The Jasper news. [volume] (Jasper, Missouri) 1898-1924, 1917-09-13
Constitute About 0ne-Thlrd Of
Surfaced Roads In the
United States.
BEST SELECTION OF GRAVEL
Quality Of Material ls Next In impor-
tance to Proper Drainage-clay 10
Poorest cementine Material
We Have.

Roads that are artifcially surfaced
with gravel, or with earthly material
in the composition of which gravel pre-
dominates, are called gravel roads.
This designation covers a variation In
type which ranges from roads sur
faced with a natural sand-clay mixture
containing considerable percentage
of gravel 20 those having so-called
"gravel macadam" surfaces, composed
almost wholly Of pebbles and con-
structed in practically the same man
ner as first-class macadAm roads. Grav.
ell roads constitute about one-third the
total mileage of surfaced roads in the
United States and are confined to no
especial section Of the country.
In the following discussion Of gravel
roads it is convenient to consider the
subject under the two general heads,
Selection of Gravel" and "Construc-
tion Methods"
Selection Of Gravel.
Ordinarily the selection of gravel for
use in road surfaclng must be confined
to local materials which are or can
be made suitable for that purpose.
Because of high freight costs 1t seldom
happens that road gravel Of even the
very best quality Is transported by rail
greater distance than about 100
miles from the source of supply, and
in the vast majority Of cases 1t Is
hauled directly from pit to road in
wagons. Since the quality Of gravel
varies to considerable extent, some
times in different parts of the same
pit, it Is essential that local road off,
cials, who frequently are charged with
the selection Of such material, should
have some knowledge of the relation
between the physical characteristics Of
gravel and it's wearing qualities when
placed in road surface. While such
knowledge can best be gained by ac-
tual experience with different kinds of
gravel, there are certain general re-
qulrements which may be stated for
the guidance of the inexperienced.
For example, the following excerpt
from Bulletin No. 2 of the Michigan
state highway department presents In
very concise form the characteristics
which gravel for road surfacing should
possess, in the judgment Of the state
highway commissioner, in order to
meet the Michigan conditions.
Gravels that come from the pit with
the pebbles cemented together, even
though they contain no clay, will re-
cement in the road and become harder
than they were In the pit. Tests of
specimens Of this kind always show
usually some iron, both of which are
excellent cementing materials. Brief
ly, the experience of the state high
way department warrants the state
merit that there are few, If any, bank
grayels in Michigan that do not con
pebbles which grind up under traffic
TO furnish sufficient binder to carsS
them to consolidate in few months
time If separated from the surplus
sand and earth, and properly treatet
after applying to the road.
In accordance with these sugges
tions, gravels are considered valuabl,
for road purposes In the following
order:
|. Almost in direct proportion to tn
percentage of pebbles constituting tn
mass.
.. In direct proportion to the valu
as road metal Of the rock fragment
constituting the pebbles.
~no>-..1n.e--.oo---> S..n-z->->1ean.