The Adair County news., 1913-12-10

~
start has been made with frame build
ings.
Concrete is as cheap as lumber for
building purposes and even cheaper if
sand, gravel and labor are largely fur
nished on the place. An ordinary
farm hand will become expert in the
use of concrete with few days ex-
perience.
SiloS, barns and other buildings
made of this material are much safer
than wood against fire and storm.
The largest part of concrete is the
gravel or crushed stone. This should
be clean-that is, free from loan, clay
or vegetable matter. The best results
are obtained from a mixture of sizes
graded from the smallest, which is re-
tanned on a one-fourth inch screen, to
the larger ones that will pass a one
and one-half inch ring. For heavy
foundation and abutment work larger
sized pebbles and stones might be used,
while for REINFORCED concrete work
pebbles larger than those passing a
one inch ring should not be used.
In the selection of sand the greatest
care should be used, and critical atten-
ton should be given to its quality, for
sand contributes from one-third to one
half of the amount of the materials
used in making concrete. Sand may
be considered as including all grains
and small pebbles that win pass
through q wire screen with one-fourth
inch meshes, while gravel in general is
the pebbles and stones retained upon
such a screen. The sand should be
clean, coarse and, if possible, free from
loan, clay and vegetable matter.
In mixing materials for concrete use
two and half times as much sand as
portland cement and twice as much
gravel or stone as sand-that is, one
part cement, two and a half parts of
sand and five parts Of gravel or crush
ed stone. Use just enough water to
get the consistency desired. If the
sand is very fine the cement should
be increased from 10 to 10 per cent.
When the mixture does not have Il
uniform color, but looks streaky, 1t has
not been fully mixed.
If the mixture does not work well
and the sand and cement do not fill the
voids in the stone, the percentage Of
stone should be reduced slightly, but
the concrete should first be properly
mixed. Concrete that is poorly mixed
may present features that are entirely
eliminated by turning it over once or
twice more.
Concrete wet enough to be mushy
and run off a shovel when being han
died is used for REINFORCED work, thin
walls or other thin sections Concrete
| Just wet enough to make it jelly-like
Is used for some REINFORCED work and
also for foundations, floors, etc. 1t re-
quires ramming with tamper to re-
move air bubbles and to fill voids.
| This concrete is of medium consist
! ency. n 80. s555l:-sZsss..
Sometimes bank or creek gravel,
which will answer the purpose of sand
and gravel combined, can be obtained,
and it is frequently used on the farm
and in small jobs Of concrete work
just as it comes from the pit or creek.
Occasionally this gravel contains near
ly the right proportions of sand and
gravel, but in the majority q sand
pits and gravel banks there Is a great
variation in the sizes of the grains and
pebbles or gravel and in the quaint.
ties of each. This is due to the fact
/ that all the deDoSitS are formed I'm
seams ror pockets that make it impos.
sible| ITO secure anything like uniform
ity. Therefore, to get the best and
cheapest concrete it is advisable to
screen the sand and gravel and to re-
mix them in the correct proportions for
the work.