The Caucasian. (Shreveport, La.) 1900-192?, 1903-06-07


The cement for the concrete must be
of standard grade of Portland or Hy-
draulic cement, newly manufactured.
The cement while in storage Or upon
the work. or while being hauled 20 the
work. shall be properly protected and
lno cement shaft be used which in the
lopinion OF Che city engineer mas been
damaged by age or exposure.
Cement used aluse stand 6OAowno
tests:
Fineness-Siese No. ps % 10000
meshes per square nch OF No. 40
Stubs wire gauge: Portlana O. Ger
cent fine: Hydraulic SO peg cent fine.
Specific gravity-Samnie weH dried ::
Portland $40 20 a.2S: Hydraulic 900.
| Soundness-Pass ID ue;a ce1nerR J
inches in diameter /. inch at center
with thin edges: Port'an9 homs bolt
| ing test Hydraulic must nOs crack or
become contorsed along edges IN two
days
! Time iof Sutherland initsas set As
minutes, hna1 seq 10 hours gtvdraulic
initial Sc, - minutes; &nsf set 10 hours
! Tensile strengthened briduettes,
strain applied uniforms rate Q ~ 400
pounds per minute: Portland . day G25
pounds, = days ago eounds; Rydrau,ic
day Is pounds. : days ~; pounds
Twill be laid the binder course somposed
men, The brohen stone nust be equaf
in quality 20 the stone specife& TOR the
concrete base. the fragments varying
| half inch on longest diameters.
h-o1 Sa AaX NSN n
temperature OF not less than ESQ or
thoroughly mixed with as hattie &C.
ment, of the quality specified for The
pavement. at temnerature of from as
to 325 degrees Fahrenheit. the frag
ments of stone to be perfectly coated
with the asphaltic cement in sufficient
quantity to bind them firmly together
when the mixture has been spread upon
the concrete base and finally COM
pressed Should the binder appear dull
from overheating or lack of cement. it
will be rejected
This mixture of broken stone and as
phaltic cement, while hot, will be hauled
upon the work and spread upon the con-
crete base to such depth that when thor
oughly contacted it will give a uniform
thickness of one-half inch. AS soon as
it is spread, and while in hot plastic
condition, the binder shall be compacted
by rolling with roller operated by
steam power and giving weight press
ure of not less than Us pounds per lin
cal inch of roller. Such portions of the
binder course as can not be rolled will
be thoroughly compressed by ramming
The concrete base shall have firmly SET
and shall have dry surface when the
binder is placed upon it.
The surface of the binder course shall
be made exactly parallel with the re-
quired surface for the finished pave
ment. and the fragments of broken
stone, throughout the entire course,
firmly bound together.
53.-Wearing surface: Upon the bind
er course will be laid the pavement or
wearing surface, composed of asphaltic
cement, sand, and carbonate of lime.
The asphaltic course will be an admix-
ture of asphaltum and heavy petroleum
oil
The asphaltum used will be refined
from the best quality of crude asphalt
tt1In, obtained from the. pitch lake in the
Island of Trinidad, or from the pitch
lake in the State of Bermudez, in the
Republic of Venezuela, South America,
or from the Alcatraz mine, Santa Bar
bara County, California.
The asphaltu1n must be refined, and
SO far as possible freed from all foreign
organic matter and volatile oil, and
must contain at least sixty (oo) per cent
of bitumen soluble ir bisulDhide of car
bon.
The petroleum oil must be freed from
coke and Others impurities, and brought
Ito specific gravity of from IS to ~
degrees Baume, and fire test of 900
degrees Fahrenheit.
The refined asphaltum and the heavy
petroleum oil will be melted and mixed
in the following proportions by weight,
to form the asphaltic cement, viz: Re-
fined asphaltum 100 parts: petroleum
oil from II to Is parts
The sand must be reasonably clean,
hard grained and sharp, said cleanness
and sharpness to be determined by the
city engineer, and of such a degree of
6neness that thirty (3o) per cent will
pass No. So screen, and all of it will
pass No. 20 screen.
+ The carbonate of lime will be in the
form of a powder produced from clean,
sound limestone of such degree of fine
ness that sixty (oo) per cent by weight
will pass a No. 200 screen, and all of it
will pass a No. so screen
The asphaltic cement prepared in the
manner specified will be mixed with the
sand and carbonate of lime in the fol-
lowing proportions by weight, viz: As
.phaltic cement 10 to 16 per cent; sand
80 to 70 per cent; carbonate of lime 10
to Ia per cent.
s4.-The following method of pre-
pairing and laying the pavement compo-
.sition or wearing surface will be OBJ
served:
In order to make the pavement homo
genous, the proportion of aspflaltic ce-
ment must be varied within the limits |
specified, according to quality and char
aeter of the sand. The proportion Of
carbonate of lime NAV be reduced when
the. character Of the sand will permit
The sand and the asphaltic cement |
will be heated separately to about 800 |
degrees Fahrenheit. The pulverized car