Page 399 - Moving the Earth_ The Workbook of Excavation

ROADWAYS

ROADWAYS 8.61

Final grading is followed immediately by moistening, and compaction with a pneumatic-tired
roller. (See Fig. 8.47.)
If another layer of soil-cement is to be built on top of this one, exact surface grade is not crit-
ical, and compaction planes need not be roughened. (See Fig. 8.48.)

Joints. Joints occur at the end of each day’s construction, and between parallel work strips.
A vertical joint at the end of a day is made by cutting straight down into the mixed and compacted
material, either immediately after stopping work or before starting the next morning. The toe of a grader
blade, a special disk attachment on a blade, or hand grub axes or shovels may be used. (See Fig. 8.49.)
When work is started again, the cut surface is brushed clean of loose material, dampened, and
new mix placed against it. Compaction may be by a roller or grader operated across the road, or by
a hand vibrator or tamper. Excess material should be placed at the fresh side, to be pressed into the
joint by regular longitudinal rolling. Remaining excess, if any, can be bladed off when finishing.
A longitudinal joint between two work strips is made by overlapping the mixer a few inches, if
the material is still fresh and soft, or only partially hardened. Test holes may be made with a pick
to locate the firm edge of the original strip, and stakes or string placed as a guide for the operator.

FIGURE 8.47 Another processing sequence. (Courtesy of Portland Cement Association.)

FIGURE 8.48 Multiple-shaft mixer and compactor. (Courtesy of Portland Cement Association.)