Issue 7

SINCE the year 1920 the Compagnie de la Fonte électrique, at Bex, has been manufacturing an aluminous cement, which it has placed on the market under the name of Electro-Cement. This article, produced in accordance with the formulae of the French chemist Bied, has been subjected in Switzerland to various interesting uses, advantage being taken of its rapid and high mechanical resistance, with two or three days’ hardening, and its chemical unalterability in the presence of selenitic waters. Professor A. Paris

THIS subject is of particular importance in these times of shortage of bricks and skilled labour, since concrete block building provides a simple means of obtaining a really satisfactory substitute for the older methods, and offers a solution to the present difficulties. Major W.H. Smith

NUMEROUS systems of concrete block construction have been invented during the last 20 years, some of the earlier ones being, unfortunately, radically unsound, and, as a consequence, thousands of concrete houses have been erected in this country and on the Continent which are unfit for habitation, and the word " concrete " in connection with dwelling houses has got such a bad name that it will take a long lime to overcome the existing prejudice. But now that the subject is understood, and the reasons for the faults of the earlier systems are recognised, it is possible, and, indeed, easy, to make concrete houses every bit as dry and warm as the best brick houses, and there is no excuse for a concrete house being in the least degree damp or cold. The usual trouble was that condensation took place on the inner surface of the walls, due to the difference of temperature inside and outside the house, and due to the inner skin of the walls being made of ordinary concrete, and not of a more or less non-conducting material, such as " breeze " concrete. Colonel H. Vaughan Kent

STUDENTS’ BUREAU. The following simple problem in Graphic Statics is supplied by The Bennett College, Sheffield, the Governor of which will give a prize of 10s. for the best solution. In allowing points, neatness will receive the same consideration as accuracy.

The last ordinary general meeting of the Institution of Structural Engineers, for the 1923-24 session, was held at Denison House, Vauxhall Bridge Road, London, S.W.1, on Thursday, May 22, 1924. The President (Major James Petrie, O.B.E., M.Inst.T., etc.), occupied the Chair, and a paper on “Economics in Concrete,” by Mr. B. Price Davies, F.S.I., M.S.A., M.R.San;I.,A.M.T.P.L., A.I.Struct.E., was read, and the following discussion ensued.

IT is not surprising that although the House Of Commons has passed the financial resolutions relating to the Government's housing proposals, the scheme for providing two and a half million houses in 15 years has met with a great deal of criticism. On purely financial grounds the proposals appear to be providing the community with far too expensive a luxury, for the subsidy of £9 per annum from the Government, and £4 10s. from local authorities for each house, spread over a period of forty years, will cost the nation a total of nearly £1,400,000,000. Economically, however, the scheme is quite indefensible, and when Mr. Wheatley, the Minister of Health, proudly described it as "suspending the laws of supply and demand," he touched upon what is in reality its weakest point. The whole principle of giving subsidies is thoroughly unsound, and has been condemned time and again by international and other economic conferences in outlining the steps which should be taken for post-war reconstruction. The Brussels Financial Conference, for instance, recommended that the artificial cheapening of food, coal and other materials, and the maintenance of postal rates, railway fares and other Government services on an unremunerative basis should be abandoned at the earliest opportunity. House building, of course, was not specially mentioned, but the same arguments and considerations apply equally to the building trade. This country has in most cases been far in advance of any of the Continental nations in avoiding the economic traps which are inherent in the subsidising of trade in any form, but housing is an exception to this general rule. During the European War housing accommodation fell below the normal requirements of the nation, and fresh building was restricted, owing to the depletion of the numbers of men engaged in the building trade. By the continuation of the Rents Restriction Acts the necessary stimulus to fresh building enterprise was withheld, and if effect is given to the present proposals for subsiding house building over a period of 40 years, the uneconomic situation is likely to be perpetuated. Arrangements have, of course, been made by which apprenticeship in the building industry is to be increased, and the scheme is to lapse if prices are unreasonable, or if two-thirds of the houses provided for are not built. The scheme, however, presumes that the building industry will attain a considerably larger output than before the war, although the number of workers has actually decreased since 1914. Output per man is also rather lower, and in these circumstances there seems to be no guarantee that the houses provided for will be forthcoming. It is evident, therefore, that the scheme, in spite of the subsidy, cannot succeed unless very great changes in labour methods are made, while even if the Labour position were satisfactory it may be doubted if the supply of building materials generallv could be made adequate to requirements. The many unfavourable

IN 1921, on the occasion of crushing tests being carried out with hooped columns made in concrete composed of aluminous cement mmufactured at Bex (Electro-cement), Professor A. Paris, Engineer, drew our attention to the considerable heating disclosed on lifting out of the mould. J. Bertet

Metallic coating of building materials may be grouped under five heads : (1)Electrical deposition of spelter and nickelling, chiefly on iron sheets and on small structural members and accessories; (2) plating with thin sheets; (3) gilding or silvering; (4) painting with certain kinds of metals reduced to powder and held in suspension in a fatty or spirituous medium, as in aluminium painting, and the whole range of processes known as “ bronzing. ” A development of this last is (5) the spraying of metal powders or vapours.

M R. SINGLETON-GREEN’S plea of contentiousness does not warrant generalisation from insufficient data nor the support of a practice which has proved inefficient under certain conditions, and is contrary to a number of ascertained scientific facts. Harry Weston

THE following remarks apply to the use of Portland Cement only, and are based on the author's own experience :- The time seems to be past when engineers seriously objected to the use of reinforced concrete in sea-water, although its application has not always been successful, but when this has been the case, serious faults in design or execution account for such results. Herluf Forchhammer

AT the present time there are so many varieties of roof coverings on the market from which to choose, that it has become a problem for the discerning architect or engineer to decide definitely upon which class of roof covering to specify for the building he may have under consideration. This is a much more important item in building construction than seems to be generally recognised, and one to be decided early, as the type of covering to be used has an influence, not only on the roof design, but on the whole supporting structure. A new roofing, however efficient and economical in actual use it may be, does not always appeal immediately to the conservative architect or engineer. He probably has had experiences, or is profiting by the experiences of others who have been carried away by the verbosity of the salesman to his ultimate disillusionment. The architect and engineer must be satisfied that the material he proposes to employ on his roof is the most efficient and economical he can procure, that it will be suitable for his purpose, and that, when in use, it will be a lasting credit to himself and satisfactory to his client.

In recent years structural steelwork and reinforced concrete have progressed upon somewhat parallel lines, and comparatively little has been done in combining the two methods of construction. This is probably due to the fact that the two methods of construction have been regarded as competitors, and the specialists in each of the methods have concentrated upon demonstrating the advantages of the one compared with those of the other. Ewart S. Andrews