The Barre daily times. (Barre, Vt.) 1897-1959, 1915-09-04
CONCRETE ROADS.
Growth in Popularity Indicated by Rapid
Increase in Mileage in Recent Years.

y
q Increase in Mileage in Recent Years
The mileage of concrete pavements il
the United States has increased rapidly
and it is likely to continue to increase
according to new bulletin of the de
partment. This bulletin gives the es
: timated amount of concrete pavement
: in the United States in 1914 as l9,200,
600 square yards; in 1909 it was only
$4,000 square yards.
The principal advantages of concrete
payements which have led to this in
crease in popularity are said to be:
|. Durability under ordinary traffic
conditions.
?. A smooth, even surface offering lit
tie resistance.
3. Absence of dust and case with
which it may be cleaned.
4. Comparatively small cost of main
tenance until renewals are necessary.
5. Availability as base for another
type of surface if desirable.
6. Attractive appearance.
In commenting upon these advantages
the bulletin states that the durability OF
concrete roads have not yet been proved
by actual practice, because there are
no very old pavements as yet in exist
enee, but from the condition of those
which have undergone several years
service it seems probable that they will
be found TO wear we'll
The disadvantages Of concrete as road
surface are:
| !. The noise under horse traffic.
2. The wearing OF the necessary joints
in the pavement, and the tendency
TO crack with its consequent rapid de-
teriorstion.
3. The difficulty of repairs when these
become necessary.
In the past efforts have frequently
been made to overcome these objections
TO certain degree by covering the con
crete pavement with a bituminous wear
ing surface. At the present time, the
specialists in the department hold that
this can not be economically justified,
although it is possible that future in
vestigation may change the situation in
this respect. In the present state of
road science, however, il seems that
where traffic conditions are such that
bituminous surface ON concrete road
is practicable a bituminous-s surface ma
cadam road would be equally practicable |
and certainly cheaper. Where traffic IL
too heavy for macadam road the bitumi |
nous surface is likely TO give way and |
the uneven manner in which ii fails
tends TO produce excessive wear on por-
tons OF the concrete.
For a successful concrete road, hard
ness toughness, and uniformity are the
most essential qualities. These can be
secured 20 a great extent by care in the
selection Of the constituent materials
aud the proportions in which they are
mixed. Sample specifications are in
cluded in the bulletin. No. 249. Portland
cement concrete pavements for country |,
roads, These specifications are believed
TO typify the best engineering practice
IS il has been developed 20 this time.
They cover such points as materials,
grading, subgrade, and construction.
The cement. IL IA said. should always
conform 20 some standard specifications
'or Portland cement, such as those is-
'ued BY the United States bureau Of
standards or the American society for
.esting materials The sand should not
.ontain more than three percent Of for
IGN material. and sand with more coarse
rain Is 90 be preferred. The coarse !
aggregate may consist Of either crushed
tone Or gravel In either case Il Is very
desirable that the coarse aggregate be
veil graded in size between proper lin.
e. 4
The proportion Of cement 70 the sand /
nd coarse aggregate combined should &
.ot be- less than about one 20 Eve, and !
Ne proportion 81 sand 20 coarse aggre- 4
ate not les than one and one-hslf 90 a
hree, nor greater than two 10 three. A \
seful formula when gravel is used ~ 4
oarss aggregate Is one part Of cement =
p one and half parts Of sand 20
hree parts Of gravel When crushed :
tone is used. one and three f0urths
arts n sand may h. substituted IN
lace - one and onr-hah parts A
De- addition O. discussing the enqi-
ssrinq details Of construction the bal
tin already mentioned calls attention
: fhs fact thst ordinarily from one
bird - one half ~ ths total cost - c1n-
'raetinc q concrete pavement Is for D.
nr after the materials are delivered
bic emphasizes the Importance 81 Ell
snt organization and pFcpof equipment D
E fiurs 90 take thess faftors INTO oou-
AeFatiun fre4neutlv results. i j. said.
aadug from Zen to - rfr esrt a.
y fast rf q eslarete pavement &
TIE most ecrnuuia1l method De- a. =
srs tie work - MINING and placing an
,uarsts as meaflV rrnfimupus ~ pratti-
tls The w-ufk shpuid - PLANNED whh
rr5marv Fieu IF keeping the uiiner
ing fun tfuf The frainzrr strur-
ifas ths ersdlnr ard tis sHl.rFadsI
.uu1a therefore ~ eanFsletsd sell u
itnuss ef tss tuirrr anl IEotisiss mae
p nassfrirr sH a Ia uraessarr mat
isis uIfhaat dsiav ~mm1n error /.
fhs fniiure e maks sae9uats r-e4is !
n fnr delivering wutHf On thf wufE :
u 80 nnruurf utist efFHn stsasns fs {
1as1s II Supplying = Frequently over
{ uasaf
So A. r. ia