UNITED STATES DEPARTMENT OF AGRICULTURE 



..314 



Contribution from Office of Public Roads and Rural Engineering 

 JSvrf'^fU LOGAN WALLER PAGE, Director J&$*^JU 



Washington, D. C. 



PROFESSIONAL PAPER. 



December 10, 1915 



METHODS FOR THE EXAMINATION OF BITUMI- 

 NOUS ROAD MATERIALS. 



By Prevost Hubbard, Chemical Engineer 

 Charles S. Reeve, Chemist. 



and 



CONTENTS. 



Page. | 



Classification of materials 2 



Scheme of examination 2 



Specific gravity determination 4 



Specific viscosity determination 7 



Float test 9 



Penetration test , 11 



Melting point determination : 14 



Flash and burning points 16 



Volatilization test 19 



Distillation test 21 



Dimethyl sulphate test 25 



Page. 



Bitumen soluble in carbon disulphide' 25 



Bitumen insoluble in paraffin naphtha 28 



Bitumen insoluble in carbon tetrachloride ... 30 



Fixed carbon 30 



Paraffin scale 32 



Extraction of bituminous aggregates 35 



Grading the mineral aggregate 3S 



Voids in the mineral aggregate 39 



Bituminous emulsions 41 



Appendix 43 



INTRODUCTION. 



This bulletin is the first revision of Office of Public Roads Bulletin 

 No. 38, which was issued July 27, 1911. Its object is to present a 

 i iption of methods now in us? by the Office of Public Roads and 

 Rural Engineering for the examination of bituminous road materials 

 in such form that, with a little practice and proper equipment, such 

 examinations may be madeby any intelligent person. The various tests 

 have, therefore, been described rather more in detail than would be 

 necessary if they were intended for the use of chemists only; and illus- 

 trations of practically all of the apparatus required have also been 

 included. 



Since the publication of Bulletin No. 38 considerable progress has 

 been made in the standardization of methods of examining bituminous 

 road materials. Many of the methods described in Bulletin No. 38 

 bave been generally adopted. Certain of these methods have, how- 

 ever, been improved during the past four years and the constant 

 demand for this bulletin lias led to its present revision. Tin; 

 <-!iaiigs and additions QOted below are the result of investigations 

 conducted in the laboratories of the office and of cooperative work 

 wii h certain technical societies. 



Bui] .M 15 1 



