Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1915-07-07
BI1vlnH,c aspHALrlc CONCRETE

| about as much about paving processes
as some man interested in paving ma
terial will tell it, objects to the Times
bitulithic paving. The T.-R. stated
! that Grinnen had very good quality
of what the engineering profession
&, calls asphaltic concrete but that Grin
nell had paid useless and big
i bonus for a process controlled by a
patent Now the Herald comes back
with the charge that the people Of
Grinnell like their paving even at its
high price while the people Of Mar
shalltown have a worthless paving at
a cheap price.
Grinnell people have never had a
chance 10 try any other paving. hence
II is not strange that they should like
what they have. For half the Grinnell
cost Marshalltown people have paved
with what they think is good paving
and they are laying more of it this
year. But lest the Grinnelf paper
should continue 10 believe that the
T.-R. does not know what it is talking
about in calling bitulithic an asphaltic
concrete let's consider the specifca-
tons.
Bi-ulithic uses a concrete base and
so DO almos, all good pavements There
is no patent or monopolistic control Of
the concrete base. The niger is In
the wearing surface. In bitulithic this
wearing surface is two inches thick;
Composed OF carefully selected,
sound. hard. crushed stone. mixed with
bituuen. After heating the stone to
TEN peyature of about $50 degrees il
shall be passed thru a screen with var
ious sized openings. If the crushed
stone in the wearing surface does not
provide the best proportions Of fine
grained particles such deficiency must
be supplied by the use of not to exceed
% per cent hydraulic CEN ent, pulver-
ICED stone or very fine sand. In this
mixer shall be added sufficient guam
tity of Warren's Puritan Brand No q
Bituminous Waterproof Cement or BIZ
tulithic cement to thoroughly coat all
the particles OF stone and to fill all the
&
cement shall before mixing with the
stone be heated TO between 200 TO $50
degrees and the amount used shall be
in such proportions as 10 coat all par
ticles OF stone and fill the voids in the
mineral aggregate"
! In Chicago the city park boulevards
have been paved quite extensively With
Sarco What is Sarcoo Why 1t is an
other name for asphaltic concrete put
Asphalt and Rubber Company. The
initials OF the firm name spelling Sarco.
1t has been a good pavement, too, but
does not infringe on Bitulithic, SO COM
pare Sarco wearing surface with Btu
lithic. Sarco specifications call for:
The Sarco wearing surface shall con-
sist Of a two-inch layer of clean, hard
crushed stone. fairly evenly graded as
to size combined with q definite pro-
portion Of sand and thoroughly inter-
mingled with g filing and elastic sub
stance consisting OF Mineral Rubber
Asphaltic Cement The proportions
shah be So per cent by weight OF
crushed stone IS per cent Of sand, g
per cent asphaltic cement TIE Min
eral Rubber -Aspilaltic Cement is used
TO fill the remaining voids to bind the
mineral particles together. When the
stone and sand are thoroughly dried
and heated to temperature of from
$50 to 300 degrees they shall be imme-
diately, before cooling or exposing to
moisture, mixed with the Mineral Rub
Der Asphaltic CEN ent melted and raised
to temperature of 800 degrees com
bined with the hot sand and stone and
| Immediately mixed.
| Sarco, like Bitulithic is controlled
and contractors compelled to use the
| controlled material and mixture must
pay the price exacted by the company
enjoying control. That is why Grinnell
pays this year nearly $500 per yard
for aspha1tic concrete which should not
cost to exceed $3.50 on an open speci-
hcation. But the Grinnell Herald has
been told by somebody that open and
free Specifications for asphaltic con-
crete is bastard stuff" Now who
cares as to the parentage Of paving?
It's the stuff that counts so listen to
the specifications for open asphaltic
concrete as laid in Baltimore.
| After the concrete foundation has
been laid a two-inch wearing surface
shall be laid, composed of one-inch
crusher run trap rock varying in size
from ~ inches down to dust, no piece
OF stone to have a greater dimension
than IN inches, the stone to be KEEP,
dry and free from dirt The stone tc
be charged into the mixing device and
after it has become perfectly dry (by
heating). per cent OF asphaitio oe71ent
at a temperature Of 290 to 325 degrees
shall be added and the mixing shall
continue until the contents is uni.
form bituminous concrete and each
stone thoroughly coated.
That is aspIialt;c concrete so caffe,
by agreement at the national conven.
; tons Of engineers. Wherein is the dit.
ference between any two of the three
mixtures? They all use hard stone O.
varying sizes for an aggregate, SAND
to fill the voids and bitumen to thor.
oughly coat the particles and cemen
them together. Other engineers will
vary the proportions slightly but al
obtain hard stone concrete cenentef
with bitumen.
. Tho difference is in the material ON,
, viii say. Let's see.
Bitultthic specifications are silent a:
To the pualitv Of hifuyY,ep ovcapt .h..