The Bossier banner. [volume] (Bellevue, Bossier Parish, La.) 1859-1952, 1916-06-22
POPULARITY OF
CONCRETE ROADS
Rapid Increase Of Mileage In
Recent Years.
BOTH DURABLE AND SMOOTH

trasted In a New Bulletin Of the Do.
partment Of Asrieulture-Adviee For
Construction Of Concrete Highways.
The mileage of concrete pavement In
the United States has increased rapid
ly, and it is 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 it was only 364 900 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 mainte-
nance until renewals are necessary.
Availability Us base for another
type of surface If 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-
tions to certain degree by covering
the concrete pavement with bitumi-
nous wearing surface At the present
time the specialists in the department
justified, although it is possible that
future investigation may change the
situation in this respect. In the pres
ent state Of road science, however, 1t
seems that where traffic conditions are
| such that bituminous surface on con-
crete road is practicable bituminous
surface macadam road would be equal
ly practicable and certainly cheaper.
Where traffic is too heavy for macadam
road the bituminous surface is likely
to give way and the uneven manner in
which it fails tends to produce Excess
sive wear ON portions of the concrete
For successful concrete road, hard
ness, toughness and uniformity are the
most essential qualities. These can be
secured to great extent by care in the
selection Of the constituent materials
and the proportions in which they are
mixed. The cement, it is said, should
always conform to some standard spec
ifications 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 OF
gravel. In either case it is very desira.
BILE that the coarse aggregate be well
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
the proportion Of sand to coarse aggre
gate not less than one and one-half tt
, three, nor greater than two to three
. A'useful formula when gravel Is used
as coarse aggregate Is one part Of &c
ment to one and one-half parts of sani
| fC arfc nf II
ed stone is used one and three-quar
. ter parts Of sand may be substituted
, in place Of one and one-half parts.
, In addition to discussing the engi
, neering details of construction the bul
, letin calls attention to the fact tha
ordinarily from one-third to one-half O
, the total cost of constructing a con
crete pavement is for labor after tn,
, materials are delivered.
The most economical method Is {,
, have the work Of mixing and placin;
) the concrete as nearly continuous a
. practicable. The work should be plan
. ned with a primary view Of keep1n,
the mixer going full time. The drain
E age structures, the grading and tn
a sub grade should, therefore, be com
q pleted we'll in advance Of the mike
and provision made for obtaining al
y Of the necessary materials without dc
lay. A common error is the failure t
e make adequate provision for deliver
: ing water on the work and the amour
:. which given stream is capable of SUI
lying Is frequently Overestimated.
Congress and Good Roads.
Congress will have the good road