The Washburn leader. [volume] (Washburn, McLean County, N.D.) 1890-1986, 1915-11-05
POPULARITY OF
CONCRETE ROADS,
Rapid Increase Of Mileage 10
Recent Years.
BOTH DURABLE AND SMOOTH

BOTH DURABLE AND SMOOTH
Advantages and Disadvantages Con-
trastsd In q New Bulletin Of the De-
partmsnt Of AsrieuIturs-Advies For
Construction Of Concrete hishways.
The mileage Of concrete pavement In
the United States has increased rapid
", and 1t IL likely to continue to In"
crease, according to a new bulletin Of
the department Of agriculture. This
bulletin gives the estimated amount OF
| concrete pavement in the United States
in 1914 as 100000 square yards. In
1909 1t was only 1854 1000 square yards.
The principal advantages of concrete
pavements which have led to this In
crease In popularity are said to be:
Durability under ordinary traffic con-
| ditiOns.
A smooth, even surface. offering little
resistance.
Absence of dust and ease with which
it may be cleaned.
Comparatively small cost Of mninte-
nance until renewals are necessary.
Availability as n base for another
type Of surface ii desirable.
Attractive appearance.
The disadvantages of concrete as .
road surface are:
Its noise under horse traffic.
The wearing Of the necessary joints
in the pavement and the tendency to
crack. with its consequent rapid de-
terioratiOn.
The difficulty Of repairs when these
become necessary.
In the past efforts have frequently
been made to overcome these objec-
tons to a certain degree by covering
the concrete pavement with a bitumi-
nous wearing surface. At the present
time the specialists In the department
hold that this cannot he economically
justified. although 1t Is possible that
future investigation may change the
situation In this respect. In the pres
ent state Of road science. however, It
seems that where traffic conditions are
such that bituminous surface on q con
crete road is practicable q bituminous
surface macadam road would be equal.
ly practicable and certainly cheaper
Where traffic Is too heavy for macadam
to give way and the never manner in
which It fails tends to produce cxces-
sive e on portions Of the concrete.
For a successful concrete road. hard
ness, toughness and uniformity are the
most essential qualities. These can be
secured to a great extent by care In the
selection Of the constituent materials
and the proportions in which they are
mixed. The cement. 1t Is said. should
always conform to some standard spec
ifcations for portland cement. such
as those issued by the United States
bureau Of standards or the American
Society For Testing Materials. The
sand should not contain more than 3
per cent of foreign material. and sand
with more coarse than fine grains is to
be preferred. The coarse aggregate
may consist Of either crushed stone or
gravel. In either case it is very desira-
| nIC lltL luN NVulSG ASSl Ss UC we'll
graded In size between proper limits.
The proportion Of cement to the sand
and coarse aggregate combined should
not be less than about one to FIVE, and
tie proportion OF sand to coarse aggre-
gate not less than one and one-half to
three. nor greater than two to three.
4 useful formula when gravel Is used
as coarse aggregate is n part Of &C.
ment to n and one-half parts Of sand
to three parts Of gravel. When crush
ed stone is used n and three-quar-
ter parts Of sand may be substituted
In place Of n and one-half parts.
In addition to discussing the engl-
neering details Of construction the bull
letin calls attention to the fact that
ordinarily from one-third to one-half Of
the total cost of constructing q con-
crete pavement is for labor after the
materials are delivered.
The most economical method Is to
have the work Of mixing and placing
the concrete as nearly continuous as
practicable. The work should be PLAN
ned with a primary view Of keer'n:
the mixer going full time. The drain
age structures. the grading and no
sub grade should, therefore, be COM
plcted well in advance Of the m;:.rr
and provision made for obtainir.' al
Of the necessary materials withU,.' .l.-
lay. A common error is the fai.rt" Il,
make adequate provision for del: ,r-
ing water on the work and the an,""mt
which a given stream is capable OF sup
lying Is frequently overestimated.
Congress and Good Roads,