The Washington herald., 1922-05-17
ROAD TESTS PLANNED
AT ARLINGTON STATION.

A comprehensive program of road
building research and Investigation
during the coming season at the
Arlington Experimental Station
near here has been announced by
the Bureau OF Public Roads. Inn
pact tests on pavements, subsrsde
studies and other experiments.
which last year aroused much in
terest among engineers. will be con-
tinued as well as several other
lines Of work under way last year
and new ones to be started.
Bituminous wearing surfaces are
TO be Investigated to determine the
reason for the formation of waves
and irregularities and TO settle
mooted questions concerning the
proper mixture and the proper min
ersl aggregates to be used in BIZ
luminous roads. More than thirty
sections Of different types Of BIZ
luminous construction will be built
These will include mixtures of diff
ferent mechanical grading and with
different percentages OF bitumen of
several degrees OF hardness. Sec
tions are being constructed on a
circular track about 500 feet in cir
cumferenee. the roadway being
thirteen feet wide. On this road
way will be operated a ive-ton
army truck equipped with solid
tires. The truck will be operated
in a varying path 30 as TO cover
practically the entire width OF the
roadway and will travel at a speed
OF from twelve to ffteen miles an
hour for 1--WE or six months. or un-
til some results are obtained lead
ing to the solution of the problems
involved
There is considerable discussion
as to what is the proper criterion
to be used in selecting and judging
( concrete aggregates that will offer
the greatest amount Of resistance
10 wear. At the present time tudg-
ment is based on wear tests made
in the laboratory ana upon the
compressive strength of concrete
/ also upon the structural strength
of concrete beams constructed and
broken in the laboratory. The
comparison Of the wear Of concrete
/ in actual use on road surfaces with
the indications obtained In lahora-
tory experiments is not wholly sat
isfsctory.
To throw more light on this sub
ject a wear test IL TO be made with
4 the conditions approximating those
actually found on the road. This
test will include about siIty-nve
sections Of concrete wearing sur
face. each section being OF differ
ent quality of concrete. the quail
ties being varied by virtue Of the
different aggregstes used. different
proportions in the mixture and
amount OF mixing water. These
sections are to be constructed on q
circular runway about ESQ feet IN
circumference. the runway being
four feet wide.
On this runway will be operated
a specially constructed car with
1.-TWO truck wheels equipped with
solid rubber tires and loaded to
represent a truck. The car will be
guided by small railroad rails %
hold II in position. the power being
applied by means OF an slectric mo-
tor to the rear wheel. This sp-
paratus will be operated around the
circular runway at a speed OF prob.
ably twenty miles an hour. tn,
test will involve the use of truck
wheels equipped with different
kinds of tires and will incluos the
use Of nonskid chains.
The object OF this experiment Il
to determine the relative wear oi
the different concrete sections whes
subjected to trsfic equipped will
different types OF wheel. slse Z,
: furnish a comparison between as
tusl service conditions ana lseora
tory tests This test will be in op
Grafton continuously. beginnini
some time in June.
J Among the $50 different kinds o
bacteria and other organisms tskei
J from the bodies Of house flies b,
different Investigators are inrantil,
diarrhes. typhoid fever. anthrax
food poisoning. smoebic dysentry
abscesses, leprcsy, tape worms. heoi
worms, bubonic plague, conjuneti
: Wits, summer complaint. tuberculo
sis. eonorrhes, green pus, enteritis
trachoms, erysipelas. gas eanerens
stomach worms, pin worms and oph
thalmiA
W. d