Evening star., 1935-02-23
BUILDERS DEMAND
CEMENT VARIETIES
Nature of Work Should De-
termine Quality, U. S.
Scientist States.

There IS a marked trend in this
country away from the use of one
standard type of cement for all con-
struction projects. according to P. H.
Bates, chief, Clay and Silicate Prod
ucts Division, National Bureau of
Standards, Department of Commerce.
Consumers in particular, he pointed
out, are demanding more types and
more varieties within any one type OF
cement to meet the requirements OF
special construction projects.
Thus, there is the standard Port
land cement used in the majority of
cases, as covered by the present Fed
eral and American Society for Testing
Materials specifications; low heat of
hardening cements, such as are being
used for Boulder Dam; Portland ce-
ment to resist sea water and other
waters containing destructive salts;
and the high early strength cements
used by almost every State highway
department and many municipalities,
he stated.
The increasing use of these cements
will, according to Bates. result in bet
ter concrete. The project on which
the cement is to be used must be
carefully studied to determine whether
a saving will result from the employ
ment of a special cement which will
cost more than standard Portland ce-
ment but which may speed up con-
Struction or make possible a lighter
structure.
Bridge Experiment.
Thus, he stated, a large concrete
bridge has recently been completed
in France in which a high early
hardening cement was used because
the designer found from tests that by
so doing he could use lighter sections
than if he had employed the cheaper
but lower testing Portland cement
which resulted in the higher priced
cement yielding the lower costing
bridge.
Many of these special cements
have background of long use in
Europe, and even in the United
States they have been used off and
on for many years. but this does not
seem to be generally understood, ac-
cording to Bates.
He pointed out that it is not to be
supposed that all producers will make
all the varieties of cement which
seem likely to be in demand.
If any manufacturer can continue
to make standard Portland cement and
dispose of it at a rate and price that
will yield him adequate continued re-
turns on his investment, he should
bend his efforts to continue in that
advantageous position he said.
But, if he is assured that the con-
tinued demand for another type of ce-
ment or a different grade of Portland
cement will justify his making it, and
in so doing he can obtain a satlsfac-
tory return on the needed additional
investment to produce it. he would be
foolish not to take advantage Of the
opportunity.
Here to Stay"
Likewise it is not to be supposed
that the use of special cementS will
result in 100 per cent success in all
cases. Not even nature can make
any great masses of perfect rock. All
our deposits of building stones yield
a quota of material that can not be
GpCO lOl oIIuIIuldI puA POcCc'
1T must be remembered also that
special cements require special hand
ling. Clements having decided ad-
vantages along some lines are not so
good in other respects. For instance,
designers who are inclined to use not
only the high alumina cements but
also the very rapid hardening Portland
cements should beware of large masses
OF concrete unless they use artificial
means Of cooling.
The various types of hydraulic
cements are here and here to stay,
and there is no use kicking Accept
the new cements as gracefully as
possible, make them if money is to be
made in producing them, but if not,
don't assume any obstructive attitude.
Remember the world moves on and
you either keep pace or are lost"