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TECHNICAL PAPER COLLECTOR’S EDITION

The late Mr. H. K. G. Bamber, one of our members, which Ciment Fondu, “Lightning” Brand and other
as a matter of fact, put forward a somewhat similar similar cements are representative. Members of
suggestion a few years before he died. A very this Institution will forgive me if I do not refer to
rough calculation shows that on every mile of road these at any length as they have quite recently
alone there would be a saving of between £5oo received a concise and very valuable report on
and £1,000 if a suitable cement could be produced such cements prepared by the Concrete Sectional
at say, 3o per cent. less than the current price of Committee and published by the Institution. The
Portland cement. three most important properties of these cements,
from the structural Engineer’s point, are very rapid
Although it is dangerous to offer any prophetic hardening, high mechanical strength and ability
suggestions it would appear that further so far as has been proved to resist the chemical
development in the manufacture of Portland action of sea water. Due to the first mentioned two
cement will inter alia tend to the production of even properties this cement is particularly valuable for
greater strength. Perhaps this will be the result of precast work in quantities where the question of
still finer grinding which in turn can only be done moulds and storage accommodation during the
at further cost unless some less expensive method maturing period is of so much moment and in
of disintegration can be discovered. The tests foundation work such as roads, etc., where from
of the fineness of cement as determined in Mr. one cause or another, it is desirable to subject the
Stamger’s laboratory by Mr. Dickson with the aid of concrete to its normal stresses within as short a
the elutriator show that there still remains a large period as possible.
proportion, somewhere in the neighbourhood of
50 per cent., of practically inert clinker or “ core “ Another equally important cement is the “Rapid
which, if still further reduced by grinding, would Hardening” Portland cement which has somewhat
add materially to the strength of the concrete. similar properties to the aluminous cements. It
is, however, considerably cheaper’, and its use
Progress in grinding is to be seen by comparing is being greatly extended in works such as road
the requirements for fineness of the 1905 making, etc., where its quick hardening properties
standard, viz., 22½ per cent., with that of 1925, viz., are manifestly of advantage.
10 percent. on a 180 X 180 mesh sieve. In actual
practice, however, the proportion is frequently as Slag cements have not as yet made very much
low as 1 per cent. It would appear, therefore, that headway, their development, however, seems to
the limit of practicability of the sieve test has been be assured, although many years have elapsed
reached and that some more precise method such since the production of this class of cement
as that just referred to may have to be adopted in was first undertaken. The British Engineering
the near future. Standards Association have recently issued a new
specification for Portland Blast furnace cement in
SECTIONAL COMMITTEE’S REPORT ON which the minimum proportion of Portland cement
CEMENTS clinker is fixed at 35 per cent. Other slag cements

Of special cements which have been introduced in which Portland cement does not enter into the
within recent years on a commercial basis, perhaps composition have made but little progress in this
the best known are the aluminous cements of country.

The Indian Concrete Journal | November 2018 13