The central record. (Lancaster, Ky.) 18??-current, 1922-08-03

different concrete sections when sub
icctrd ~ traffic equipped with differ
rut typc~ II wheel. also 'o furnish
comparison between actuul service
conditions and laboratory tests This
test will bc In operation continuously
beginning some time IN June.
impact on Roads Studied.
IN a rather elaborate series ~ ex-
perimcnts. the bureau has studied i'm
pact - trucks uu roads, and has lie
termIned approximately the magnitude
~ Impact furce under different truck
aud road conditions The effect -
such Impact "a concrete paNemenis
and several types II read on coOcrete
ha,. was studied aud reprr'sd "a last
year. This series If experiments Il
tu h.. continued and enlarged over
~ road sections ,r slabs have been
constructed In duplicate series. one
series j. 81 carefully drained dry
,uhgrude the other series j. on the
same kind ~ suhgrudo except that 10
Is kept Wet and a. nearly saturated
~ possible by means If an underlying
/ drain tile and side ditches filled with
water
The testing of these slabs will be
gin some time during the month u
/ Nlny aud will be- by means II a new
Impact machiu. now being constructed
, which Stimulates the action 81 the rear
/ wheel Of truck ON this maChiIx
may be mounted truck wheels ~ differ
I .ui sizes and weights carrying differ.
,ut kinds II truck tires This APP
I paratus may be- 80 operated n 20 re-
l produce the different loading and
equipment conditions of a large variety
/ 81 trucks The siuh, will be hammered
/ hy means IT this machine .u the center.
on the corners ard IN the sides 50
o., 20 obtain the relative strength un-
/ Ter these different conditions.
/ Suhs"il inNestl -atiuus are being con
iinurd for the purpose - studying and
| investigating relative stability m"is-
lure condition. 'aud supporting value.
Different methods of determining the
bearing value ~ soils are also helm,
studied. that l. ~ "a whether small
90 large ar-a> should be- used in de.
tcrmining the r,Iaii,, bearing value.
The wurpiug effect 81 temperature
aud moisture conditions ou concrete
paNcments j. also being Investigated
Temperatures ami movement are being
recorded graphically ON continuous
charts In addition 10 these tcmpera.
turr and movement measurements the
prcssurrs on the .lhgrade under the
concrete slab ar" uhtuined BY means
~ soil pressure cvlts. This inVcstiga-
tion will give some definite information
concerning the support offered 10y sub
grades tu rigid concrete roads This
Investigation has been under way Tor
some time aud viii continue probably
for year or more.
The transmission % loads through
different types 81 payements o. the
subgrade il being Investigated by
mcaus uf soil pressure cells placed on
the subgrade under the payements.
This test will also serve To show the
relative support offered o. brick and
other types 81 block payement'b by con.
crete bases and broken stone bases.
This Investigation has been under way
for about one year and will continue
for some time to come.
A large number ~ prominent engi.
neers aud others Interested in road
work have visited the Arlington IN.
perimental station Ia witness the prep
aration aud conduct Of these expert.
ments. Il Is intended Ia have all these
proJects In full operation by the mid.
die of June. Visitors are always well
come and those Ia charge Of the work
are always glad Ia give any informa,
tion desired about the experiments