Historical Sketch

It was not until 1896 that the annual do mestic production passed the million barrel mark.

The general commercial application of Port land cement concrete to construction work may be said to date from 1895. It had previously at tained wide use in foundations, and at this time its development was beginning for such struc tures as dams, piers, breakwaters, sewers, and subways.

Several causes may be assigned for the com paratively slow early growth of the industry, followed by its later marvelous activity. In the first place, the American product, in the early days of the industry, was inferior to the im ported German and other European makes. The latter were long looked upon as standard; and it was only after slow and tedious experimenta tion that the present improved American meth ods of manufacture were developed so as to pro duce a high-grade cement which, under the tests necessary for all structural materials, could be depended upon to give uniform and thoroughly reliable results. Moreover, the natural cement industry had attained a flourishing growth, and its competition had to be overcome. Again, the cost of imported Portland cement, on account of the tariff, continued high; and it was only with the gradual improvement in the processes of manufacture that the price asked for a domes tic product of a grade equal to if not better than the foreign fell to a figure at which plain con crete could compete with stone masonry, or re inforced concrete with other constructive ma terials.

As a result, however, of this gradual im provement in quality and lowering in cost, do mestic Portland cement has now almost entirely displaced the imported European product in American markets. Striking evidence of this is found in the Portland cement exhibits which were made at the Columbian Exposition in Chi cago in 1893, and at the Louisiana Purchase Ex position in St. Louis, Mo., in 1904. At the Chi cago World's Fair of 1893, a very noticeable fea ture was the absence of any American Portland cement exhibit, while Germany had elaborate exhibits of this material. At St. Louis in 1904, these conditions were exactly reversed; and the conspicuous absence of foreign cement exhibits worthy of note served to emphasize the with drawal of foreign cements from the American market. In 1893, more than four-fifths of all the Portland cement used in the United States was of foreign manufacture. Within the following

decade the importations fell off about three fourths. From one of the smallest, the United States has taken foremost rank among the larg est Portland cement producing countries in the world. And records compiled from tests made by government and private engineers warrant the claim that the leading American brands of Portland cement are superior in quality to any of the foreign cements manufactured at the present day, this superiority being due to unsur passed raw materials and the high grade of technical knowledge and skill embodied in American machinery and processes of manufac ture.

In addition to improvement in quality and lowering of cost, a most important factor that contributed to the rapid expansion of the Port land cement industry in the United States was the application of concrete to steel structural work in fireproof building, and the subsequent development and widespread adoption of what is known as the Reinforced Concrete type of construction. These quickly created an unprece dented demand for good Portland cement.

Reinforced concrete is simply concrete in which steel has been imbedded to give additional strength and elasticity. Plain concrete has great compressive strength, and, when used in the form of pillars and posts, is capable of carrying heavy direct loads. It is weak, however, under tension—that is, when subjected to direct pull— and the principle underlying reinforced con struction is simply that of incorporating steel members in a mass of concrete in such a manner as to enable the mass to withstand the tensile of transverse loads.

The general use of concrete on steel struc tures, about 1895, opened up a wide field of new opportunities for the use of cement. This field was enormously expanded by the general ac ceptance, about 1900, of reinforced concrete as a type of construction of practically unlimited possibilities. The subsequent history of the Portland cement industry in the United States has, in fact, coincided with that of reinforced concrete, one being but a reflex of the other in its unexampled growth. A detailed historical sketch of the development of reinforced con crete systems will be given later, under the head, of "Reinforced Concrete." The subject is here referred to only in its bearings on the develop ment of the Portland cement manufacturing in dustry.