DUST PEEVENTION AND ROAD PRESERVATION, 1915. 31 



paving culvert inlets and outlets with gneiss spalls where this was 

 necessary. Two existing catch basins which were considered too 

 small for the service demanded of them were reconstructed and 

 enlarged and two new catch basins were constructed at other points. 

 After the foundation course was thoroughly compacted by rolling, 

 an entirely new wearing surface was constructed. The wearing 

 surface consists of a 3-inch depth of fresh limestone (loose measure- 

 ment) bonded together with bituminous material. The same 

 bituminous material was used throughout, but two different methods 

 were employed. From station + 00 to station 19 + 00 and from sta- 

 tion 21+00 to station 38 + 13^ straight oil-asphalt was used, while 

 for the remaining 200 feet between stations 19 and 21 a sand-oil- 

 asphalt grout was used. 



The Oil-Asphalt Section (Penetration Method). 



Location: Station 0+00 to station 19+00 and station 21+00 to station 38+13J. 

 Area: 6,421 square yards. 



These sections comprise a total area of 6,421 square yards and were 

 constructed in accordance with the common penetration method; 

 that is, the penetration course of stone was spread and rolled, bitumen 

 appHed, screenings spread, and the surface finished with a seal coat 

 of bitumen and stone chips. 



One and a half gallons of bitumen per square yard was used in the 

 penetration course and approximately one-half gaUon per square 

 yard in the seal coat. A total of 7,150 gallons of bitumen was used 

 on the first section and 6,328 gallons on the second section, which 

 gives a total average quantity per square yard of 2.012 gallons and 

 2.16 gallons, respectively, for the two sections. Table 31 shows the 

 analysis of the oil-asphalt used, and Table 32 the cost of the work, 

 which was done by contract. 



Table 31. — Analysis of oil-asphalt} 



Specific gravity 25725° C 1. 024 



Melting point °C 50 



Penetration 25° C, 100 grams, 5 seconds 105 



Loss 5 hours at 163° 0., 20 grams, per cent 19 



Penetration of residue ^ as above 64 



Percentage of total bitumen insoluble in 80° naphtha 25. 77 



Fixed carbon, per cent 15. 74 



Soluble in CSg (total bitumen), per cent 99. 70 



Organic matter insoluble, per cent 18 



Inorganic matter insoluble, per cent 12 



Total, per cent 100. 00 



1 Fairly hard, glossy, sticky, semisolid. 



