For resurfacing over existing pavement, asphaltic-concrete pavement
is hereby prescribed, approved and adopted, the same to be in accordance
with the requirements set forth in this article.
[Amended 7-3-1990 by L.L. No. 5-1990]
A. Preparation of old surface. Cleaning of the old pavement, adjusting
of manhole heads, patching holes and application of the tack coat
as required and as hereinafter specified shall be done sufficiently
in advance of placing the new wearing course so that this operation
can proceed without interruption. Special attention shall be given
to providing a well-compacted foundation for the new wearing course
around the manhole heads after adjusting.
B. Resurfacing procedure.
(1) On the old surface prepared as above shall be placed an asphaltic-concrete
wearing course, two inches, more or less, in thickness after compaction,
on the existing pavement where and as directed by the Commissioner
of the Department of Public Works. Holes in old bituminous pavement
shall be thoroughly cleaned and filled with asphaltic concrete compacted
as directed before the new two-inch wearing course is laid. Depressions
over old sewer trenches or elsewhere, if ordered, shall be filled
up to the grade of the adjacent pavement with a wedge course of asphaltic
concrete thoroughly rolled before the new two-inch wearing course
is laid. The old pavement shall be thoroughly cleaned and, if ordered
by the Commissioner of the Department of Public Works, treated with
a tack coat of liquid asphaltic product applied with a pressure distributor
at a rate of about 10/100 of a gallon per square yard or as needed
to ensure a thorough bond between the old road surface and the new
construction. Over the tack coat the contractor shall spread asphaltic-concrete
wearing course material, to be leveled, raked and rolled with a ten-ton
roller to the satisfaction of the Commissioner of the Department of
Public Works and feathered out at the edges of the new work.
(2) At the discretion of the Commissioner of the Department of Public
Works, the tack coat may be omitted where there is sufficient life
in the old bituminous surface and resurfacing is two inches thick;
however, at all edges where the resurfacing course is to be feathered
out, the old pavement beneath shall be painted with the tack coat
material. Stone, brick and concrete gutters under the resurfacing
shall be similarly painted.
(3) If ordered by the Commissioner of the Department of Public Works,
any holes found in the existing concrete foundation under permanent
pavements shall be filled in by the contractor with 1:3:5 concrete.
At the discretion of the Commissioner, asphaltic-concrete binder material
may be used for this work instead of concrete.
(4) On curbed streets, the wearing course shall in general be raked out
along curbs so as to have a compressed thickness of about one inch.
Where the top of the curb is three inches or less above the existing
pavement in the gutter, the new wearing course shall be feathered
out and shall stop six inches from the curb or as directed by the
Commissioner.
C. Materials.
(1) In the wearing course, the graded stone aggregate mix shall consist of a graded stone aggregate passing a one-half-inch screen and all retained on a No. 10 screen, a graded fine aggregate of sand or stone screenings, all of which shall pass a No. 10 screen, a mineral filler and asphalt cement, all of which are to be proportioned and mixed according to approved manufacturer's specifications. It is intended that the paving mixture shall have an approximate composition as follows: 50% coarse aggregate, 36.5% fine aggregate, 6% mineral filler and 7.5% asphalt cement. The above percentages are not rigidly fixed and are subject to the final approval of the City's testing agency. See Subsection
G below.
(2) The binder course shall consist of a mixture of graded stone aggregate, all passing a one-inch screen and all retained on a No. 10 screen, a graded fine aggregate of sand or stone screenings, all of which shall pass a No. 10 screen, and asphalt cement, all to be proportioned and mixed according to approved manufacturer's specifications. It is intended that the paving mixture shall have an approximate composition as follows: 75% coarse aggregate, 20% fine aggregate and 5% asphalt cement. The above percentages are not rigidly fixed and are subject to the final approval of the City's testing agency. See Subsection
G below.
(3) Broken stone shall be produced from tough, durable rock and shall
be free from elongated pieces, soft or disintegrated stone, dirt or
other objectionable material.
(4) Sand shall consist of clean, hard, durable grains, free from clay,
loam and other foreign materials.
(5) Mineral filler shall consist of limestone dust or other approved
material.
(6) Asphalt cement shall be refined asphalt and flux, of suitable consistency
for paving purposes.
D. Tack coat. The tack coat shall be a quick-setting emulsified asphalt
or other type of liquid asphaltic product which, when applied to the
existing pavement, will ensure a thorough bond between the new construction
and the old road surface.
E. Spreading and rolling.
(1) Unless otherwise permitted by the Commissioner of the Department
of Public Works, the asphaltic concrete shall be placed by means of
a mechanical spreader so operated that the mixture as spread is free
from lumps, of uniform density and to the desired cross section.
(2) After spreading, the mixture shall be thoroughly and uniformly compressed
by a three-wheel, power-driven roller, weighing not less than 10 tons,
as soon after being spread as it will bear the roller without undue
displacement. Delays in rolling freshly spread mixture will not be
tolerated. Rolling shall start longitudinally at the sides and proceed
toward the center of the pavement, overlapping on successive trips
by at least 1/2 the width of a rear wheel. Alternative trips of the
roller shall be of slightly different lengths. The pavement shall
then be subjected to diagonal rolling in two directions with a tandem
roller weighing not less than 10 tons, the second diagonal rolling
crossing the lines of the first.
(3) The speed of the roller shall not exceed three miles per hour and
shall at all times be slow enough to avoid displacement of the mixture.
Any displacements occurring as a result of reversing the direction
of the roller or from any other cause shall at once be corrected by
the use of rakes and of fresh mixture where required. Rolling shall
proceed continuously until all roller markers are eliminated and until
the finished course shall have a density not less than 95% of the
laboratory-compacted density. If the surface course is being placed
at a rate in excess of 300 square yards per hour, the contractor shall
use an extra roller. To prevent adhesion of the mixture to the roller,
the wheels shall be kept properly moistened, but an excess of either
water or oil will not be permitted.
F. Smoothing irons. Heated smoothing irons shall be used to finish the
pavement along curbs, around manhole heads and elsewhere where necessary.
G. Intent of specifications; approval of sources of supply for aggregates
and mineral filler.
(1) It is the intent of these specifications to secure a pavement that
will conform to the latest construction specifications of the Asphalt
Institute. The contractor shall submit samples with manufacturer's
specifications for the asphaltic-concrete mixtures he proposes to
use in the work, and these are to be examined and passed upon by the
testing agency engaged by the City. The contractor shall make such
changes in the formulas submitted as may be required by the testing
agency in order that the mixture delivered and used in the work will
be such as to produce the pavement required.
(2) Approval of sources of supply for aggregates and mineral filler shall
be obtained from the Commissioner of the Department of Public Works
before being used in the mixture.
The work and materials for resurfacing on old concrete pavement
shall be the same as on old bituminous pavement, except:
A. All of the old pavement shall be sprayed with tack coat material
before asphaltic concrete is applied.
B. The compacted thickness of resurfacing shall be 2 1/2 inches,
unless otherwise called for in the job specifications.
The work and materials for resurfacing on old brick or stone-block
pavement shall be the same as on old bituminous pavement, except:
A. Resurfacing shall be two-course, 1 1/2 inches of binder course and 1 1/2 inches of wearing course (compacted thickness), unless otherwise called for in the job specifications. If sheet-mix is specified for the wearing course, it shall consist of a graded sand aggregate, all of which shall pass a No. 10 sieve, a mineral filler and asphalt cement, all of which are to be proportioned and mixed according to approved manufacturer's specifications. It is intended that the paving mixture called for under this item shall have an approximate composition as follows: 73% sand, 16% mineral filler and 11% asphalt cement. The above percentages are not rigidly fixed and are subject to the final approval of the City's testing agency. See §
104-13G.
B. Generally where binder course is used, the tack coat application
on the old pavement may be omitted.