DUST PKEVElil^TTOJSr AND ROAD PRESERVATION, 1915. 



55 



SUPPLEMENTARY REPORT OF EXPERIMENTS AT WASHINGTON, D. C, 



1912. 



TAR PREPABATION AND OILS, SURFACE TREATMENT. 



The original report of these experiments was published in Circular 

 No. 99 of the Office of Public Roads, and inspection reports have 

 appeared in United States Department of Agriculture Bulletins Nos. 

 105 and 257. The following report describes the condition of the 

 pavement before re-treatment, the extent of the repairs during 1915, 

 and the condition of the experiments when inspected on February 

 25, 1916. 



Section No. 1. — ^Refined "Water-Gas Tar Preparation. 



Section 1 appeared intact and required neither repairs nor re- 

 treatment during the summer of 1915. 



Section 2 raveled locally in some spots to a depth of 2 inches or 

 more. Most of these failures were along the wheel tracks. Only one 

 was at the edge, and this failure was probably due in some measure 

 to defective drainage. The mat was worn unevenly, and over con- 

 siderable areas was entirely gone. The entire section was repaired 

 with penetration patches, in which an oil asphalt and limestone were 

 used, top-dressed with trap chips. 



The cost of patching was : 



Labor $9.50 



Materials 8. 10 



Total 17. 60=$0.0155 per square yard. 



The section was then re-treated with the same materials originally 

 used. An analysis of the asphaltic petroleimi is given in Table 57. 



Section No. 3.— Residual Petroleum. 



Section 3 had been persistently muddy during the last winter and 

 spring. The oily mud had been forced aside from the prevailing 

 wheel tracks, so that many bare places and depressions existed, and 

 one long rut about 1^ inches deep and 8 to 10 inches wide had devel- 

 oped along the north edge for some 75 or 80 feet at the west end. 



Table No. 56. — Cost of preliminary repairs per square yard. 



Section. 



Labor. 



Materials. 



Total. 



1 









2 



10.0084 

 .0109 



$0.0071 

 .0073 



$0.0155 

 .0182 



3 



4 











