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the future. March, 1919 a heavy sea. In time considerable improvements may be made in design. At least this is a worthy problem for ship architects to work upon. The field of research is new. Experiments in developing a better concrete for shipbuilding have been conducted with collision, stranding and fire hazards in mind. To make a practical ship of this material it is necessary to satisfy the marine under- writers on all these points and the concrete people have approached their problem with this in mind. The new concrete, consisting of a shale which burns at about 2400 degrees and cement burning at approximately 2600 degrees, gives a homogeneous mass which shows upon test no deteriora- tion when burned to 2000 degrees Fahr. Here is the first advantage shown over steel ships, because it has been demonstrated that steel plates will buckle at 700 degrees. The heat test proves the great advantage the special concrete has over the stand- ard concrete. For instance gravel, containing from 9 to 20 different kinds of rock per cubic foot with the resultant variation in expansion and contraction, would not stand near the degree of heat which the special concrete will. Results of Experiments It was of this new kind of concrete that the ATLANtus was built and this is the kind which, from present in- dications, will be used in all the bet- ter grades of concrete shipbuilding in The manner of the dis- covery of this grade of material is interesting in itself. An American cement expert was in Germany some time before the war when it was dis- covered that the Germans were using clinker in concrete because of its lighter aggregate. When the concrete shipbuilding program was started in the United States during the war this discovery was brought to mind and immediately some experiments at the bureau of standards in Washington were started. From 10 to 12 per cent of carbon coal was included in the mass and made into briquets. These were put through a kiln at 2400 degrees for 80. minutes and expanded to about 10 times the original size. The treatment left in the product mil- lions of hermetically sealed voids. This product in a 1 to 3 mixture tested for compression gave an aver- age of 4750 pounds: per square inch in 7 days, and over 9000 pounds in 28 days, and weighed on an average 105 pounds per cubic foot. A den- sity test showed less than 2.5 per cent moisture. The shipbuilding concrete is made from a cement which is produced in THE MARINE REVIEW a special, although not highly in- volved, manner. The material is sub- jected to raw _ grinding, using the proper chemical analysis and even temperature of heat in calcining. The clinker is aged for not less than 30 days and then ground to a fineness of 95 per cent through 200-mesh on the finish, Cement producers have become familiar with this special material in a surprisingly short time. Some American producers are today Record Voyage for Troop Ship HEN the Canadian Pacific liner, recent- ly slowed down her engines to enter Vancouver harbor she completed a Empress oF ASIA, remarkable ocean voyage. Carrying 1500 soldiers of the Canadian ex- peditionary forces bound for their homes in British Columbia and Alberta, she steamed all the way from Liverpool, a distance of 8586 nautical miles. The route taken was by way of the Panama canal. This is, without a doubt, the long- est voyage taken by any troops par- ticipating in the world war. The first lap of the journey to the Pana- ma canal is approximately 4530 miles, while the distance from the canal to Vancouver is about 4056 miles. The huge liner was turned over for service as a transport shortly after the war broke out. She was returned to commercial service be- “tween Vancouver and the Orient after debarking her contingent of troops. shipping it to Japan for shipbuilding and a promising French inquiry has been received. The American pro- ducers have become highly expert in the burning of the cement, having sur- passed all foreign producers in this. Developing . Light Aggregates But the American cement producers are not entirely satisfied with the phenomenal advance already made. They are today developing still fur- ther the light aggregate, using fullers’ earth which weighs 25 pounds per cubic foot. This, mixed with blue clay or shale, running reasonably high in aluminum and iron oxides and about 10 per cent of carbonate of coal, is finely ground. It is anti- cipated that, when the experiments are completed, this aggregate will equal if not exceed in strength the present improved concrete, and will weigh about 80 pounds per cubic 125 foot. It is hoped by these experi- ments to develop a commercial con- crete of one-half the weight of stand- ard concrete, and of equal if not greater strength. The strength of the material having been established, it would seem that the lighter aggregate has advanced the art of concrete shipbuilding by many years. Tests of elasticity have shown that concrete exceeds steel. A test panel of reinforced concrete, 7 inches thick and 20 feet square, was deflected 8 inches. When the load was removed the panel came back to within -inch of its original position. Taking all elements into consideration, it has been reckoned that 2-inch reinforced concrete matches a '%-inch steel plate. The Faitn has walls 4 inches thick, and the ATLANTUS has walls approximately 5 inches thick. That should be equal to l-inch steel plates in the case of the first and 1%4-inch steel plates in the case of the second, had those vessels -been built of steel. Tests Antifouling Coating Building seagoing vessels of con- crete has also prompted many experi- ments in other materials incident to shipping. For instance, an antifouling coating is being used on the outside of the concrete ship up as far as the water line. Many kinds of materials have been proposed for this work and one preparation is of a cement nature which gives a true bond on the con- crete, using about 10 per cent of copper. This corrects the porosity of the concrete should any particular mixture be deficient in that regard and also renders it acid proof. It is said to be impossible for barnacles to attach themselves to the side of a concrete vessel coated with this mix- ture for any great length of time, the granular nature of the coating failing to give barnacles a hold such as is afforded by the fatty mixture of ordinary paint. The builders insist that it is not necessary to paint a concrete ship except for the sake of appearance. Sensitive instruments were attached to the Fairu that all strains and stresses — might be studied. These instruments in- dicated but little vibration, which, it is insisted, proves the value of having a true monolithic type of construction with perfect bond. Such a ship does not rely solely on the concrete for its strength, but all the strains are figured. out to be resisted by con- crete and steel. All rods are electric- ally welded together so that each strand is continuous. The ribs, or frame, are designed in the same man- ner as for steel ships and outside of them is a network of welded rein-