BULLETIN £49, U. S. DEPARTMENT OF AGRICULTURE. 



Grimes, J. F., Kentucky. 

 Hinderlite, H. B., North Carolina. 

 Hutchinson, G. W., Delaware. 

 Jackson, F. H., Bureau of Public Roads. 

 Lang, F. C, Minnesota. 

 Learnt, H. Walter, Maine. 

 Maddocks, Frederick T., California. 

 Martin, W. D., Ohio. 

 Milburn, Henry M., Bureau of Public 

 Roads. 



Purrington, W. F., New Hampshire. 



Rea, A. S., Ohio. 



Roman, F. L., Illinois. 



Rossell, F. C, Maryland. 



Saunders, R. L., Connecticut. 



Seaton, R. A., Kansas. 



Smith, E. B., Bureau of Public Roads. 



Terrell, D. V., Kentucky. 



Ulman, Malcolm H., Pennsylvania. 



Withey, M. O., Wisconsin. 



The important recommendations which resulted from the confer- 

 ence are due largely to the painstaking and effective work of the 

 testing engineers who participated. 



Standard methods of sampling and testing the materials employed 

 in highwa} T construction were adopted, as set forth in this bulletin. 

 It wall be noted that the standard methods adopted by the American 

 Society for Testing Materials have been accepted so far as the field 

 has been covered by that society. In some of the methods minor 

 revisions of the A. S. T. M. standards have been made, and where 

 that has been done, the notation that follows the title of the test or 

 method indicates that there has been such revision. 



For tests that have not been standardized by the American Society 

 for Testing Materials, the methods of testing set forth in Bulletins 

 314, 347, and 555 of the U. S. Department of Agriculture, contributed 

 by the Bureau of Public Roads, have been adopted for the most 

 part. Several new tests and revisions of old tests are suggested for 

 trial, to be adopted later if they prove to be satisfactory. 



It will be noted that for the convenience of testing departments, 

 there is given the full text of all tests usually employed in a highway 

 department testing laboratory. This has been done because it is 

 believed it will save time and avoid confusion to have all of this 

 material available in a single volume. 



The tests set forth in this bulletin are recommended as official 

 standards by the committee on tests and investigations of the Amer- 

 ican Association of State Highway Officials, and this recommenda- 

 tion is concurred in by the Bureau of Public Roads. 



The recommendations of the conference were assembled and 

 arranged by T. R. Agg, chairman of the committee on tests and 

 investigations of the American Association of State Highway Offi- 

 cials, and A. T. Goldbeck, engineer of tests of the Bureau of Public 

 Roads. 



