Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1905-08-05

the Year Causes of Failure In
Building Them.
II IL n matter Of common observation
that here and there in the southern
states are to be found stretches OF
sand.clay roads never known to be
bad, says W. l.. Spoon in the yearbook
of the department OF agriculture This
fact has led to study OF the reasons
why such roads are always good. Nj
mcrous experiments have been made
with varying results, but all indicate
that the essentials to success In sand
clay road building are pudding and
SaturatiOn. What Is meant by pud-
ding or mixing may be clearly under
stood by any one familiar with the op-
erations In the process of briCkmnking
The clay must be rendered homogene-
Gus, and this can be done only by the
addition of water during the process
until the clay becomes plastic, like
dough. The second essential is the I'D
dillon OF sand to the point OF sntura-
ton but not beyond
No sand-Clay road can satisfactorily
withstand the severity of public travel
without having first been reduced to q
compact homogeneous mass OF sand
and clay Each grain Of sand should
be In touch with other grains on all
sides. Such condition cannot be Sc
cured without the agency Of water. 1t
is useless to roll n dry sand-clny road
before II has been rendered hOmoge-
neous by the pudding process and the
grains OF sand have been brought into
contact, with only the intersticcs be
tween them filled with clay as n bind
cr. The first operation is mixing; the
second IS rolling as the mixture dries
This forces the particles Of sand to
gether. and any excess OF clay tends
to rise to the surface, rendering II
sticky. This clay must In turn be
snnded and the operations repeated I'M
til the surface has become hard and
compact.
Many failures have been made in the
building Of sand-Clay roads, and few
of the more common causes for these
failures will be pointed out The first
cause of failure is the want OF perfect
drainage. The imperfections may be
In the cross sectional drainage, the
side bitches or the drainage of the
subgrade or rOadbed. 1t is customary
to give to n sand-Clay road n little
greater crown than is usually given
to macadam road, especially where
the grade is above 3 per cent The
subject of side bitches should have
more careful consideration than Is usu-
ally given in case of maCadam roads
II the subsoil upon which the road is
built is clay 1t is important that the
bottom of the side bitches should be
eighteen inches or more below the
crown or middle of the Travelled track
If, on the other hand, the land is roll
ing and the subsoIl Is sand of consld-
cradle depth, thus giving perfect nat
ural drainage to the roadbed, little or
no side ditch will be required.
Perhaps the most common error in
drainage is the failure to drain proper
ly and thoroughly all places where
there nre wet weather springs II
'
so rs TO locate 1t upon dry ground. as
even the deepest side bitches practica-
bic may fail to give relief where such
springs exist. 1t is important to avoid
deep cuts and to carefully consider all
probable sources of trouble The writ
er has often seen old roadbedS with
water ooZing from all parts during Il
rainy season in spite Of sufficient side
bitches, the water even rising in the
center of twenty foot roadbed and
standing on the surface or slowly run
ming along the wheel tracks to the
nearest mudhole 1t should be remem-
bered that water, beyond very lin
tied amount, adds nothing Of value to
the sand-clay road after 1t is com
pleted. If water is always present.
sand should be used without clay
Sand and water make better road
than sand and clay and water In
proof Of this statement attention need
only be called to the numerous places
where water crosses the roads in sandy
districts Such fords are always COM
paratively solid.
Another cause Of failure is the want
of thorough mixing There may be a
proper amount of sand, and clay may
be placed upon the road, yet II 1t Is
not thoroughly puddled and mixed to
saturation in every place the road IS
not likely to withstand public travel
Some sections will break and become
loose sand, while others Will become
muddy in wet weather and hard in
dry weather. Such variations may oc-
cur every few feet and even at the
same place one wheel track being In
loose and the other in mud
In northern sections frost is another
cause of failure and one more difficult
TO deal with than any heretofore men
toned. Frost is temporarily destruc-
tive to Il sand-clay road. and for that
reason the mixture must extend below
the frost line If the road is built ON a
clay foundation. Freezing disinte-
CRATES the sand-clay composition and
makes of 1t Il soft, slushy mud. which
however, repacks again after each
heavy rain, although frequently leav-
Therefore in general practice 1t is
necessary to make the sandclay mix
= re Of such depth as to extend a
Jew inches below the frost line.
Other causes of failure are the i'm
proper selection of clay and the i'm