19 BULLETIN 586, U. S. DEPARTMENT OF AGRICULTURE. 
tion was worn down about 24 inches below the surface of section 4, 
where a bituminous binder was used. 
Holes were dug at 225 feet from the north end and 175 feet from 
the south end of the section and showed the depth of the slag to be 
about 64 inches. A sample of the slag showed (1) that the slag 
particles were carbonated on the surface, (2) that the pores of the 
slag contained calcium hydrate crystals, (3) a cementing value of 63. 
Section No. 4, blast-furnace slag and refined coke-oven tar—The 
south 50 feet remained in good condition, except that the surface 
was slightly wavy. The remainder of the section, which was reported 
as having failed at the time of the inspection of December, 1915, 
had been covered over with slag sand, and is no longer of experi- 
mental value. A sample of the new slag sand showed a cementing 
value of 67. 
Section No. 5, blast-furnace slag—The south 90 feet of this section 
was in uniformly good shape. The remainder of the section, through 
the cut, was worn into ruts and showed an accumulation of fine 
material on the surface. The ruts noted at the time of the inspection 
of December, 1915, 165 feet and 135 feet, respectively, from the 
south end, had increased in depth to about 3 inches. For the rest 
of the distance the ruts were broad and shallow. The north end of 
the section still was about 14 inches below the surface of section 4. 
Section” No. 6, blast-furnace slag—This section had not changed in 
appearance since the inspection of December, 1915, except that an 
accumulation of fine material had collected along the east edge of the 
road. A hole dug about 150 feet from the south end of the section 
showed the depth of the slag to be about 94 inches. A sample of 
the slag showed (1) that the particles of slag were carbonated on the 
surface and (2) a cementing value of 45. 
Section No. 7, blast-furnace slag and open-hearth slag—The north 
one-third showed little evidence of wear and the surface was firm and 
well bonded. The south one-third showed considerable wear along 
the wheel tracks, but the top course did not appear to have worn 
through, and the surface still was firm and well bonded. The depres- 
sion over the culvert near the south end had flattened out, due to 
the wearing action of traffic, but had not been repaired. The middle 
one-third of the section was resurfaced with slag sand in the fall of 
1916, and probably will not be of any further service as an experi- 
-ment. It was evident that the surface had become rather rough and 
badly rutted before the slag sand was applied. __ 
Holes dug at 50 feet and 100 feet from the south end showed the 
depth of the slag to be about 9 inches. A sample of the slag showed 
a cementing value of 65, carbonated surfaces, and practically no 
evidence of the open-hearth screenings used in the original con- 
struction. 
