Polk County observer. (Monmouth, Polk County, Or.) 1888-1927, 1910-12-09

applying biturainous binder to thu
roads, the first being a surface meth
| cd, generally called tar spraying
which may be carried out either by
hand or by machinery, and which un-
der favorable circumstances binds the
surface to depth of about 20 nm
BY favorable conditions is meant thai
the tar is applied when the roadways
are thoroughly dry, and the existing
dust thoroughly cleansed from them
before the tar is applied. In wet
weather 1t is difficult to obtain these
conditions, and the penetration of the
tar below the surface and it's durabl-
ity are thereby much reduced, but, un-
der the most favorable circumstances
this surface application of tar can only
be expected to bind the surface for one
season, so that it Is evident that the
more complete method of impregnat-
ing the whole of the road material to
depth of 80 nm. from the surface
line must be eventually carried out.
Whenever this has to be done to exist
ing roads the material must be remov-
ed to the full depth of 80 MN. and re-
placed by layer Of tarred aggregate,
rolled down to the same thickness,
this aggregate consisting of impreg-
mated angular pieces of granite or ba-
salt, of such size that they will pass
through 60 nm. ring, combined with
sufficient smaller particles to fill up the
interstical spaces, so that the tar prev
iously applied to the large and the
small material fills up the remaining
spaces and renders the road nonpo-
rous, and hence prevents the surface
water, either the rain or that from
artificial watering, from penetrating it.
"a roadway so formed becomes SO
waterproof and so durable that it can
be laid with a cross-fall or Gambler
which need in no case exceed l in so.
and in many cases will yield satisfac-
tory results with the smaller cross-fall
of 1 in 60. 1t is important that this
top material should be rolled with
light rollers which must
never exceed 10000 kilos, in weight, |
for it has been found a great mistake
to use rollers exceeding this weight, as
they are liable to crush the new ma
terial, exposing new untarred surfaces,
and hence preventing satisfactory wa
terproofing. The cost of such water
proof coatings has been found in Eng |
land not to exceed 2.30f. per square
metre on the average and from eX-
perience already obtained it is be-
coating will last from six to ten years
without renewal; but to obtain the
best results it is advisable to make
certain that the surface remains wa
terproof by giving it a light water
proofng coating of tar by spraying
every year or every alternate year.
"Roads SO prepared and so treated
possess in a maximum degree the quail
ties of being noiseless, of cleanliness,
ease of scavenging, requiring little or
10 artificial watering during dry sea-
IONS. The author considers that the use
If this class of road will become uni
,ersal for all the light traflcked streets
If our large towns and for all the
Itreets of our small towns, and that it
will in many cases be found to advan-
ageously take the place of the more
pavements which have been
lsed in the second class of more high
y trafflcked streets.
THE author proposes to leave to
,thers the discussion of the best meth
IDS of constructing the wood or as
,halt-paved streets of the second I
lass and of the granite paved streets
If the third class. Great perfection
las been arrived at in London in the
wood and asphalt pavement streets,
md we find the streets forming the
locks and quays of Liverpool and
glasgow form excellent examples of
pavement of the third class.
Summarizing, the author believes
hat the improved waterproofed mac
dam herein indicated Is satisfact-
ry solution of the problem of deal
ng with the roadways of the major
ty of our streets of all our towns and
hat the other problems of dealing
With the second and third class of
Dads are already satisfactorily met by
he wood pavements and the granite
avements which are already so large
Y in use."