Free trader-journal and Ottawa fair dealer. (Ottawa, Ill.) 1920-1927, 1920-03-25

the total bitumen soluble In carbon
tetrachloride.
t12) The fixed ca. BON shall not eS-
coed II ser cent.
The proportion Il the various in
gradients composing the asphaltic
concrete wearing surface shall be as
follows:
Bitumen. per cent to . per cent,
Mineral aggregate
Passing 200 mesh screen, 7 per cent
to 10 per cent.
Passing 80 mesh screen. but retain
ed on a 200, 10 per cent 20 20 per cent
Passing 40 mesh screen, but retain
ed on an 80. 10 per cent to 20 per cent
Passing 20 mesh screen. but retain
ed. on a 40, 10 per cent to % per cent.
Passing 8 mesh screen. but retained
on 20. 10 per cent to 20 per cent
Passing 4 mesh screen, but retained
on an s, Is per cent to 20 per cent
Passing 2 mesh screen, but retained
on a 4, j per cent to 10 per cent.
The minimum amount of btumen
allowed shall be used only In mixtures
containing the minimum total passing
the so mesh. The percentage OF BIZ
tumen must be increased above the
minimum as the total passing the So
mesh increases,
The item designated as dust in
Cl,Ides, h%addition to the stone dust or
Portland Sement that may be added.
such fine sand passing 2O0~mesh
screen as may he found selt'contained
In the sand to be used. and such 200
mesh material as may be self-Contain-
ed In the refined asphalt.
METHOD OF MIXING; The aggre-
gate shall be dried and heated In
properly designated driers before mix.
ing with the asphaltic cement The
driers shall be of the revolving type,
thoroughly agitating and turning the
materials during the process Of dry
ing When the aggregate is thoroughly
dried and heated to a temperature of
from 200 to $50 degrees f., depending
upon the asphaltic cement used, it
shall be Immediately before cooling or
exposure to moisture. mixed with the
hot aspha'tic cement ds hereinafter
specified If stone dust is used, it
shall be introduced directly into the
mixer without passing through the
drier.
The asphaltic cement shall be melt
ed In tank arranged so the heat can
be properly and easily controlled and
regulated. When melted and raised
to temperature of from poo to $50
degrees f., it shall be combined in
the proper proportions with The hot
aggregate and Immediately mixed in
properly designed revolving mixer
until a thorough and intimate mixture
OF the ingredients has been aceomp-
lished and the particles composing the
aggregate are evenly and thoroughly
coated with the asphaltic cement
The mixer shall not be exposed direct
ly to the action of the fire.
METHOD or LAYING: While still
hot from the mixer the paving mix
ture shall be spread evenly on tho
foundation with hot iron rakcS and
shovels, so that when cOmpressed
with the rL'ler, /. hall have the thick
ness specified with the surface even
and true to grade. Along the curb an
around the manholes. catch basins
and other distractions. In the street
where the roller cannot reach, the
compression shall be secured by the
use OF hot hampers. The rolling anC
tamping shall be done as quickly rs
possible after the material is spread
while still hot and pliable. When thc
paving mixture is hauled on the street
In dump wagons it shall be kept GOV
cred with canvas to retain heat. dump
ed on platforms and shoveled into
place and raked to the proper grade
As soon as spread the paving mixture
shall be rolled with a tandem roller
weighing at least six t6) tons and tbs
rolling continued. working lengthwisc
and diagonally of the street. when
practicable. additional compression in
the wearing surface should be secured
by the use of a ten I0) ton roller
Rolling must be steadily kept up and
continued until all roller marks shall
disappear and the surface gives indi
cations of no further comprcssibility
The paving shall 1e done contin
uOusly, as the number of joints be
tween hot and cold material may be
reduced to the minimum. When it is
not practicable to lay it continuously
and joint is unavoidable the edge
of the cold material shall be trimmed
down to rough feather edge. and the
surface, where the Joint is to be made
painted over with asphaltic cement
the hot material raked over the feath
cred edge and thoroughly rolled. In
stead of trimming the cold material
joint strips MAJ be used consisting
of strips of canvas about eighteen
1S) inches wide with three parallel
lines OF three-quarter "a inch ropes
seWed on the under side about three
inchs apart. The Joint strips shall b.
laid on the feather edge of the freshl,
raked material with the upper rope al
the line where the thickness begins
to decrease and the rolling complete
on top OF the canvas as for finished
pavement The faces of the curb an
gutter. iron castings. etc. shall bt
painted with asphaltic cement before
the paving mixture is laid.
SURFACE FINISH: As soon as
possible after the rolling of the mix
ture is finished. and while the surface
is still fresh and clean. and, if pos
sible. while warm, a seal coat Of as
pnaltic cement of proper consistency
TO be flexible when cold. shall be
spread over the surface. 1t shall be
applied while at a temperature o
from 200 degrees to $40 degrees f,
depending upon the asphaltic cemen
used, and evenly spread with rubber
squeeges or mops. Only sufficien
coat shall be spread to flush the sur
face voids without leaving an excess
Immediately over this a top dressin.
TN