Concrete curbing shall consist of Class C concrete
constructed on the prepared subbase in accordance with the dimensions
and details shown on the plans or as ordered and in conformity with
these specifications.
The concrete and joint filler shall conform
to the requirements of State Form 810, Article M.03.01.
Construction methods for concrete curbing shall
conform to the requirements of State Form 810, Article 6.01.03, as
supplemented by the following requirements:
A. Excavation. Excavation shall be made to the required
depth, and the base upon which the curbing is to be set shall be compacted
to a firm, even surface.
B. Forms. Forms shall be so constructed that the form
for exposed faces may be removed before the concrete has taken final
set in order to permit correction of surface irregularities.
C. Placing of concrete.
(1)
The concrete shall contain not less than 5%
nor more than 7% entrained air at the time the concrete is deposited
within the forms. Concrete shall be placed only on a moist base. Concrete
shall not be placed on a soft, muddy or frozen base.
(2)
The concrete shall be placed in the forms, struck
off with a template, compacted by approved means and finished to a
smooth, even surface. Vibration will not be required.
(3)
The plain cement concrete curbing shall be constructed
in sections having a uniform length of approximately 10 feet, unless
otherwise directed. The length of these sections may be varied slightly
where necessary for closures, but no section less than six feet in
length will be permitted. These sections shall be separated by an
approved method at the time of placing of the concrete.
D. Curing.
(1)
Curing shall be done with a liquid membrane-forming
curing compound approved by the Engineer. The material shall be a
combination curer-hardener-sealer-type compound and shall be similar
or equal to Demicon Temp Color as manufactured by the McMillan Products
Division of the Hausman Steel Company of Detroit, Michigan. The rate
of application shall be in accordance with the manufacturer's instructions.
(2)
The curing compound shall be applied to all
exposed surfaces of the concrete immediately following the disappearance
of the water sheen following the final finishing and before any marked
dehydration of the concrete or surface checking occurs.
(3)
When the forms are removed before seven days
after the concrete has been placed, the exposed sides shall be covered
with the compound at the same rate as applied to the surface.
(4)
If the film is damaged by rain or in any other
way before drying, the curing compound shall be reapplied to the affected
areas.
E. Backfilling. After the concrete has set sufficiently,
the grading shall be completed to the lines shown on the plans or
as ordered by refilling to the required elevation with approved material
which shall be placed in layers of not over six inches in depth and
compacted until firm and solid.