68 BULLETIN 40*7, U. S. DEPARTMENT OF AGEICULTUBE; 



been compacted by traffic, a surface treatment of ligbt asphaltic oil 

 was applied to the three sections. Section No. 3 is readily recognized 

 by its smooth, even surface and weU-preserved cross section. 



As these experiments are no longer comparable as types of bitumi- 

 nous macadam pavement, their behavior -will not be reported hereafter. 



SUPPLEMENTARY REPORT OF EXPERIMENTS AT YOUNGSTOWN, OfflO, 



1910. 



SLAG. SLAG AND LIME, SLAG AND WASTE SULPHITE LIQUOR PREPARATION, AND SLAG 



AND TAR. 



The original report of these experiments was pubhshed in Circular 

 No. 92 and subsequent reports of annual inspections are given in 

 Circulars Nos. 94, 98, and 99, Office of Pubhc Roads, and in U. S. 

 Department of Agriculture Bulletins Nos. 105 and 257. The follow- 

 ing is a report of the condition of the roadway on December 3, 1915. 

 The sections are discussed in the order of their section numbers, 

 beginning at Mahoning Avenue. With the exception of the tar-slag 

 section, the road was covered with a thin sheet of snow at the time of 

 the inspection, which concealed some of the surface details. 



Section No. 1. — Blast-Furnace Slag. 



The condition of this section has not changed appreciably during 

 the past year. The surface is somewhat worn and pulverized in the 

 middle of the road and wide, shallow ruts are noticeable in the wheel 

 tracks. These ruts are not so pronounced as in the next two sections, 

 however. Aside from these defects, the surface is smooth, uniformly 

 worn, and free from large protruding stones. 



Section No. 2. — Blast-Furnace Slag and Lime. 



The general condition of this section is about the same as that of 

 section No. 1. The ruts are somewhat more pronounced, particularly 

 the one on the west side of the traveled way, and a depression, which 

 was evidently due to wear, was noted about 50 feet from the north 

 end of the section. 



Section No. 3. — Blast-Furnace Slag and Waste Sulphite Liquor Preparation. 



Little change has taken place in the condition of this section dur- 

 ing the past year. About 100 feet from the north end two shallow 

 depressions have formed in the wheel tracks, and for 200 feet from 

 the north end the surface is worn and slightly depressed in the middle 

 of the road. The ruts referred to in the two preceding sections 

 extend to the top of the shght grade near the middle of this section; 

 The south half of the section, which hes on the grade, is noticeably 

 better than the north half and is one of the best preserved parts of 

 the entire road. 



