44 



BULLETIN 407^ U. S. DEPARTMENT OF AGKICULTUEE. 



timbers were then removed and limestone shoulders, 6 inches thick 

 and 2 feet wide, compacted by rolling, were constructed to support 

 the sand-asphalt surface. Table 45 gives typical analyses of the 

 sand-asphalt mixture. The data relating to materials and cost, given 

 in Table 47, do not differentiate between the various sections, but are 

 presented just as if the cost were uniform over the entire experiment, 

 irrespective of the varying thickness of the wearing surface. 



Table 44. — Analysis of oil-asphalt ^ used in experiment No. 2. 



Specific gravity 25°/25° C 1. 041 



Melting point ° C 64 



Penetration, 25° C, 100 grams, 5 seconds 50 



Loss, 5 hours, 163° C, 20 grams, per cent 0. 06 



Penetration of residue ^ as above 38 



Per cent of total bitumen insoluble in 86° B. naphtha. 29.45 



Fixed carbon, per cent 17. 50 



Soluble in CSg (total bitumen), per cent 99. 86 



Organic matter insoluble, per cent 10 



Inorganic matter insoluble, per cent 04 



Total, per cent 100. 00 



1 Hard, sticky, glossy, semisolid. 



Table 45. — Typical analyses of sand-asphalt mixtures used in experiment No. 2. 



II. 



III. 



IV. 



V. 



Bitumen (soluble in CS2) 



Mineral aggregate: 



Retained on lO-mesh sieve 



Passing 10-mesh sieve, retained on 20-mesh sieve. 

 Passing 20-mesh sieve, retained on 30-mesh sieve. 

 Passing 30- mesh sieve, retained on 40-mesh sieve. 

 Passing 40-mesh sieve, retained on 50-mesh sieve. 

 Passing 50-mesh sieve, retained on 80-mesh sieve. 

 Passing 80-mesh sieve, retained on 100-mesh sieve. 

 Passing 100-mesh sieve, retained on 200-mesh 



sieve 



Passing 200-mesh sieve 



Average percentage of bitumen (soluble in CS2) . . 



Per cent. 

 8.41 



0.1 

 1.6 

 4.9 

 10.8 

 13.1 

 31.7 

 12.9 



15.7 

 9.2 



Per cent. 

 8.27 



0.0 

 2.5 

 4.7 

 10.4 

 12.3 

 32.3 

 11.8 



19.7 

 7.2 

 9.25 



Per cent. 

 9.87 



0.1 

 1.4 

 5.1 

 10.9 

 13.5 

 33.3 

 12.5 



14.2 

 9.0 



Per cent. 

 8.16 



0.0 

 1.1 

 4.7 

 9.4 

 13.7 

 33.0 

 12.1 



12.0 

 14.0 



Per cent. 

 10.28 



0.1 

 1.5 

 4.3 



7.1 

 16.0 

 33.4 

 12.4 



18.4 

 6.9 



The cost data given in Tables 46 and 47 are based on the following 

 scale of wages and unit prices : 



Foreman, per 10-hour day, $3.25. 



Subforeman, per 10-hour day, $1.25. 



Skilled labor, per 10-hour day, $1.75. 



Common labor, per 10-hour day, $1. 



Teams, per 10-hour day, .$3. 



Asphaltic oil, f. o. b. Baltimore, Md., per gallon, $0.06. 



Oil-asphalt, f. o. b. Baltimore, Md., per ton, $12.50. 



Freight on oil-asphalt, Baltimore, Md., to Ocala, Fla., per ton, $6.72. 



