50 BULLETIN 401, XJ. S. DEPAETMENT OF AGRICTJLTUBE. 



Experiment No. 3. — Asphaltic Petroleum, Cold Application 



During the winter of 1914 the surface cracked and crumbled in 

 places as during the preceding winter, and in many places mud 

 formed. This ironed out Tmder traffic, but the mat was so thin and 

 broken that a second re-treatment became necessary and was applied 

 June 25 to 30, 1915. A short section at the north end was not 

 finished until August 16-18. The work was done by hand, as described 

 in the last report, using the same bituminous material originally 

 appHed and torpedo sand similar to that used on experiment 7. 

 Table 49 shows the characteristics of the bituminous material used, 

 and cost data will be found at the end of this report. 



Table 49. — Analysis of asphaltic petroleum used on experiment S. 



Specific gravity, 25°/25° C 0. 932 



Flashpoint, °C 35 



Burning point, °C 70 



Viscosity, Engler, 50 c. c, at 25° C, specific 61. 9 



Loss, 5 hours, at 163° C, 20 grains, per cent 22. 94 



Float test of residue at 32° C, time 5' 53^' 



Float test of residue at 50° C, time 1^ 22^^ 



Percentage of total bitumen insoluble in 86° B. naphtha 13. 67 



Fixed carbon, per cent 7. 62 



Soluble in CS2 (total bitumen), per cent 99. 90 



Organic matter insoluble, per cent 10 



Inorganic matter insoluble, per cent 00 



Total, per cent 100. 00 



This experiment is becoming rough on one hill, where frequent 

 unusual repairs have had to be made, as described in an earher 

 report. Except for this the surface presents the same character- 

 istics as it did a year ago. During cold weather the mat crumbles 

 rather freely and at the first thaw mud is formed. If traffic is not 

 too heavy and the mud is not displaced the surface mat is restored 

 rapidly as the surface dries and generally assumes its corky nature. 

 If the mud is displaced to any marked degree, as is very hkely to 

 happen if there is a snow storm followed by a thaw, then the mat 

 is not restored along the wheel tracks and two broad, shallow ruts 

 are the result. The stone is soon exposed along these ruts and dis- 

 integration follows rapidly. At the time of inspection ruts had 

 formed along about 200 feet of this experiment at the same point 

 where they formed in the winter of 1914-15. 



It is planned to give this experiment a foin"th apphcation early 

 in the season of 1916. Except as noted above, the surface is smooth 

 and in essentially as good condition as at the time of construction. 



Experiment No. 4. — Residual Asphaltic Petroleum, Hot Application. 



This experiment continues to present the best appearance of any 

 of those still carrying the original treatment. No re-treatment was 

 necessary during 1915, but it is probable that one will be required 



