36 BULLETIN 105, U. S. DEPARTMENT OF AGRICULTURE. 



thus trimming off the humps and filling depressions the general con- 

 tour of the road was greatly improved. In December all bare places 

 were covered with a light application of the water-gas tar preparation 

 No. 1 the analysis of which is given in Table 2, and screenings. 



The total cost of maintaining and repairing the surface during the 

 year was $40.41, or 1.19 cents per square yard for the entire area. 



SUPPLEMENTARY REPORT OF EXPERIMENTS MADE AT JAMAICA, N. Y., 



1911. 



OIL-CEMENT CONCRETE, OIL ASPHALT, TAR, AND FLUXED NATD7E ASPHALT. 



The original report of these experiments was published in Circular 

 Xo. 98, and the report of an inspection made December 19, 1912, with 

 repairs to date, was given in Circular Xo. 99. The experiments were 

 again inspected and repaired in June, 1913, and the following report 

 covers the work done at that time and the condition of the sections 

 when again inspected on December 16, 1913. 



Experiment No. 1. — Oil-cement concrete. 



When inspected in June it was found that practically all of the vari- 

 ous carpet coats which were applied to this section in 1912 were gone 

 with the exception of the refined coal-tar section. About 75 per cent 

 of the carpet coat on this section was in fair condition. 



The surface of the pavement showed the effect of the wear of traffic 

 and contained many shallow depressions among which the following 

 were so deep as to be practically through the concrete: Station -1- 98, 

 4 feet by 5 feet, against the south side of the pavement; station + 

 75, 2\ feet by 3 feet, 8 feet from the south edge of the pavement; sta- 

 tion + 77, 1 foot by \\ feet, 13 feet from the south edge of the pave- 

 ment; station + 77, 1 \ feet by \\ feet, 16 feet from the south edge of 

 the pavement; station + 03, 2\ feet by 4 feet, 18 feet from the south 

 edge of the pavement. 



The expansion joint at station + 97 was in perfect condition and 

 had completely protected the abutting ends o*f the concrete. 



Repairs were made as follows: The entire section was gone over 

 and all the old flush coat that could be loosened readily with pick and 

 shovel was removed. The shallow depressions, 1 to \\ inches in 

 depth, were filled to grade with f-inch stone. The deep depressions 

 were cut out to the subgrade to the size above stated and filled with 

 1^-inch stone, the voids of which were filled with sand and refined 

 coal tar. The depression at station + 03 was repaired with paving 

 brick. The entire section was then surface-treated with bituminous 

 materials as follows: From station + 00 to station + 57, refined 

 coal tar, 0.30 gallon per square yard; from station + 57 to station 

 + 97, water-gas tar preparation Xo. 1, 0.44 gallon per square yard; 

 and from station. + 97 to the east end of the section, water-gas 



