TABLE VI-COMPARISON OF IMPACT TESTS OF OLD TIME ASPHALT SURFACE MIXTURES, THOSE OF 1904 OF VARIOUS GRADING, AND PRESENT STANDARD MIXTURE.

70,354 N. Y. Stand. Mx. 1905 11.2% 17.8 12 ΙΟ

Bitu

Pass

100. 80. 50. 40. 30. 20. 10.

men.

200.

30,035

1885

8.3% 13.7 15 ΙΟ

27 12
20 13

8.7%

4 16

16 15

I I

I 2

7 28 16

1904

12. .0% 16.0

TABLE VII-IMPACT TESTS AT 78° F. OF ASPHALT SURFACE MIXTURES AFTER IMMERSION IN WATER FOR 3 MONTHS-USING ASPHALT CEMENT OF 65 PENETRATION (Bowen) or 45 PENETRATION (Dow).

THE COLLECTIVE PORTLAND CEMENT

EXHIBIT AND MODEL TESTING LABORATORY OF THE ASSOCIATION OF AMERICAN PORTLAND CEMENT MANUFACTURERS, AND THE RESULTS OF TESTS AT THE LOUISIANA PURCHASE EXPOSITION, ST. LOUIS, MO.*

BY RICHARD L. HUMPHREY.

Great expositions mark the progress made in the industrial world, and emphasize the advance in particular lines. The Louisiana Purchase Exposition was no exception. Those who were fortunate in being able to attend the Exposition at Chicago in 1893 and St. Louis in 1904 doubtless observed the progress which had been made in the branches in which they were especially interested. To those interested in cement, a very noticeable feature of the former was the absence of an American Portland Cement Exhibit, and the elaborate German exhibits of this material. This was naturally to be expected at a period when American Portland cement was hardly known and was regarded as of doubtful quality, while German Portland cement was universally used and was held in very high regard. The total consumption of Portland cement in 1903 was 3,264,801 barrels, of which 82 per cent. was of foreign and only 18 per cent. of domestic manufacture. In the decade which has since elapsed a great change has taken place in the production and consumption of American Portland cement. The production has increased 450 per cent., while the importations have fallen off about 73 per cent.; the consumption now exceeds 26,505,881 barrels, and this country has grown from one of the smallest to one of the largest Portland cement producing countries of the world.

* Presented jointly to the Association of American Portland Cement Manufacturers and the American Society for Testing Materials.

It was quite appropriate that this remarkable growth of the cement industry in America should be fittingly exploited at St. Louis, and it was natural that this exploitation should be made by the American Portland cement manufacturers in a collective exhibit. Such an exhibit formed the gateway to the mining gulch of the Exposition and was one of the most attractive of the outside individual exhibits. The fact that there were no foreign cement exhibits worthy of note, served to emphasize the withdrawal of the foreign Portland cement from the American market, resulting

from the development of the American Portland cement industry. In yet another particular was this collective exhibit noticeable. In 1893 the American Portland cement manufacturer, while not openly hostile to the inspection and testing of his product, was nevertheless not a strong advocate and frequently rebelled against the restrictions placed on him by the testing engineer. Yet it was because of this continual raising of requirements which compelled the manufacturer to improve his product, that he occupies a premier position in the cement industry to-day. We now find the manufacturer no longer the opponent but the firm advocate of

proper methods for testing. This new attitude was shown in the equipment and operation of the Model Testing Laboratory in which was exploited the methods for testing cement proposed by the special committee of the American Society of Civil Engineers, whose report was distributed gratuitously. Only those who had an active part in the erection of buildings and installation of exhibits at a great exposition can appreciate the vexatious delays occasioned by unforseen difficulties; this was particularly true of the cement exhibit.

It was originally intended that the work of construction should be carried on during the Exposition as a working exhibit. To secure greater advantages in an educational way it was subsequently decided to complete it as soon as possible, but before this could be accomplished the Exposition was well towards its close. The buildings, and the installation of the equipment of the laboratory and of the other exhibits were quickly completed and the whole placed in a working condition.

The completed Exhibit formed a comprehensive exposition. of the Portland Cement Industry, comprising:

I. A collection of the raw materials from which Portland cement is manufactured, together with samples of this material taken in various stages of manufacture, to the finished product.

2. A collection of the various sands, gravels, cinders, broken stone and metal used in concrete, together with photographs and models of structures built of concrete in all parts of the world.

3. A library of books and files of the various technical journals devoted to cement, mortar and concrete.

and,

4. A completely equipped model testing laboratory.
5. A collection of machines for mixing and molding concrete;

6. A collection showing the many forms in which Portland cement is used.

The exhibit building, one of two permanent structures, which has been presented to and accepted by the Park Commission of the City of St. Louis, Mo., is an excellent example of reinforced