UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 347 
Contribution from Office of Public Roads and Rural Engineering ^ y , 
£&$*&&». LOGAN WALLER PAGE, Director j£& m< &J'U 
Washington, D. C. PROFESSIONAL PAPER March 17, 1916 
METHODS FOR THE DETERMINATION OF THE PHYSICAL 
PROPERTIES OF ROAD-BUILDING ROCK. 
By Frank H. Jackson, Jr., Assistant Testing Engineer. 
CONTENTS. 
Page. 
Introduction 1 
Physical properties of road-building rock 2 
Physical tests of road materials 3 
Specific gravity, weight per cubic foot, 
water absorption 3 
Deval abrasion test 4 
Hardness test 6 
Page. 
Physical tests of road materials— Contd. 
Toughness test 11 
Cementing value test 15 
Compression test 22 
Appendix A.— Selection and shipment of 
samples 22 
Appendix B.— Equipment of laboratory 26 
INTRODUCTION. 
This bulletin is a partial revision of a former bulletin by Albert T. 
Goldbeck and Frank H. Jackson, jr., issued June 10, 1912. 1 The 
first bulletin dealt not only with the method of testing rock for 
road building, but also gave the results of laboratory tests obtained 
by the office on all rock samples received to July 1, 1911, together 
with the interpretation of those tests. It appears advisable to 
present complete results of tests by the office at rather frequent 
intervals, so that additional data may be promptly available for 
the general use of highway engineers. The present bulletin has thus 
been limited to a description of methods employed by this office for 
testing rock for road building, and is intended to serve as a more 
or less permanent laboratory manual for those who have occasion to 
make such tests. 
Although the methods of determining the physical properties of 
rock used in macadam road construction have remained essentially 
the same since the publication of Bulletin 44, experience gained 
» Office of Public Roads Bulletin No. 44, The Physical Testing of Rock for Road Building. 
17025°— Bull. 347—16 1 
