DUST PREVENTION" AND ROAD PRESERVATION, 1915. 63 



Section No. 8. — ^Refined Watee-Gas Tar Preparation, Surface Treatment. 



This section presents a very un-uniform appearance over most of 

 the area. The aggregate now shows and the surface is ready for a 

 seal coat. This treatment was postponed dm-ing the past season 

 only at the expense of considerable repair. In a few places there is 

 a heavy mat that appears to have been pushed up by traffic, but 

 elsewhere the mat is generally worn off. 



Section No. 9. — Asphaltic Petroleum, Surface Treatment. 



During the past season, sections 9 and 10 were re-treated uniformly. 

 At the time of inspection they much resembled each other, but 9 is 

 in better general condition. There are only three or four breaks 

 through the mat and, though wavy and uneven, the surface is nearly 

 intact. The marked difference between the east and west halves 

 of the section is not nearly so great as in No. 10. Table 63 gives an 

 analysis of the bituminous material used, and the cost of this re-treat- 

 ment is given in Table 64. 



Table 63. — Analysis of asphaltic petroleum used on sections 9 and 10. 



Specific gra^dty, 25°/25° C 0. 963 



Flashpoint, °C 31 



Burning point, °C 84 



Viscosity at 25° C, 50 c.c, Engler specific 128. 4 



Loss, 5 hours, at 163° C, 20 grams, per cent 23. 14 



Float test on residue, 32° C. (time) 2^ 37'" 



Float test on residue, 50° C. (time) V 4/^ 



Percentage of total bitumen insoluble in 86° B. naphtha 5. 96 



Fixed carbon, per cent 4. 62 



Soluble in CS, (total bitumen), per cent 99. 94 



Organic matter insoluble in CSj, per cent 0. 04 



Inorganic matter insoluble in CS2, per cent 0. 02 



Total 100. 00 



Section No. 10. — PiEsidual Petroleum, Surface Treatment. 



This experiment continues to be the most troublesome section of 

 the entire project. Reference to previous reports will disclose that 

 it has had repeated attention, being once scarified and rebuilt and 

 once re-treated. In the spring of 1915, after having been very 

 muddy during the preceding winter, it had an irregular wavy mat 

 and there were numerous spots where the aggregate was exposed. 

 It rapidly disintegrated at these points and considerable repair work 

 became necessary. Fuially, on August 16 to 18, 1915, a second 

 re-treatment, using asphaltic petroleum, was given. This re-treat- 

 ment was extended over experiment No. 9 and its details are given 

 in the description of that section. At the time of inspection the 

 west half of the section agaiost the track was in fair condition, but 



