The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1918-09-06
DEFINING ROADBEDS

the use OF the WOrQ concrete In Ln(
petitions recently circulated in thil
county for new road surfaces, and ii
order to clear it up, this paper ha,
consulted the Twentieth Century
Encyclopedia and Nelson's Interna
tional. revised to 1918, and gives
their definitions.
Concrete
Concrete Is a mixture of sand
rock and cement, and is usually In
the proportion of 1:2:4, or 1:4.9 II
poorer quality is permissible
Concrete is of three kinds, monoli
THO, cement blocks and reinforced
Monolithic is that which is made In
mass. being moulded in the place OF
psition 1t is to occupy, and includes
foundations, walls, sub-pavement and
the like. Cement blocks are moulded
in much the same manner as brick
and are laid in place after being
cured. Reinforced concrete IL
moulded in position like monolithic
but has rods of steel imbeded in II
to give tensile strength to match the
resistance of the mass.
Concrete is presumed to be a solid
mass, the materials being graded in
size so that the voids between the
larger pieces shall be filled by those
of smaller size down to the fineness
of -four. The gravel or rock used is
of three grades or sizes technically
known as fine aggregate, coarse az
gregate and man-size, meaning these
OF such size that one man can place
them in position. The fine aggregate
is such size as will pass thru q
Quarter-inch mesh or square. The
coarse aggregate includes sizes larger
than pea gravel and smaller than
man-size.
Bitulithic paving differs from con-
crete in having different material
for a binder. While cement and
water afford the binding force for
concrete, bitulithic roadbed is
bound together by asphalt, pitch, pc
troleum, naphtha, elaterite, cocker
lite, gilsonite or some element or
combination made from them, or
from mineral oils taken from shale
or marie.
The particular material used is
made boiling hot and is poured on
the bed Of crushed rock, after spread
ing and rolling hard, and is then
rolled and covered with finer rock
and sand and another coat Of binder
Is poured on hot and rolled again.
The binder fooks like hot tar and in
warm weather it is slightly springy
in the rocky mass: 1t excludes water
from the mass, and saves it from
heaving by heavy freezing. Concrete
is not so immune from heaving and
cracking due to absorbing water and
freezing.
(Dollarway paving resembles Bit
.ulithic and is of cheaper .construc-
tion.)
Macadam road is made of crushed
or angular pieces of rock without
using binder of any kind. The
rock must be small enough to p ass
thru two and half inch screen or
ring, and must be hard and tough
and of varying sizes so the voids will
fill. Rock that is hard and brittle
is not suitable because it pulverizes
and the dust washes or blows away.
The original rule of the two and
half inch size is not always adhered
to, and it is customary to have the
larger parts of the mass in the bot
tom or lower strata, and the finer
ones on the top to make it smooth.
In the further discussion of road
beds in this paper we shall speak of
four kinds of roads, classed as fol-
lows:
Earth roads, designating those
that are merely the local soil made
into some kind of grade.
Graveled roads, meaning those
that have layer or layers of. fine
gravel rolled hard to press the gravel
into the soil to tougher the surface.
Macadm, meaning earth roads
covered with layer or layers of
crushed rock or fine gravel to make
a wearing surface, but no attempt
made to press it into or mix it with
the soil. The coat of rock or gravel
is expected to pack hard and smooth. |
Bound roads, meaning concrete,
dOllarway or any combina-
ton of rock with binder. (Clip these
four definitions for reference
Locations for High Lines
In adopting the locations for high |
lines, we recommend making those |
frst that are at the seat of the great
est amount Of coal and gravel to be
handled at the beginning of the road
Taking the statements
Of most people, that the road from
Blackfoot west to the northern ap-
proach to Snake river bridge has the
most traffic of any section in the
county, that should be treated first.
A high line could be built at the
edge Of the bench by the canning
factory by constructing few hun
1red feet of switch and the necessary
.restle and bins. 1t would place the
'oad materials right by the side of
he place where it is to be used, and
would be within reach of several
'oads needing attention as soon as
hey can be reached, including the
ANDY section on the Riverside road
wing less than a mile west Of the
bridge. This high line would afford
distributing station for gravel for
Use between the rivers as far as it ia
desirable to haul it, and for coal for
I'll the country between the rivers.
vest OF Snake river as far as they
jared to haul, and for the town Of
3lackfoot.
Dealers Nav Object