This work shall consist of two courses of bituminous
concrete placed upon a completed base course. This work shall be performed
in accordance with these specifications and in conformity with the
typical sections for the class of street being constructed.
A.
The materials for this work shall conform to the requirements
of State Form 810, Article M.04.01, and shall be Class 1. At the time
of construction, the mixing plant supplying the material must meet
the requirements of the Connecticut State Highway Department for supplying
bituminous concrete for state and Town aid projects.
B.
At locations, such as drives, where special handling
of bituminous concrete materials may be necessary, bituminous concrete
Class 2 may be substituted for Class 1 with written permission of
the Town Engineer.
The methods employed in performing the work
and all equipment, tools, machinery and plant used in handling material
and executing any part of the work shall be subject to the approval
of the Town Engineer before the work is started and, whenever found
unsatisfactory, shall be changed and improved as required by the Town
Engineer. All equipment, tools, machinery and plant used must be maintained
in a satisfactory working condition.
A.
Paving equipment. Paving equipment shall be of the
self-powered type with an adapter to provide guidance of the screeding
action. The screed or strike-off member shall be adjustable to the
shape of the cross section of the finished pavement. Some method shall
be provided for the tilting of the screed while in operation to secure
the proper drag and to provide the compressive action necessary to
prevent pulling and to result in the uniformly screeded surface required.
The machine shall have a sufficient number of driving wheels so that
there will be no undue amount of slippage. Whenever the design of
the equipment and plan of operation are such that the driving wheels
travel on the finished surface of a completed pavement, said wheels
shall be equipped with rubber tires or other means to protect the
finished surface. Means shall be provided for heating the screeding
members by some method that will prevent accumulations of bituminous
material.
B.
Transportation of mixture. The mixture shall be transported
from the mixing plant in trucks having tight bodies which have been
previously cleaned of all foreign material. The use of kerosene, gasoline,
fuel oil or similar products for the coating of the inside of truck
bodies is strictly prohibited. Loaded trucks shall be tightly covered
with waterproof canvas or other suitable covers. The mixture shall
be delivered at a temperature of 250° to 310° F. The maximum
loss of temperature between plant and project shall not exceed 15°
F.
C.
Forms.
(1)
Forms will be required only if the equipment
and construction methods used fail to provide continuous and positive
mechanical control of the screed or strike-off assembly so as to strike
off the mixture to the exact grade and elevation intended or to place
the material along true lines designated without the aid of manual
adjustment during operation.
(2)
When required, forms shall be of a type and
construction approved by the Engineer.
D.
Placing of mixture.
(1)
Immediately before placing the mixture, the
area to be surfaced shall be thoroughly cleaned. When the first course
is used as a temporary wearing surface, it shall be thoroughly cleaned
and a tack coat applied just prior to placing the second course.
(2)
The mixture shall be laid only when the surface
is free of frost and dry and when the weather is not foggy or rainy.
Paving operations shall be carried on only when the temperature in
the shade is not less than 40° F. When overtaken by sudden storms,
only the amount of material actually in transit may be placed, provided
the mixture is within the temperature limits specified.
(3)
Upon arrival, the mixture shall be dumped into
the mechanical spreader and immediately spread and struck off to the
full width required and to such appropriate loose depth for each course
that, when the work is completed, the specified depth will be obtained.
(4)
The sequence of the bituminous concrete placing
operations shall be performed so as to obtain tight and well-compacted
longitudinal joints.
(5)
Before any rolling is started, the finished
surface shall be checked, any inequalities adjusted and all drippings,
i.e., fat, sandy accumulations from the screed and all fat spots from
any source, shall be removed and replaced by satisfactory material.
(6)
Contact surfaces of curbings, gutters, manholes,
etc., shall be painted with a thin, uniform coat of hot asphalt cement
or asphalt cement dissolved in naphtha just before the material is
placed against them.
(7)
The refueling of equipment in such position
that fuel might be spilled on bituminous concrete mixture already
placed or to be placed is prohibited.
(8)
Before mechanical equipment or hand tools are
cleaned, they shall be moved off the area paved or to be paved and
they shall not be returned for use until after they have been allowed
to dry.
E.
Compaction.
(1)
After spreading and when sufficient set has
developed to permit proper compaction, each course shall be compacted
by rolling consisting of initial or breakdown rolling, intermediate
rolling and final or finish rolling. Initial rolling shall be performed
with power-driven steel wheel, tandem or three-wheel rollers weighing
not less than 10 tons. Intermediate rolling shall be done with a self-propelled
pneumatic tire roller equipped with wide-tread compaction tires capable
of exerting an average contact pressure from 60 to 90 pounds per square
inch uniformly over the surface. Final rolling shall be done by a
power-driven steel wheel tandem roller weighing not less than 10 tons.
(2)
Rolling shall begin at the sides and progress
toward the center, parallel to the center line of the roadway, uniformly
lapping at least 1/2 the width of the compacting wheel of the roller.
Alternate trips of the roller shall be terminated in stops at least
three feet distant from any preceding stop. Rolling shall be discontinued
if the surface shows signs of excessive cracking or displacement and
shall be continued later. If it is found that the cracking and displacement
continues, the paving operation shall be discontinued until the condition
is corrected.
(3)
Rolling shall proceed continuously and in such
a manner that all roller marks are eliminated and all parts of the
pavement shall receive substantially equal compaction.
(4)
The density of the completed pavement shall
be not less than 95% and not more than 100% of the density obtained
from approved compacted Marshall molds.
(5)
For small places inaccessible to a roller, such
as adjacent to curbs, gutters, manholes, etc., the required compaction
shall be secured with tamps.
(6)
All depressions shall be remedied by adding
new material to form a true and even surface. All high spots, high
joints and other defects shall be adjusted as directed by the Engineer.
F.
Joints. Placing of the courses shall be as nearly
continuous as possible and the roller shall pass over the unprotected
end of the freshly laid mixture only when the laying of the course
is discontinued or interrupted for an appreciable period, and joints
shall be formed at such points. Where joints are to be formed, the
end of the freshly laid mixture shall be cut square with the pavement
slightly set up with the back of a metal lute and rolled at slow roller
speed so as to cause as little feathering as possible. Before new
material is laid, the joint shall be cut back and a thin coating of
hot asphalt applied to the joint. Care shall be taken to keep the
asphalt paint off the surface of the pavement.
G.
Test of finished pavement.
(1)
The finished pavement shall be such that it
will not vary more than 1/4 inch from a ten-foot straight edge applied
parallel to the center line of the pavement. Any irregularity of the
surface exceeding the above limits shall be corrected.
(2)
When the total combined thickness of the two
courses is less than that required by more than 5/8 inch, the situation
shall be corrected by a method approved by the Engineer.
H.
Protection of the work. Sections of the newly finished
work shall be protected from traffic until they have become properly
hardened by cooling.
