The area of the roadbed upon which the pavement
structure, including subbase, is placed shall be known as the "subgrade."
This is the plane coincident with the bottom of the subbase as shown
on the typical sections.
A.
All soft and yielding material and other portions
of the subgrade which will not compact readily when rolled, vibrated
or tamped shall be removed and replaced with suitable material. The
surface shall be compacted uniformly by rolling with an approved power
roller having a minimum compression of 300 pounds per inch of width
of tread on the rear wheel or wheels and weighing not less than 10
tons, or with an equivalent vibratory roller or compactor.
B.
When more than one compacting unit is used, the unit
exerting the greatest compactive effort shall be used to make the
initial compaction. Any portion of the subgrade which is not accessible
to a roller or other compacting unit shall be compacted thoroughly
with hand tampers or with approved mechanical vibrators.
C.
The rolling, vibrating or tamping shall be continued
until the entire subgrade is uniformly and thoroughly compacted true
to lines and grade given.
D.
The contractor shall protect the subgrade from damage
by exercising such precautions as are necessary. At all times the
subgrade surface shall be kept in such condition that it will drain
readily and correctly. The subgrade shall be checked and approved
by the Town Engineer before any foundation or surfacing material is
placed thereon.
