The Washington herald., 1912-03-20

classes of binding material. Recently
there has been q reversal OF opinion TO
some extent. Personally, IN connection
with mortars consisting principally OF
lime. / believe that the combination OF
magnesia with the lime reduces the en-
ergy of shaking, and consequent danger
of burning Of the lime In hydration. and
increases the setting process ana Ior
building purposes i prefer a lime con-
tanning magnesia: and the tests OF the
Bureau of Standards on Lines, which
confirm the result Of our own work. IN
dicate that when made into mortar mag
nesium lines give greater strength than
high calcium lines. II used to be COM
mon to specify that lines should be pure.
that is. containing little silica or aluminn:
such LINES would carry more sand and
work smoother under the trowel; In real
ily. the leaner lines are better. as they
Until recently the manufacture Of lime
has been carried on under very crude
conditions, the lime burners being. as a
rule, men OF little educaaon or tneoreuI- I
relying on the immediate local demand
for their market, and were operated m
termittently as the market required. The
limestone was placed IN the kiln, mixed
with the fuel the KILN lighted, allowed 10
burn out. and the lime withdrawn. This
condition prevails to a considerable ex-
| tent TO this day. with the exception OF
the intermittent ones
Chemists Direct Plants.
II is to be no:sd. however. that recently
capital in considerable quantities Is 60
\ ing into the lime business. and II Is now
being manufactured on a large scale. and
the product distributed throughout large
areas of the country. The leading lime
manufacturers are now. like the manu-
facturers OF cement. employing chemists
in the control OF their plants. and in re-
search work looking to the Improvement
l -
not but vitality affect the quality Of the
material Recognizing that under pres
| ent conditions II Is impossible to give the
material proper preparation on the work
/ the lime manufacturer Is beginning to ar
range for all preliminary % %treatment o. O.
advance. and aging IL. delivering on the
work a prepared material in the form OF
dry powder convenient for use. The
pictures on the screen Illustrate the diff
fe-ences between the typical plant of q
| few years ago. and the plant Of to-day;
the latter being equipped with eontinuou,
exact @ adjustment s and control as to tenn, n
ground are shown the buildings housing
the Alca lime and hydrating plant.
In the latter part of the nineteenth
century Il was noted that certain lines
when made into mortar and placed under
water, would attain a considerable de
was investigated by several engineers anC
chemists. As a result OF this research
there was Developed natural or Roman
from the erroneous supposition that the,
were the rediseovery OF the cementinl
material used by the Romans. Thes'
came into general use early in the nine
teenth century. and were used almos
exclusively IN all important construction
in the United States until the last fifteef
or twenty years These cements. whicl
prodIlc,sd by caicination at a temperatur,
sufficient only to drive OF the carboni,
i acid gas OF rocks rich in alumina and
silica; they do nos slake on being brough
hardening under water by reaction o
their Compounds on each other. Natura
cements are. as rule, low In lime; tn
Considerable percentages Of magnesia
they vary. greatly In their composition
the variation being not only betweel
cements Produced IN different localities
same locality, and from the same quar-.
at different periods. As the natural ce
ments are produced by calcination Of tn
4 rock without previous mixing or grinding
of the argillaceous limestone, their quail
ity, as well as their chemical composition
NAV differ with each stratum of tn
not siake, Il is necessary 70. grind tn
material quite fine in order to make
available as a cement. This variabilit
IN the cements caused variation IN thei
harden slowly. taking considerable tim
to develop their strength. but ultimatel
mortars made from natural cements at
tain great hardness and toughness.
Used 144,ooo,ooo Barrels.
Over l44.oooooe barrels Of natural &C
ment were used In the United States dur
ing the period from ISIS to 1886. an
though natural cements were used {
works of such magnitude as the frs
ICroton aqueduct and the Brooklyn Bridg,
&c.. there IL no record OF failure OF I'm
portant work where these cernents wer
used
THAT of Portland. has not been satisfae
torily explained. but Il is probable ths
they harden n the same manner. A
Indicated by the foregoing. lime and NIB
, | lures OF lime with pnxxolanic materis
CON stftuted the cementitious materials Z
the ancients. and these materials wit
, natural ceDents constituted the cement
: OF our own past: that they were en-
/ nently suited for all classes OF wor
: where speed Of construction was not II
: sistent. Is evidenced by the endurance {
/ | sfrucfures- In which they were used.
I'll have not included plaster. that II. q
| | uentit.ous material made from gypsum
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