Essex County herald. [volume] (Guildhall, Vt.) 1873-1964, 1915-11-19
POPULARITY OF
CONCRETE ROADS
Rapid Increase Of Mileage In
Recent Years.
BOTH DURABLE AND SMOOTH

Advantages and Disadvantages Con-
trasted In a New Bulletin of the De-
partment of AgrcuIture-Advice 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 364O0O 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 as a base for another
type of surface if desirable.
Attractive appearance.
The disadvantages Of concrete as
road surface are:
It's noise under horse traffic.
The wearing of the necessary joints
in the pavement and the tendency to
crack, with it's consequent rapid de-
terioration.
The difficulty of repairs when these
become necessary.
In the past efforts have frequently
been made to overcome these objec-
lions to a certain degree by covering
the concrete pavement with bitumi-
nous wearing surface. At the present
time the specialists in the department
hold that this cannot be economically
justified, although it 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 lIlul surface Oh Il COLI
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 eXces-
sive wear on portions of the concrete.
For a. successful concrete road. hard
! ness. t0ughneSs and uniformity are the
most essential qualities. These can be
secured to Il great extent by care in the
selection Of the constituent materials
and the proportions in which they are
mixed. The cement, if is said. should
always conform TO some standard sppc
ifcatfons for portland cement surh
as those issued hv the United States
bureau of standards or the American
Society Fer Tpsting Materials The
sand should not contain more than 3
per cent of FOREIGN matcriaI. and sand
with more coarse than fine grains is TO
he preferred. The coarse aggregate
may consist of either crushed stone or
gravel In either case if is very deeira-
bic that the coarse a~grponto Nc well
graded in size between prcprr limits
The proportion Of cement 70 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-haIf 70
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 sand
to three parts of gravel When crush.