DUST PEEVENTIOJSr AND ROAD PRESERVATION, 1915. 



39 



After the surface covering of sand was spread, the shoulders and 

 ditches were reshaped and the road was opened to traffic. A few 

 days later the asphalt began to bleed freely, and the local road official 

 in charge covered the road surface with a heavy additional layer of 

 sand to absorb the exudation. 



The road was built on April 9 and 10, 1915, and was inspected 

 December 10, 1915. The surface had received practically no atten- 

 tion since the time of its completion. Along the center fine or crown 

 of the 9-foot surface the horses had worn a path from 1 to 2 inches 

 deep and about 14 inches wide, and two corresponding wheel ruts 

 extended the full length of the section. The path and ruts are largely 

 in a mass of loose sand, shghtly impregnated with bituminous material 

 from 1 to IJ inches deep which overHes a firm, hard course of bitu- 

 minized sand. It is evident that the bituminous material used in 

 the fourth layer was of too viscous a nature to assimilate the sand, 

 or was insufficient in quantity to bind the heavy layer of sand which 

 was spread to absorb the bleeding. Outside of the central traveled 

 portion the surface is less broken. 



The surface requires reshaping and a fight appfication of material 

 A to bituminize the loose sand thoroughly. The road will then be 

 scarred and rutted by traffic for several months, after which it should 

 be reshaped with a grader occasionally until it is finally compacted. 



Table 41. — Analyses of bituminous materials used in experiment at Jupiter, Fla., 1915. 



Material. 



A. 



Residual 

 asphaltic 

 petroleum. 



B. 



Fluxed 

 native 

 asphalt. 



Specific gravity, 2.5°/2.5° C 



Melting point, ° C 



Viscosity, Engler, 50 CO. at 100° C. specific 



Float test at 50° C. Ctime) 



Penetration at Z5° C. 100 grams, 5 seconds 



Loss at lfi3° C. 5 hours, 20 grams, per cent 



Float test of residue at 50° C. (time) 



Penetration of residue as above 



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

 Fixed carbon, per cent 



Soluble in CS2 (total bitumen), per cent. 



Organic matter insoluble, per cent 



Inorganic matter insoluble, per cent 



Total, percent. 



1.01 



63.9 

 2' 5" 



1.82 

 3' 34" 



21.22 

 12.61 



99.88 

 .12 



1.066 

 59 



48 

 3.43 



18 

 23.61 

 12.02 



95.48 

 1.77 

 2.75 



100.00 



COST DATA. 



This experiment was of too small extent for the cost data to be of 

 material value. The asphalt was donated, and the total labor cost 

 was only about Si 2.41, including the grading. This is at the rate of 

 about 8.2 cents per square yard, exclusive of the bituminous material. 



