No_6_1956 — Page 77

BOOK REVIEW - PAVIOR SCREEDS

The School of Architecture, University sections, Functions of Screeds: General current practice. Here again the user is of Hong Kong, has in preparation Considerations; Preparation of Surfaces; at liberty to adopt whichever he prefers, "Occasional Papers" to appear three or Mixes; Laying; Thickness; Hardening but it should be borne in mind that local four times a year, under the general title Screeds; Waterpoofing Screeds; Chemical practice may not be the best although in of Materials and Techniques in Building Resistant Screeds; Grinding and Polishing; itself adequate. The argument that new Practice, directly related to current build- Non-slip Screeds; Screeds for other Floor methods or practices are not understood ing usage. They are intended for the Finishes; Decorative Screeds; Screeds to by local craftsmen and therefore would average architect and student who has Falls; Lightweight Screeds; Floating be badly executed and possibly more not time for a complete study of the im- Screeds; and Defects. Three tables of costly admits of there being no merit in mense amount of technical information Grading of Sand, Grading for Aggregates, progress. Many of the new processes constantly flowing from research stations and Heat-insulating Properties, and notes take into account the lack of skill or and research organizations.

on Pigments and Non-proprietary Harden- knowledge in the operative using them ing Treatments are also included.

but success can be achieved by under-

good supervision of the work. standing of the operation in hand and

Each paper will appear under a general trade heading and will deal with a parti- cular aspect of the work of that trade. The first under the general heading of Pavior, deals with Screeds. It will be followed by Concretor: Concreting 172 Building Work. Others in course of pre- paration are Painter

Decorator: Materials and Techniques and Asphalter: Asphalt Roofing and Tanking, etc.

and

W. G. Gregory, B. Arch., A.R.I.B.A., Senior Lecturer in Building Construction at the University of Hong Kong, with a wide experience on building in the Tropics and the United Kingdom, is well qualified in the task he has set himself in the pre- paration of these papers.

Mr. Gregory, in his Introduction, says: "The average architect and the student have not the time for a complete study of all

the developments which come to their notice and it is intended that these notes will provide them with the basic information on developments and current practice.

"Conflicting recommendations are often encountered in building trade literature; these will be critically analysed and users will be left to choose the material and technique they prefer.

"References to further sources of in- formation will be given, for those who wish to pursue the subject further.

"It is proposed to publish these notes periodically and they will cover as wide a field as possible. They will come out in pamphlet form, so that they may be filed in any existing system or in folders which will be available from the publisher. that the pamphlets are It is suggested filed under trade headings conforming to those in the Standard Method of Measure- ment; each pamphlet will be marked with the appropriate trade heading, subject and reference number for indexing.

"Comments from personal experience on the behavior of materials and on the success or not of techniques will be we come and this information will be publish- ed with due acknowledgment,

"The extent of the contents of pani- if the contributor so desires, in subsequent notes, phets will depend on the complexity of revised issues or as addenda.

the subject being dealt with and will be priced accordingly.''

We have received a copy of PAVIOR— SCREEDS. and we feel sure that, from the scope of the work and the thorough ness with which the subject has been treated, it will prove an invaluable source of information to architects preparing "The particular conditions and circum- their specifications, to contractors who stances of the requirements of Hong Kong wish their work to be up to the highest and tropical countries will be taken into standards, and to everyone connected with account or referred to. the building industry.

These booklets are being published by The the Hong Kong University Press. first four books mentioned above are to be priced at HK$2.50 per copy but, as has "It will be found that certain recom- already been mentioned, the price of The paper is divided into seventeen mendations will not conform to local further pamphlets may vary.

Limited

in

TUBES MADE FROM "ALKATHENE"

The outstanding advantages of tube made from "Alkathene" are:

1. Lightness

Prior to and during the Second World manufacturers of polythene tube in all War the high molecular weight polymers parts of the world using "Alkathene of ethylene discovered by the research supplied by the Plastics Division of I.C.I. chemists of Imperial Chemical Industries 1933 were used aimost ex- clusively for their outstanding electrical insulating properties. After the war, however, many new uses for "Alkathens" (the L.C.I. registered trade name for ethy- lene polymers) were developed and one of the most important of these was the anufacture of tube for cold water plumb- ing, household sanitation and chemical plant.

water

At the outset Imperial Chemical Indus- tries Limited was alone in recognising the potentialities and advantages of tube made from "Alkathene" and between 1946 and 1952 sold and assisted in the installation of many thousands of miles of tubing for domestic systems and agricultural supplies. During this period a committee was set up by the British Standards In- stitute to formulate standards for tube made from polythene and eventually two specifications were published, B.S. 1972 and B.S. 1973. Today there are many

Polythene tube is 1/8 the weight of the equivalent size of steel tube and 1/11 the weight of lead tube. 2. Corrosion resistance,

Polythene tube is not affected by water and is resistant to acids and alkalies. It does not, therefore, de- teriorate when it is buried in corrosive soils.

3. Resistance to low temperatures

4. Non-toxicity

"Alkathene tube is non-toxic and non-contaminating.

5. Flexibility

Tube made from 'Alkathene" is flexible and it can be stored and car- ried as a coil in fact, some manu- facturers make coils up to 500 ft. in length.

6. Installation

-

Because Alkathene" tube is flexible

a

it is easy to install. It can be laid permanently underground by using mole plough and as it will not discolour or mark the turf, pierced tubes can be used to irrigate plants under glass, sports grounds and parks.

"Alkathene" is a good thermal in- sulant and tubes made from it help to prevent water freezing because cold is conducted less easily through "Alka- thene" than through metal. If, how- ever, a water pipe line made from tests is a pressure test. "Alkathene" does freeze up, the tube is wall thickness and size, the tube must be sufficiently strong and elastic to with- tested at pressures between 1.900 lb./sq. stand the expansion of water into ice in. and 1,120 lb./sq.in. The Polythene without bursting

most widely used for the manufacture of

The British specifications drawn up to formulate standards for polythene tube include tests which tube made from

must "Alkathene"

One of these pass.

Depending on

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