The Minneapolis journal. [volume] (Minneapolis, Minn.) 1888-1939, 1906-03-11
ARTICLE TX.
Questions and Answers.

:. Questions and Answers.
q INCE the beginning Of these arti.
= cles, numerous inquirers have
asked for information bearing
upon this subject, and I have replied
many remain to be answered, however,
that it Is deemed best to reply thru
this medium, that the information Of
fered may have a wider circulation: If
gou are having difficulties, and they
can be cleared away thru this channel,
send In your questions.
There is quite q difference in The
price Of natural and Portland cement
in this place, the natural being sold at
price nearly 40 per cent less than
Portland. Is the natural cement adapt
ed to the making of good blocks--
e. A. L., Bowdel, s. D.
Answer.-There is quite difference
in the chemical composition of natural
and Portland cement, as we'll as dit
ference In their action when water IS
added
Natural cement Is the product result
ing from the exclamation Of an .argilla-
ceous limestone at low temperature.
sufficient only to drive off the carboniee
acid gas. Portland cement Is composed
of both argillaceous and calcareous ma
terials, intimately blended in proper
proportions and subjected to heat
which will produce fusion. But the fu-
sion point must not be reached If a
good product Is to result. and this IS
The chief reason why Portland cement
varies in quality; some of it IS under,
burned and some of 1t overturned, and
this necessitates a test In order to dis
cover the condition the calcined mate
rial was in before pulverization, as the
chemical action will vary greatly when
either Of these conditions was, present
when caleination was completed.
|, A comparison of qualities is best CIV
en- in tabulated form, thus: o..
Natural cement. specific gravity not less than
rs; Portland cement, BIO
Natural cement, fneness. residue on too sieve
10 per cent; Portland cement 8 per cent
Natural cement, residue on 200 sieve, 10 PEI
cent; Portland cement, 70 rer cent:
/ Natural cement, initial set, not less than 10
minutes: Portland cement, 30 minutes.
Natural cement, hard set, not less than 80
mirutes nor more than hours; Portland cement,
not less than 80 minutes nor more than 10
Natural cement, tensile strength, "a hours
test. briqusttes one inch square IRE IN cross sec,
i ssRs T. 80 Be'ss so6 100
f Natural cement, 1 part cement, 8 parts sand.
Z days test. days under water, same size Of
brtquetts, rs to rs pounds, Portland cement LEO
to 200 pounds - ---~-.. y ~.
|. Other comparisons might be made, as
to constancy Of volume or tendency to
Nshrinkage, but the above is sufficient
to answer@~tha. question Iintelligently.
!, An analysis will show the specific gray
ity Of Portland cement is greater than
that Of natural cement by more than
| SO per cent. -. =. ~.
That the time in which the initial
! set and hard set takes place In natural
cement precludes it's use In block
making.
That natural cement decreases In
strength materially in, seven days
under water; Portland remains con
slant under similar test.
| Which of the machines for making
blocks would you recommend for q
small plants SO many kinds are now
! on the market that it is hard to make
a .choice.-J.l g., Pierre, s.. D. .a, j,
Answer-The best machine know Of
for making concrete blocks Is a mar
who is determined that the output OF
his plant shall bear the. stamp Of ar
intelligent and conscientious 1nanufae
turer. The secret Of success lies in the
man and not in the machine he works
with, The machine controls the form
of the block; it can have nothing tt
do with making the concrete. The
writer never yet made a concrete block
for commercial use, but he has put
numerous queries to cement and sand
using basement for laboratory
dumped his mixtures into a wooder