The sun. [volume] (New York [N.Y.]) 1833-1916, 1892-06-26
NEW ronx ASPHALT pArEMtx1s
TIE Principal Material Comes from . Lake
OF piteh on Trinidad Island.


| Asphalt paving has been subjected to care.
| fu and extensive examination under the d.
rection OF Commissioner Gilroy Of tho Do.
partment OF Public Works. tho need OF clean,
smooth and noiscless pavement In streets oil
light traffic having been fully appreciated.
Tho requirements limit tho choice to wood
and M phalt. and. as the experience with wood
paving from 1866 to 1872 showed that wood
is unsuitable to tho conditions OF our climnto
and traffic. attention was directed almost
solely to asphalt II Is admitted that for
heavy traffic granite blocks on proper
foundations form the best pavement. Whom
It was decided thrco years ago to uso asphalt
paving in streets of light traffic, tho Commits
sioncr took advantage OF tho experiences OF
European cities In using rock asphalt and OF
Washington and Buffalo in using Trinidad
asphalt Out of siStyfour streets that have
been paved with asphalt in tho pnst three
years. nity.six have not required repairs. four
needed somo repairs. and four proved to be
bad in spite OF repairs. the material having
been unsuitable. Tho bad pavement was re-
ncwed subsequently with proper material.
The standard test OF asphalt at first was the
purity Of the bitumen. but experience showed
later that other properties and qualities were
required to make the best Asphalt. The use
of cid stone block pavcmcnts as foundations
for asphalt surface has been successful. 1t Is
cheaper than to remove the old pavement and
lay concrete foundations The Commissioner
said in n report to tho Board OF Estimate and
Arporionn,ent that the old pavement ,, pro
without risk, OF shrnkaGe In tho ioun,,
iati"n; which has become settled and
Of nature, and that the asphalt pavement
can be laid exrehitiously and without the de-
lays and otstructions that are caused when
n n al, n M ~ -
r"adbcd cxcavntcd and graded. His conelu-
siuns arc that. except in few instances the
pcrtaton and requirements, that no other
known pavement combines 10 the same de.
Er,s tho o r,lTstSs tor Residential streets
of maintenance for fifteen years. is less than
the, original cost of 4 granite block pavement.
and that the pavements are laid and main
tanned in this city ~ IL cheaper rate than those
laid in any OF he European cities.
After ii had been discovered that the pave
mcnts IN fUur Of the streets were unsuitable,
the Commissioner decided to investigate and
tcst materials more thoroughly, and he sent
Of the West India islands. to inspect the
asphalt lake there and examine the deposits
and method of mining. that being the chief
source OF supply. report OF tho investiga-
ton WAS submitted recently. and it contains
facts that should be interesting to everybody
Although asphalt is found in different parts
OF Trinidad. 1t is found in sufficient quantity
for commerce Or Of quality suitate for street
THE ritchi. where tho wonderful Pitch Lake 10.
with deposits q iron pitch and land pitch. so
the sea at an elevation Of 1873 feet It's area is
about li5 acres. and its shape is almost cir
direction; sufficient to drain OF raintails
s % all fT nfh rfssu isGm ov t1e
and srs separated by ehannes Of water Few few
in WI. IL md fn1 In in
eral small islands comprising from fifty to
sixty acres are scattered over the surface with
growth Sn Of op lz 20
The color Of the uke is dark chocolate brown.
and Eneineeerl rowIe says thatlit looks like q
pressed closely together and separated only
by the narrow channels. of water.
IN sn"i he s1t set the
rs Boiling Spring. The appearance of builin.
is due tothe escare of large volumes OF sui
Violently. The notion that the
spring IL the source Of supply i, erroneous.
Mr. I9wle says. 1t is the last Of the asphaltic
deposits. and Is ages more recent than the de-
posts known rs iron pitch and land pitch on
the SLOPE Il, and more recent than The solid
I ofm th liz 'a aepos fs
outside OF it. biologists differ on The
Ge IN fes Gsrhas found an rG
The local Government biologists believe that
I he asrhalts are Of vegetable origin and are
A.,
most biologists agree with them. Others as
sert that the asphaIts are of volcanic origin.
and some believe that tho source is to lie found
where vast deposits have been found.
The lakes surface can support the weight of
to depth of about three feet. loaded into
carts and hauled to the shore for shipment
4 singular pecuiinrty is that the pits made
Is due to the great viscosity OF tho asphalt.
DISTINGUISHING It from the other deposits on
hs o tine Sas ge the
and land ,pitch.with covering Of earth several
Ieett in drpth TINT SUPPORTS dense tropical
village OF La Bren rest on the pitch. The
asnhass forming the deposits vary in color
rom graft to LIaek. Iron pitch is hard. brittle.
anu almost black in color. and IL in compact
masses of detached deposits. Land pitch has
more or less dirt and foreign matter and varies
kinds Of asphalt can be mined in the village
streets and plots. II n yllnger does not care
70 T" L Tor ;Gpmeb9dy else 9 can 20 out Of tho
Iard. Perhaps he can make enough that way
q live on; il not he can find plenty OF work on
he deposits being on both sides Some vii
ayers have become rich enough to own sew
,r Gts tnat they Lease to Others The
almost exclusively to tho nitsd States. Wien Wien
md lthcm. Only the angles and prol t ito as
ire rOunutd OH ana Soltened by the sun.
According to an analysis OF samples OF tho
deposits the difference in the bitumen is g. 30 |
per cent. the difference in the soitcning points
icing as great rs 500. In nsphaiti" oil tho dif-
creme" is 3US por cent. Tho differences are
n favor Of tho lake asphalt. which requires
ne addition o! less resiiuum oil in tho prepa-
alton OF nsphaltic cement for pavemcnts.
Lake asphalt is tho standard required BY the
'pecliications 70" asphalt pavcments in Wash
ngton. and Engineer Towle suggests that it
DO made the standard Of quality in this cit "
Asphalt. heinga nOn-nbSortent material, is
or sanitary reasons an excellent pavement
IN wet weather horses wnr" liable to slip on ii.
As !prmrry constructed. but tlint defect has
Jcrn rrm%died in m"a.urc The surface
eng slightly elastic. the limbs OF horses re,
paving Trinidad asphalt is mivcd with other
materials. For New York uaver,cntS an us.
'ha'ir cement is manufactured. composed OF
lshhalt and petroleum OH in the proportion OF
l0J laris OF asphalt TO 10 or 20 parts Of
,,!h,ed 10, TO 80 ,rarts Of fine sand
ND . tc 10 parts Of pulverized carhonata
u lime. The sand and cement are heated
to about 3UU' The Carbonate OF |
imc. while cold. is mixed with hot sand, and |
1oth are combined with the cement ut the re- |
lnred temperature. Tho mixture. when ut n |
OF ZOO Is spread over the founda- |
ion 70 such depth that after compression il |
sill have thickness Of two inches. The sur.
on nrnS sal