Northern Wisconsin advertiser. [volume] (Wabeno, Wis.) 1898-1925, 1901-04-04

is an article by DIR. Il. X. Buckley,
assistant superintendent of the Wis
consin geological survey, on tar
macadam, theme that has been dis
cused in these columns heretofore
This kind of a pavement, says d.
Buckley, is really cross between an
asphalt pavement and macadam IN
the construction of asphalt pave
ment the principal constituent of the
wearing Surface Is sharp, angular
sand and asphalt In the wearing
surface of the tar macadam the
principal material is quartzite OF
hard granite rock. The tar is USED
simply as a bonding constituent ana
Is in nc way intended as part OF the
wearing surface of the pavement
The wearing capacity OF the TAR
macadam is measured entirely by the
hardness and strength Of the rock out
of which it is composed; only sur
ficient tar being used to unite the
fragments into a solid uniform mass.
Up to the present time these pave
ments have teen built more extensive
ly in Canada than in this country.
Toronto Ottawa, ana London, in the
province of Ontario, have been build
ing pavements of this character for
several years. In Fredonia and A1-
rora, New York, tar macadam pave
ments have also been constructed.
The following specifications for tar
macadam roadways as constructed in
London, Onto~io were furnished by
Ormsby Graydon, city engineer OF
London:
THE earth should be excayated and
blocks removed to a dept of twelve
inches below the line of finished
grade. This foundation should be
thoroughly wetted and rolled with
heavy horse rollers. Upon this
foundation should be placed six inches
of clean, coarse gravel, the gravel to
conform with the cross section and
finished grade of the street, and
should be wetted and rolled with q
steam roller. Upon the foundation OF
granite when thoroughly rolled should
then be placed three inches of coarse
grained, hard crushed stone capable
of passing through / " inch ring, 2,
per pent of which being fine crushed
and capable Of passing through \!
inch ring. Inc crushed stone should
be heated on steel platform in pans
to 100 degrees and on this heated
crushed stone. tar composition should
be poured until thoroughly covered
the tar TO be heated to the boilin;
point, 2l2 degrees and the pitch u
about 240 degrees, the whole to b'
thoroughly mixed in the same name
as concrete is mixed. After thorough
ly mixing 1t should be hauled on tn
street and graded evenly TO the rC
duired depth: then rolled with stear
roller When Thoroughly rolled,
second course two inches in depth 1
crushed stone capable of passin
through a / Y and l inch ring. r,
spectively, must be mixed in the sam
manner as regards heat, mixture. al
plication, etc, but need only be role
with the hand roller. Upon thi
second course must then be sprea
the finishing coat one inch in thicl
ness, composed of a thorough miStur
of sand. pitch, and tar; sand to
heated to at least 100 degrees. Thi
coat must then be applied while no
and spread evenly to the prope
thickness, and rolled with the ham
roller, After which the whole pave
ment should be thoroughly rolled wit
a steam roller, and sanded with DIR
sand one-half inch in depth. Tar
to be heated 212 degrees and pitcl
240 degrees and properly mixed at
rate of ten gallons of tar to one ga
Ion of pitch per cubic yard of crushe
stone; eleven gallons OF tar to one o
pitch per cubic yard of top coat
Stone must be good and hard n
limestone will be allowed. Coal ga
should be clean, containing no waite
gas tar Pitch should also be tn
best of its kind. manufactured fror
pure coal gas tar"
f.. b. Wingate. city engineer {
Hamilton. also furnishes specific;
tons for tar maeadam roadways d
constructed in that city. The follow
ing is copy:
"All earth or other material abol
the sub-grade must be excavated S
as to conform to the leve of the SUI
grade. which will be ten inches belo
the finished surfare of the roadway
and should the sub-grade be above tn
level OF the natural ground, the
earth must be deposited until tn
level of the sub-grade is reache,
The sub-grade must be shaped to tn
profile and cross section which will b
furnished by the city engineer. Afte
the sub-grade has been formed to tn
proper Gambler of the road. general
Y inch per foot or six inches for .
foot roadway, to be thoroughly role
with the steam roller. and II by thi
means soft spots are revealed, the
must be flied with good solid material
The first six inches OF stone must b
made in the ordinary way for
macadam or telford roadway thor
oughly rolled. II so required. II ma
be made OF hard broken stone. fur
mace clinkers, or brick rolled smootl
and finished TO the required Gambler O
the road. Upon this must be place,