. If two windrows
material and cement per unit length of windrow.
have been made, the mixing machine progresses
See figures 4-10 and 4-11 for construction se-
350 to 500 feet along one windrow and then is
quences for windrow-type operations.
backed up to process the other windrow for 700 to
2. Multishaft traveling mixing machine.
1,000 feet. The cement spreading operation is kept
Since most multi-shaft traveling mixing machines
just ahead of the mixing operation. Water is
have a high-speed pulverizing rotor, preliminary
supplied by tank trucks. A water tank installed on
pulverization is usually unnecessary. The only
preparation required is shaping the soil material
the mixer will permit continuous operation while
Figure 4-10. Sketch of soil-cement processing operations with windrow-type traveling pugmill.