Evening star. [volume] (Washington, D.C.) 1854-1972, 1868-06-08
How to Make Concre,. for Bui,diry

Judging from the fact thar concrete walls
have been made 10 answer a satisfactory pur-
be erected again, II the materials are only OF the
best quality The correct way 10 make can
crete Is 10 mold the sand and lime IN TASKS and
dry the blocks under shelter for nearly one
year before laying them In a wall. For an or
binary two or three story dwelling house the
walls OF the two lower stories should be not
less than one foot thick. The upper stories will
be comparatively strong with the lower ores III
the walls are made only eight or nine inches IN
thickness. More than this, il the wall OF the
upper story be only eight or nine inches thick
The superlncumbentpres will be less on the
walls Of the lower story than IL the work were
made one foot thick to the top of the building
When about 10 erect a concrete building, a
builder should have perfect understanding
OF what is required, as Experiments with this
maternal are someumes disastrous and enor-
mously expensive.
In making concrete blocks. il is far better TO
mould them Of size suitable for one man TO
laid by one man, some Of the corners Will h.
Knocked on almost every time a block is lad
d ,wn. For this reason let the moulds or TASKS
be made Of hard, smooth wood, one foot wide,
SIX inches deep, and not over one-and -a-half
feet long. III any part Of he wall Is to be eigh-
teen inches thick, the blocks should be nine in
ches wide, six inches thick and eighteen long,
so that every fourth course may be laid cross
ways Of the walls, for the purpose of bisdIur
the courses beLeafh IL.
The proportion Of lime. cement and sand will
is assumed that the lime is Of the frst quality
and not Stacked until il is mingled with the
sand. Then, one bushel Of unslacked lime, six
OF sharp sand and small gravel. with half n
peck OF prime cement. Will not fail 70 make
concrete blocks that will b. almost like stone
Builders understand the importance of putting
cement mortar in the place, where IL IL TO re-
mann, as soon as practicable, after the material
has been Wet up and tempered. IL IL quite inn
portant that common stone lime he mingled
with he sand and gravel. and that the mass BE-
tempered and moulded as soon as practicable
after the line ls slaked. The sooner the work
can be performed, the firmer the concrete
blocks will be. Let the plastic material be put
into the mould as stih as il can be worked con-
veniently. II AZ Were 80 stiff that a rammer is
necessary TO NIL the mould. all the better II is
desirable 20 employ large number of TASKS.
when forming the bloc Ike, in order to allow th.
concrete ample time 10 set a triie before the
blocks are turned out of the mouIds The
blocks are moulded and the surface stricken on
true, similar 10 the process Of making clay
bricks. TIE slaked lime, cement, sand aud
gravel, ought 10 be m ingled thoroughly, befor.
any water is added. Then temper only q few
bushels at once. and NIL the TASKS before any
part OF the concrete has time 10 set.
ne object of work king in this manner is 70
secure the full advantage Of the first setting Of
the common lime. Common lime may be wet
up, the water poured of, and il will set in n
few minutes. The next day the same lime may
he render plastic again when il will soon set
again. This process may be repeated several
times. But every time the lime is allowed 70
set II loses what we call its strength. or is
power 10 solidify. Consequently we NAV
make concrete blocks with lime Just Stacked
which will be almost like stone. and we NAV
make other ole ks with lime of the same
quality, after u hiss been sair-slacked." or al
lowed 10 set several times, after having basu
tempered. and the later blocks of concrete will
sometimes erumbie to powder like blocks made
of sand and ashes.
Blocks Of concrete will require long time To-
solldify. The surface will seriously deceive a
superficial observer. A shell mr. tu-o inchas a.,
thickness may appear exceedingly compact,
while half OF the interior of the block has not
yet passed the condition spoken of by masons
as "the tender state OF mortar " Every block
should have all the time that is required 20
render the middle quite as solid as the outside
Then concrete Will be about as durable as
stone. II the blocks are allowed 20 lie exposed
70 the rain, longer time will be required To
dry them, and the material will never become
as solid as it had been dried under sheIter-I
Edsoards Todd iR Nec Tork Hmes