DUST PBEVE^TIOJST AXD EOAD PRESEKVATIO]Sr, 1914. 11 



Float test at 32° C. (time) 22" 



Float test at 50° C. (time) 14" 



Loss, 5 hours at 163° C, 20 grams per cent. . 16. 82 



Float test on residue at 32° C. (time) 6 / 30" 



Float test on residue at 50° C. (time) V 46" 



Percentage of total bitumen insoluble in 86° B. naphtha 9. 37 



Fixed carbon per cent. . 4. 64 



Soluble in CS 2 (total bitumen) do 99. 87 



Organic matter insoluble do .05 



Inorganic matter insoluble do .08 



Total do 100. 00 



Method. — The rock course was rolled until firm, after which dust- 

 less screenings were scattered lightly over the rock surface, partly 

 filling the larger voids. The rate of application of the bitumen was 

 1.39 gallons per square yard at an average temperature of 105° C. 

 The bitumen flowed readily and penetrated completely when allowed 

 to stand for a sufficient time. Frequent rains during the treatment 

 of this section handicapped the performance of the work and at times 

 necessitated sanding immediately after the application of the bitumen. 



A. From stations 3 + 68.8 to 5 + 15.5, sand was used as a top dress- 

 ing. This section bled profusely and unevenly for about two weeks 

 after construction, forming a sand mat of uneven thickness. In those 

 areas where there was no bleeding the surface had a light brown color 

 and the bitumen seemed to have become somewhat absorbed in the 

 rock itself. Traffic was permitted the use of this portion of the 

 experiment immediately after construction. 



B. From stations 5 + 15.5 to 5 + 84, dustless screenings were used 

 as top dressing and there was no bleeding over this area. Traffic did 

 not use this section until three weeks after construction. 



Experiment No. 5 (Oil-Asphalt — Penetration Method). 



Location: Station 5+84 to station 0+32=48 feet. 

 Area: 80 square yards. 



Table 7.- — Analysis of oil-asphalt. 



Specific gravity, 25725° C 1. 008 



M <•! i i Dg point °C. . 58 



Penetration, 25° C, 100 grams, 5 seconds m. m.. 10. 2 



Loss, 5 hours at 163° €., 20 grams per cent. . . 44 



Penetration of residue, as above 7. 9 



ntage of tof;d hil.unif.Ti in:-o!iiU<; in S<;' J |i. naphtha 23. 97 



Fixed carbon per cent. . 11. 06 



Soluble in CS a (total bitumen) do 99. 86 



dc matter insoluble do L0 



tnic matter insoluble do 04 



Total do. ... I ()(). (io 



