Keowee courier. [volume] (Pickens Court House, S.C.) 1849-current, 1922-08-23
Device Testing Measuring Of Roada

prepared by tho United States Department
q OF Agriculturo.)
A comprehensive program OF road
building research and investigation
during the coming season at the Ar
lington Experimental station near
Washington, D. G., is announced by
the bureau Of public roads Of the
United States Department Of Agri-
culture. Impact tests on pavements,
subgrade studies and other expert
ments, which last year aroused much
interest among engineers, Will be con-
tinued as well as several other lines
Of work underway last year and new
ones to be started.
Bituminous wearing surfaces are to
be investigated to determine the rea-
son for the formation Of waves and
Irregularities and to settle m0oted
questions concerning the proper mix
ture and the proper mineral aggregates
to be used In bituptnous roads. More
than 30 sections Of different types Of
SbituminOus construction will be built.
These will include mixtures Of differ
,ent mechanical grading and with
different percentages Of bitumen of
several degrees Of hardness. Sections
are being constructed on circular
track about coo feet in circumference,
the roadway being ID feet wide. On
this roadway will be operated a g.
ton army truck equipped with solid
tires. The truck will be operated In
varying path so as to cover practically
the entire width Of the roadway and
will travel at speed Of from 12 to
Us miles an hour for five or six
months or until some results are OBJ
tained leading to the solution Of the
Epr0blems involved.
Resistance to Wear.
There Is considerable discussion as
to what Is the proper criterion to be
used in selecting and Judging concrete
aggregates that will offer the great
,est amount Of resistance to wear. At
the present time judgment is based
on wear tests made III the laboratory
and upon The c0mprcssivc strength or
Eooncretc, also upon the structural
strength of concrete beams constructed
and broken IN the laboratory. The com.
paris0n of the Wear OF concrete In
actual use on road surfaces with
the indications obtained III laboratory
experiments Is not wholly satisfac-
tory.
To throw more light on this sub
5ect wear test is to be made with
the conditions approximating those
actually found on the road. This test
win include about 05 sections Of con-
crete wearing surface, each section
being Of different quality Of con-.
crete, the qualities being varied by
Virtue Of the different aggregates used,
different proportions in the mixture
land amount Of mixing water. These
sections are to be constructed OH
|circular runway about $50 feet in cir
cumference, the runway being q feet
wide.
On this runway will be operated a
specially constructed car with two
truck wheels equipped with solid
rubber tires and loaded to represent
% truck. The car will be guided by
small railroad rails to hold 1t In posi-.
!tion, the power being applied by means
|of an electric motor to the rear wheel.
tThis apparatus will be operated around
lSuo cACuiuf runway at speed or
probably 20 miles an hour. The test
will involve the use Of truck wheels
equipped with different kinds of tires
and will include the use of non.skid
chains. A steel-tired wheel will
probably also be used to get the effect
of an accelerated wear test
! Tho object Of this experiment is to
determine the relative wear Of the