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The Structural Engineer

Two Structural Failures Sir,-Recently two structural failures occurred, which have been considered of sufficient public interest to be described in the Literary Digest, a periodical that collates Press opinion and gives excerpts of matters of unusual interest. One of these was the Gleno dam failure in Italy. The other was the total collapse of a 200-room hotel building, seven stories of which had been constructed. The latter structure was a reinforced concrete building in Benton Harbour, Michigan, U.S.A.

The Structural Engineer

UNDER this title, an endeavour will be made to give the ultimate results of practical experiments with concrete mixtures whiah have been carried out intermittently over a period of four years. The author has made his investigations as opportunities lent themselves, and found himself, after his first series of experiments, obliged to tear up the results of much labour, and persist later in a more thorough manner. This has happened several times, and this paper will be practically confined to the results of 1923, and as such, will be referred to here. B. Price Davies

The Structural Engineer

AS is the case with all furnaces a rotary kiln requires a certain amount of air for combustion of the fuel, enough air being admitted to the furnace to afford complete combustion, otherwise we get in the flue gases unburnt carbon which is wasted. Francis Lindstead

The Structural Engineer

ALTHOUGH Portland cement was first, produced in England in 1824, the product of that date can hardly be considered as belonging to even the same class of material which to-day bears the name. The present era of Portland cement came into being with the development of the rotary kiln, and its beginning may be considered as contemporaneous with the opening of the twentieth century. The product of today is materially superior to that of twenty years ago, largely because it is manufactured under more definite supervision. The mechanical rocesses involved in its making have been highly developed and the regulation of the raw material at all stages, from the quarry to the finished cement, has, with the single exception of the control of tlhe kiln temperatures, been brought to a high state of perfection. Notwithstanding these great improvements and developments, there has, however, been no substantial change in the inherent characteristics of the cement itself. The product, of to-day is more uniform in quality, is ground more finely, and develops somewhat greater strength, but its essential properties have, with the passing of the years, remained unchanged. No new cements have been announced until quite recently, as in the case of those based on a high alumina content. Thaddeus Merriman

The Structural Engineer

Increasing attention is being given, by engineers to this branch of civil engineering, principally in connection with the manufacture of the necessary steel reinforcement and in the selection, grading and mixture of the requisite concrete aggregates. That the latter question is of the utmost importance there can be no doubt; in fact, many of the successful reinforced concrete roads, for which the manufacturers of various fabrics are taking no little credit upon themselves, are in reality due to the quality of the concrete rather than to the amount and arrangement of any embedded mesh. H. Weston

The Structural Engineer

The treatment of concrete surfaces with siicate of soda is by no means a new process. Until quite recently it has been confined to the treatment of factory floors to prevent dusting, and the best results have not been contained consistently because the grade of silicate of soda used has been unsuitable and the methods of application have not been properly studied. L.A. Munro

The Structural Engineer

THE cost of grinding the raw materials, coal and finished cement is a considerable proportion of the total cost of cement manufacture. With a view to reducing this cost of grinding, the British Portland Cement Research Association has carried out a comprehensive research dealing with some of the fundamental principles governing the crushing of materials used in cement manufacture to a greater degree of fineness. Chas E. Blyth, Geoffrey Martin and Harold Tongue

The Structural Engineer

THIS3 question of density when relating to concrete for all purposes, and particularly when the concrete is to withstand a hydrostatic pressure, is all important to the engineer, and hence it is no wonder that he is tempted to administer “patent medicines” to the concrete when he has doubts as regards its “bodily fitness.” Alfred S. Grunspan