Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1911-03-16

stone SnOulo vary III SA1v AAosN HAeSSs
ono inch in diameter to sand grains.
BY 80 sradins the stone, the smaller
particles at in the spaces between the
larger pieces, thereby producing the
most compact and the strongest mix
! ture.
The best stone for crushed rock Is
one which is clean, hard and breaks
with sharp angles. Trap, granate. ana
hard limestone are among the pest; the
use OF shale, slate, and soft limestone
and sandstones should be avoided. the
crushed rock should be screened on q
one fourth inch screen to remove the
fine particles. These small particles
should be considered as sand; and II
insufficient In quality to make the
prope: proportion of the concrete. AZ -
described later. enough sand should be
added to them to produce the required
amount
Well Graded Gravel Good.
Gravel well graded In Sizes Is at
least equally as good for concrete as
crushed stone Bank-run gravel. just
as dug from the pit. seldom runs even
and rarely has the right proportion OF
sand and pebbles for making the best
concrete The mixture most suitable
has one part sand to two parts gravel,
measured by volume, in which all sizes
passing thru one-inch mesh screen
and retained on one-fourth inch
screen are considered gravel. AS there
Is usually too much sand for the gravel.
it Is both advisable and profitable to
screen the materials and to reniix them
in the proper proportions. Gravel
; should have no rotten stone and should
he clean, so that the cement may ad-
here to it tightly.
Sand Must % Clean.
With dirty sand, no amount of ce-
ment will make strong concrete. Cen
orally sand is clean, but II not, 1t can
easily be washed by playing a hose or
flushing water upon thin layers of sand
placed on tight jointed inclined
wooden board. In size Of grain 1t should
vary uniformly from fine to coarse. All
particles passing one-fourth inch
screen may be considered sand.
Any good tasting drinking water Is
suitable for concrete.
Proper Proportions For Farm Work.
Such proportions OF three parts. as
1924. indicate that the concrete is to
be mixed l part cement to parts sand
to parts screened gravel or crushed
rock; and IA that it is to be mixed !
part cement to parts bank-run gravel.
For farm work the following proper
lions are most suitable;
For concrete necessarily waterproof
1924 or Ia.
For all other ordinary purposes
1:2A:5 or 80.
Using "Two-Me Board.
The size of the batch is dependent
upon the amount Of help and the di-
mansions Of the mixing board or plat
form. For work OF ordinary size suffi-
cient room will be had on a two men"
board. eight by fourteen feet, framed
soltdly and covered with one-inch stun
with tight joints the short way OF the
board. A wooden strip nailed around
the outer edges will prevent tho loss
Of LIQUID cement. For such a board
and the proportions designated above.
make the bottomless frame Of tho clear
dimensions a. follows: Six inches by
two feet eight inches, by three feet:
and six inches by two feet, six inches,
by four feet.
Labor Saving Factors In Mixing.
All the materials (slightly more
than the computed Qualities). should be
on hand before beginning the work.
They can often be hauled at odd times.
The sand and gravel or stone should
be piled 80 az
To cause the least amount Of wheel
Ing.
To make the mixing most convenient
to the water supply.
To allow room for the future location
Of the mixing board.
II the gravel does not need screening.
place a bottomless frame. previously
described for a IA mixture on the
mixing board and fill 1t level full with
gravel. Lift the frame, spread the
gravel slightly with the garden rake.
and upon It distribute evenly two bags
(the fun amount) Of cement. Set tho
frame upon the lsveled surface Of CO.
ment ana gravel and again I'LL Il in the
same way.
Mix Carefully With . Rake.
Remove the frame and spread the
entire mass by dragging It back and
forth with rake. Two mon, opposite
each other. then turn the batch with
the square pointed shovels. Again use
the rake. Keep turning until the ce-
ment no longer shows In streaks. until
the mixture has . uniform color. Throw
up the ragged edges and, with sprink-
ling can or hose with spray nozzle. ap-
ply water in quantity according to
special directions given later for each
particular kind OF construction. Turn
again and add SO much moro water a.
may be required. II dry streaks are
still evident, continue the turning UNI
til they disappear. With wheeibar-
rows quickly remove the concrete and
Immediately use IL In the work
II crushed rock or screened gravel 10
to be used, MI the bottomless frame
with sand ana distribute upon it two
bags OF cement. Draw the materials
back and forth with the garden rake
then turn, as described above, until the
mass has uniform color. Spread the
mixture so that two framefuls Of
crushed rock or screened gravel may be
placed upon it. Wet the mass and turn
az for bank-run gravel until each stone
IL coated with cement mortar. Remove
as for the gravel orcrete.
For the proportions Of 1:2h:b or l:6
the method OF mixing 10 the aame.
Since crushed stone Is more or less
porous, in dry hot weather 1t Is advis-
able to keep the stone pile wet or at
least to water tile stone rel! 80 =
stands on wheelbarrows ready for the
mixing board.
Placing the Concrete.
How Placed: After the concrete 10
properly mixed 1t should be placed At
once Concrete may be handled and
placed in any way. best suited to the
| nature OF the work, provided the ma
I