Page
THE EXPRESS LIFT CO., LTD.
'WITH WHICH IS INCORPORATED THE BUSINESS OF
SMITH, MAJOR & STEVENS, LTD.,
EXPRESS SMS
LIFTS
MODERN,
LIFTS
FOR
MODERN BUILDINGS
SPEEDY RELIABLE SERVICE
HONG KONG DAILY PRESS, MONDAY, DECEMBER 28, 1931.
ENGINEERING AND
BUILDING
CEMENT AND CEMENT MANUFACTURE
MODERN CONCRETE CONSTRUCTION.
IMPROVEMENT OF MIXING MACHINES.
That modern constructional work is the result of a revolution effected by the large application of concrete, which in turn is the product of the application of Portland cement, is
other band, the great advantage of immunity from the attack of frost, admitting of the laying of the material under conditions of cald not survived by the ordinary types of concrete,
This type of cement, thus meets the needs of work of extreme to the concrete. Further, there are urgency and, moreover, become nuushor of chemical conditions, not available under conditions not satis iufrequent in constructional work|factorily withstood by the usual which affect the slow but neverthe-forms of concretę.
A
of 1) to full-lond
Those The Nasd for Bicient. Mixing, drives are frequently afzierge in Whatever care may bave been ex- dividual capacity and of a steady eraised in the choich both of the and continuous Bature
quality and quantity of the Do- Now as the ordinary induction poneuta of concrete, a vital factor robor" operates, at a power factor in your contrato production is that less than wilty, thora, is an un of mixing, which must be consistant- avoidable loss of power all the way ly intimate so that the surfaces of from the station to the motor. A both coarse and Ans aggregaben: ere saving could be effected by the in- ocvered with the gemene water mix- crense of the load factor to unity, ture. While this mixing can be some inducement towards which done by hand, it is unfu-to-any-that- takes the form of a substantial tarifa good modern mir will give rebate by the supply compaay, togs-much better results, wiër a saving thor with the ralist on the works of material and labour and with foedera, transformers, &c., by the the sons of any variation in the reduction in wantless or idle"product.
current.
Mixing machines of the open This desirable "increase in the drum type provide a well-known load factor of the coment, plant load sight where conorate work is under can be ensured by the uso of auto construction. On large contracts synchronous motors for the larger those machines may be fitted with--- constant speed drives. Available number of attachments to speed “machines of this type start "and" up" the operations of measuring synchronise automatically against charging and placing the mixture. full load and are amenable to easy. Thus a now batch of material may be charged into a hopper while the operation.
Reinforced Construction, previous batch is being mixed, wisa In the reduction of the relative the appreciable saving of time and high cost of building by the older increase in the capacity of the unit. methods of construction, the apIn the extending use of comerate |plication of reinforced sonerets his such efficient types of machino, in- played a large part, securing the timately mixing carefully chosen advantages of adaptability, fro re- | materials in accurately measured to almost every type of construc sistance, durability, and suitability quantities, will play a large part
Preservation of donorate, tion, in addition to the advantage Finally, the finish of the concrete of reduced coat. The advantages surface in constructional work has the structure, Such finishing conts. of the dual product from the me- much to do with the permanence of fact that both steel and concrete should be damp proof, fire resist offer resistance to special types of ing, washable, quick drying, un stresses, and by their judicious use affected by soids or alkalis and al it is possible to develop maximum mospheric conditions, elastic, pre- resistance to loads with the other sazvative, and highly luminous. advantages already referred to Of These are requirements which can special importance in the fact that readily be met in materials, now the stresses and bending moments available, stone ccverings being occurring incontinuous beams over used for exteriors and special types Manufacturing Problems," 4 number of piers are less than of paints for "interiors, For the numerous operations in those in the number of individual cement manufacture involving pow beams on the same number of piers, or the advantages of the electric! This admits of the erection of drive are outstanding, but the ap-structures in reinforced concrete plication of electric power presente which could not be built by any a number of problems necessitating other mathhod. There is thus secur a thorough knowledge of the manu-ed the minimum number of sup facturing processes involved and ports & valuable feature where such also of the operating conditions." restrictions on floor space must be
Inasmuch as the manufacture of reduced to a minimum. cement is a continuous process, all stages are interdependent. avoid the risk of breakdown of con-
Prominent: among the features in which there is admittedly some room for enhanced propartics is the time required for the development of its maximum strength." This is à simple statement feeding no fur-from four to twenty-eight days, and ther jurtification, Since the obar-loading before the end of this period vation by Parker in 1796 of the set must result in permanent damage ting properties of this type of cement, and the considerable addi- tion to our knowledge of the materi- al, which was the result of the work of Aspår in 1821, who emphasised less certain decay of the aét materi- Wheile alumincus cement is a re-chanical point of view he in the not only the composition but alsoal, These chemical conditions inlatively costly material it is invalu- we degree of fineness to which the clude contact with sulphates and ahlo in its production of a truly per- material should, for sffective use, be dilute acids, which make their mark
on conereto by its progressive demanent concrets outside the limitn reduced. the application of Porteny. Again, it has long been re- tions of Portland cement, and by
and cement has proceeded apaca.
cognised that sea water definitely the judicious use of the right cement attacks ordinary
for each well-defined set of cond From time to time new applica wounded with Portland cement, and tions concrete becomes a truly ubi tions for this material are being in an extraordinary volume of research, quitous material. troduced. added to which is the work has been carried out in all order to factor that, at the result of con. civilised countries in aiderable seiontife research, it has life of the concrete.
minimise the decay and prolong the Yet again been possible to so exactly define considerable care needs to be exer the correct conditions for the suc
cised in the laying of concrete dur essful application of the materialing sold weather, the only safe in the production of sound concrete methode being that of protection of that may praction! man with a clear; the newly laid material from the knowledge of the factors involved disintegrating effects of frost. cat achieve good results with the exercise of reasonable care in the choice of the materials, their moa- stevement, and method of mixing."
卞
concrete
corn-i
Aluminous Cementa. Fortunately, these defects and the limitations which they imposs upon the extended use of Portland cement
ין
J
To
These stone paints offer the fur- ther advantage that they are ob- 'tainable in almost every shado of colour, and thus lend themselves to decorative effect in addition to their preservative properties. Combined with quick surface drying, there is a slow process of hardening which resulte in a covering absolutely re sistant to moisture penetration.
FOR DETAILS APPLY TO
THE G.E.C,, QUEEN'S BUILDING, CHATER ROAD
d
EVERYTHING (9.E.C.) ELECTRICAL
Use Green Island Cement
for
Constructural Work of
Every Description.
HOW GREEN ISLAND CEMENT IS MADE
BERVAR
THE SEA-WATER-PROOF
SPEEDBOAT VARNISH
W. R. LOXLEY & CO.
·Copyrizbi
Action
Edune, Lenbocs
Members of 54 C.M.A.
YORK BUILDING,
CHATER BOAD.
a
Berger Product
PROPOSED ARRANGEMENT OF NEW GREEN ISLAND CEMENT CO, WORKS.
Limiting Factors.
concrete are not insuperable dif- tinuous operation every motor enlties, and by the use of aluminous ceinents, these troubles are entirely overcome
in
In spite, however," of all its ad-
use must be capable of operating vantages, and the precision of speci-
at full load not only for a 168-hour fention to which it can be produced,
week, but even months or years, a has had to he recognised that
These materials differ widely from with but little skilled attention. As, there are some limitations to its use. From time to time failures which Portland cement both in composi-too, cement works duty involves) have occurred have invariably been tion and method of manufacture. heavy overleads, robustness must due to the lack of appreciation of
contrast with Portland constitute a first essential of the these limitations. While Portland As one cement is a stable product which is cement, the composition of the electrical equipment. relatively cheap, and which pro- aluminous type shows the presence duces a concrete of absolute per- nanence under the vast majority of of nearly 80 per cent of the two cnditions, is fails to offer sufficient materiale, alumina and lime. This resistance to a number of conditions -large proportion of these two which are common to some forms of materials brings with it properties efficiency can also be ensured, and constructional work.
which can only be regarded as quite oven a small increase in efficiency unique. In the first place, a materi. may result in a considerable econo my in view of the fact that the al of this type will attain a strength operating units are running over o in one day which may be far in 'large proportion of their life. advance of that developed by Port Motors of the alternating current
Electric Motors.
COMPLETE ELECTRICAL INSTALLATIONS
reith
C. M. A. CABLE.
Advice and Estimates given free on all types of
<
LIGHTING & POWER INSTALLATION
by an experienced.
ELECTRICAL ENGINEER
retained at our Hong Kong Branch".
The General Electric Co. (of China), Ltd.
QUEEN'S BUILDINGS.
BONG HONG.
Fortunately, simplicity and robustness are obtainable so that the minimum maintenance and replace. mente can be effected by the average handyman. Combined with these characteristics, that of electrical.
land cement concrete in twenty- eight days. While, moreover, this type are most commonly in use as the result of the standard supply dogien of strength is so rapidly at of this country. Only seldom are tained, there is the further increase direct current motors called for. in strength over long periods, ao
The squirrel cage AC motor, which is the type most commonly used, in that it is difficult to ascertain any one of the simplest and most robust lunit to strength development machines made. Combined with the This very important discovery advantage of having no wearing was made in 1909, but it took some parts other than the bearings, these ten years of research to develop a motors offer high efficiency at low product which could be produced cost per b.h.p. They can thus bë with that degree of reliability which i used for numerous auxiliary drives justified its being placed before the ant, with attention to such design publio Whale
as ensures high starting torques, Cimont Fondu” was a French discovery, it is in. they may be employed for a very:
large proportion of drives... teresting to note that the material was introduced into this country in frame sizes is thus desirable and A measure of standardisation pl 1923 and that it is now a Briti possible for such smaller drives as product, having been manufactured those of elevators, conveyors, slurry just outside London for the past. six years.
pumps, mixers, water pumps and fans, but for the larger drives which cover the washing plant, rough finishing and tube mills. The rapid development of con- clinker grinding plant and the coal- siderably strength combined with mills, the same degree of standardi- resistance to the chemical attack of ; sation is possible. Advantage, too, frequently occurring conditionea ara, Í nccrues to the use of a type which however, not the only advantages involves an inner casing completely ngeruing to this type of material, enclosing windings, &c., and an Gront as these advantages are, they cuter casing which provides an air are further reinforced by the fact duct so that air driven by a fan that during hardening appreciable between the two casings ensures next is generated. While on the one adequate cooling.. hand this may pocnaion some slight evaporation of the water used in For the larger drives a slip-ring
Useful Characteristica.
Auto-Synchronous Kotors, M
4.
Green Island Cement is manufactured from hard limestone, and clay. It is necessary that, these materials should be finely ground in order that they may come into intimate contact with one another in the burning process.
The finely pulverised materials are mixed. in a certain definite proportion, roughly one part of clay to three of limestone, and are fed to the Rotary Kilns.
1.'
In these kilns they meet the hot gases and flames generated by pulverised coal blown in at the other end of the kilos, and after various " chemical actions have taken place, they combine
to form Portland Cement Clinker.
17
The Clinker is ground down with a small percentage of gypsum to regulate the setting time, and Green Island Portland Cement is thus produced.
Although sounding so simple, in reality the process is an intricate combination of mechanical, physical and chemical operations, needing great skill and care. Nothing but constant and accurate supervision will yield the results 80 well-known with Green Island Cement, namely, strength, uniformity and reliability.
USE GREEN ISLAND
Issued by the
CEMENT
GREEN ISLAND CEMENT CO., LTD.
2ND FLOOR,
EXCHANGE BUILDING.
the mixad concrete, this boing readily catered for, there is, on the
motor is necessary, since the start- ing torque required in of the order