62 BULLETIN 407, IT. S. DEPARTMENT OF AGEICULTURE. 



scarifying a section about 40 feet long so as to include the entire 

 Chevy Chase Club entrance, then using the scarified material as a 

 base and laying a new wearing surface of bituminous concrete of the 

 analysis given in Table 61. A sample of the fluxed native asphalt 

 used in the misture gave the analysis shown in Table 62. At the 

 time of inspection this intersection was in perfect condition. The 

 total area of the intersection, as rebuilt, was 100 square yards, and 

 the work was done by contract at a cost of $150. 



Table 61. — Analysis of bituminous concrete used in resurfacing a portion of section 6. 



Per cent. 

 Bitumen soluble in CSg (total bitumen) 9.5 



Mineral aggregate passing f-inch screen, retained on ^-inch screen 2. 



Mineral aggregate passing i-incb screen, retained on ^-incb screen 11. 



Mineral aggregate passing J-inch. screen, retained on |-inch screen 15. 3 



Mineral aggregate passing J-inch screen, retained on 10-mesh sieve 5. 6 



Mineral aggregate passing 10-mesh sieve, retained on 20-mesli sieve 14. 1 



Mineral aggregate passing 20-mesh sieve, retained on 30-mesh sieve 9. 7 



Mineral aggregate passing SO-meeh sieve, retained on 40-mesli sieve 9. 3 



Mineral aggregate passing 40-mesli sieve, retained on 50-mesh sieve 7. 4 



Mineral aggregate passing 50-mesh sieve, retained on 80-mesh sieve 11. 5 



Mineral aggregate passing 80-mesh sieve, retained on 100-mesh sieve 2. 8 



Mineral aggregate passing 100-mesh sieve, retained on 200-mesh sieve 3. 7 



Mineral aggregate passing 200-mesh sieve 7. 6 



Total 100. 



Table 62. — Analysis of fluxed native asphalt used in bituminous concrete, section 6. 



Specific gravity, 25°/25° C 1. 070 



Melting point, °C 55 



Penetration 25° C. 100 grams, 5 seconds 50 



Loss at 163° C. 5 hoiu-s, 20 grams, per cent 2. 51 



Penetration of residue as above 22 



Per cent of total bitumen insoluble in 86° B naphtha 26. 72 



Fixed carbon, per cent 12. 52 



Soluble in CSj (total bitumen), per cent 94. 85 



Organic matter insoluble in CS2, per cent 1. 80 



Inorganic matter insoluble in CSj, per cent 3. 35 



Total, per cent 100. 00 



Section No. 7, A and B. — Oil- Asphalt, Penetration Method. 



Section A is much more distinctly mosaic than B and a little 

 smoother. It has a few potholes and will probably require a seal 

 coat in the spring. The south half of B still retains the mat fairly 

 intact, but it appears to be worn very thin. The surface is fuU of 

 short, irregular waves, especially on the north half, where there are 

 many bare places and a few potholes. Where cleaned the surface 

 shows a somewhat mosaic appearance and toward the north end 

 becomes noticeably smooth and regular. 



