PREFACE.

By JOSEPH A. HOLMES.

The authority for the investigations described in this report is embraced in the following item of the bill making appropriations for the sundry civil expenses of the Government for the fiscal years 1906 and 1907, as follows:

For the continuation of the investigation of structural materials belonging to or for the use of the United States, such as stone, clays, cement, and so forth, under the supervision of the Director of the United States Geological Survey, to be immediately available, one hundred thousand dollars.

As illustrating the magnitude of the work which may be affected by these investigations, it may be stated that the expenditures of the Federal Government for building and construction work now approximate $30,000,000 per annum, while the expenditures of the country at large for similar purposes are in excess of $1,000,000,000 per annum.

It was with a view to reducing the cost and improving the quality of the materials used in this building and construction work that Congress was asked to provide for the investigations of structural materials now under way. In order that this work might be done in such a manner as to best meet the needs of the Government in this respect, an advisory board was organized, on which were placed by the President the chiefs of each of the Government bureaus having in charge important building and construction work, viz, the Chief Engineer of the Isthmian Canal; the Chief Engineer of the Reclamation Service; the Supervising Architect of the Treasury Department; the Chief of the Bureau of Ordnance of the Army; the Chief of the Bureau of Steam Engineering of the Navy; and representatives of the Corps of Engineers of the Army and of the Bureau of Yards and Docks of the Navy; and in order that these investigations thus conducted for the use of the Government might be satisfactory to the engineers of the country, and also of service in meeting the needs of the general public wherein they agree with the needs of the Government, representatives of the national engineering and allied organizations were similarly brought into consultation

VII

as members of this advisory board. The members of this board connected with the Government service were asked to submit recommendations as to the investigations which were specially needed in connection with the construction work under their supervision; and the plans covering each investigation were submitted to and approved by the members of this board before the work was undertaken.

Engineers and architects, in drawing up plans and specifications for building and construction work, usually prescribe quantities of materials considerably in excess of the quantities which theoretically would be considered necessary for the purpose if exact knowledge concerning the properties, behavior, and permanence of the materials to be used were available; and it is fair to estimate that if the investigations under way can supply this information, they may be instrumental in reducing the cost of the construction work of the Government as much as 10 per cent on its present estimates.

As a result of several conferences among the representatives of the Government bureaus having in charge this construction work, it was decided that in view of the convenience and economy with which concrete might be more largely used in this work, and the lack of exact knowledge concerning its real properties and behavior and especially its strength and permanence under different conditions, concrete, reinforced concrete, and the constituent materials available for making it should receive a large share of attention in connection with the investigations provided for by Congress.

The importance of this work was further emphasized by the fact that a large quantity of this material might be needed in connection with the construction work of the Isthmian Canal, the Reclamation Service, the Corps of Engineers of the Army, and the Supervising Architect's Office. At that time attention was further called to the fact that inasmuch as a considerable period of time (from two to three years) would elapse in the investigations of concrete before any one series of tests could be completed-owing to the changes that concrete might undergo during periods of seasoning these investigations should be begun immediately and pushed vigorously in order that the results might be available at the earliest practicable date for important construction work then being planned by these several branches of the Government service.

For the reasons above outlined, during the last two years the larger part of the appropriation for the investigations of structural materials has been devoted to an investigation of the character and distribution of the constituent materials available for concrete construction at centers where these materials were to be needed by the Government; the character and properties of the concrete and reinforced concrete made from these materials; such general properties

་་་

of concrete as its strength, porosity, permanence, and fire-resisting qualities; the more efficient methods of reinforcing concrete for different purposes; and the behavior of concrete and reinforced concrete under different treatment with salt or fresh water, acids, electric currents, fire, etc.

The general plan of operations in these investigations involves (1) the obtaining of information concerning the nature and extent of the deposits of sand, gravel, and stone which appear to be available for the purpose of making concrete at or near the centers where Government building and construction work are to be undertaken; (2) the collection of samples, ranging from a few tons to a carload in quantity, of these sands, gravels, or stone which would be representative of the larger deposits available for actual use, and the shipment of these samples to the central laboratory at St. Louis; (3) the testing of these materials, not only by chemical and physical examination of the materials themselves, but also by mixing them with a typical cement and using these mixtures in the making of blocks, beams, etc., of concrete and reinforced concrete under a variety of conditions; (4) the testing of the steel used in making the reinforced-concrete masses; (5) the seasoning of these masses for different periods of time, under a variety of conditions; and (6) the testing of these masses from time to time in such manner as to determine their different properties and their suitability for different classes of building and construction work.

Perhaps the controlling reasons for asking that the Federal Government provide for these general investigations are the following: (1) The building and construction work of the Government greatly exceeds that of any State, corporation, or individual. (2) This work by the Government, being done in all parts of the country under many different conditions, calls for the solution of a far larger number and variety of general problems than may be called for in connection with the work of any State, corporation, or individual; and therefore the information which is in this way gained for the use of the Government, and which it pays the Government to obtain for use in its own work alone, is of value to the States, municipalities, and the whole people of the country in connection with their own building and construction work; provided that the results of the investigations are published in such a way as to become available for the use of the general public. (3) The investigations conducted by the Government are presumably disinterested, there being no other interest to be served than the acquirement of facts for public use; and in view of the varied conditions under which these results are to be used, and the ease with which the Federal Government can obtain results of similar investigations in foreign countries, this Government work should be and presumably is conducted with

sufficient thoroughness and on a sufficiently comprehensive plan to make the results also valuable for the use of the general public. (4) There is less occasion for duplication when these investigations are conducted by the Federal Government, because of this thoroughness and comprehensiveness. If this work were done by the States, municipalities, or individuals, each for its own purposes, there would be an extensive and unnecessary duplication in labor, cost, and time. The above statement applies only to these general investigations of structural materials. In addition to these, many special tests of local materials will naturally be desired by each State or municipality or private individual; and such tests, having only a local application, of course should be made or paid for by the State or persons concerned.

As an illustration of the thoroughness with which those in charge have endeavored to conduct the investigations called for in connection with this testing of the materials to be used by the Government, the fact may be mentioned that during the two fiscal years ending June 30, 1907, the number of tests and determinations made aggregated 35,500; also that in certain investigations of plain and reinforced concrete made in connection with the work of the Supervising Architect of the Treasury Department, more than 1,000 concrete beams each 13 feet by 8 by 11 inches) have been made, representing different types of mixtures, reinforcement, etc. These beams are now being tested at intervals to determine the varied conditions in their makeup and the effects of age and seasoning.

Another of the numerous series of investigations, still under way, for the Supervising Architect's Office, is that in relation to the fireresisting qualities of the materials needed for use in the construction of the public buildings--a work which requires the testing of many materials under many different conditions. As illustrating the importance of this investigation in relation to the general public, attention may be called to the fact that the fire losses in the United States, including not only property destroyed, but maintenance of fire departments, payment of insurance premiums, so-called curative agencies, and other incidentals, amounted to over $500,000,000 in 1906, or over 80 per cent of the value of the total new building construction. This is equivalent to an annual tax of over $6 per capita. By comparison, in six of the larger European countries the fire losses average only 33 cents per capita, and this in spite of the fact that the appliances and facilities for fighting fires in the United States are greatly superior to those in European countries. This discrepancy in the fire losses is due to the more extended use in other countries of building materials which are more or less fireproof.

The first report issued by the structural-materials division (Bulletin No. 324) related to the effects of the San Francisco earthquake

ལ་

and fire on buildings and materials. The present report embraces a statement of the organization and equipment of the division. The next will relate to the studies of the constituent materials (sands, gravels, stone, and cement) used in the construction of concrete masses, samples of these materials having been collected in different parts of the country and examined in connection with this general investigation.

Other reports now ready for publication will embrace the results of other lines of investigation in relation to concrete and to reinforced-concrete masses made of these materials mixed with the typical Portland cement described in this report.

In connection with the taking up of any new line of investigation, much time is necessarily required for the preliminary work of procuring equipment, training experts to conduct the investigations, determining the exact methods which are to be employed, and bringing the establishment to a high degree of efficiency. This having been accomplished at the structural-materials laboratories, the work should hereafter go forward rapidly and in a satisfactory manner. There is serious need, however, of additional equipment for testing larger masses of material, for investigating clays and clay products, and for testing the fire-resisting properties of materials.