UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 370 



Contribution from Office of Public Roads and Rural Engineering 

 LOGAN WALLER PAGE, Director 



Washington, D. C. 



PROFESSIONAL PAPER 



July 20, 1916 



THE RESULTS OF PHYSICAL TESTS 

 OF ROAD-BUILDING ROCK 



By 



PREVOST HUBBARD, Chemical Engineer, and FRANK H. 

 JACKSON, Jr. , Assistant Testing Engineer 



CONTENTS 



Introduction 



Agencies Causing Road Deterioration . . 

 Factors Influencing the Selection of Rock 



for Road Building 



Physical Properties of Road-Building Rock 

 Variations in Results of Tests 



Page 

 1 



Page 



Interpretation of Results of Physical 

 Tests 9 



Table IV. — Geographical Distribution of 

 Samples Tested 12 



Table V.— Results of Physical Tests of 

 Road-Building Rock <, . 13 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 



1916 



