DUST PREVENTION AND ROAD PRESERVATION, 1914. 41 



Section No. 4 (Blast-Furnace Slag and Refined Coke-Oven Tar). 



The middle third of this section has settled very unevenly. Sand 

 and slag chips have lodged in the depressions, from several of which 

 the tar has entirely disappeared; in others, the pavement itself is 

 disintegrating. The tar is hard and "dead," and the stone and tar 

 can be separated under heel pressure. The ridges between the de- 

 pressions are cracking. 



While not as uneven as the middle third, the two end thirds are 



beginning to fail. The surface is so full of irregularities that riding 



over it is uncomfortable. In no place does the surface seem to have 



failed, but the tar is dry and lusterless and can be readily separated 



from the stone. 



Section No. 5 ("Blast-Furnace Slag). 



Section No. 5 is still about 1£ inches below section No. 4 at their 

 junction. The northern two-thirds of this section is on a grade in 

 a cut which shows evidence of seepage water. The surface of the 

 road is rutted wider and deeper over this part of the section than 

 over any other part of the experiments. However, there is no indi- 

 cation of failure of the pavement through raveling in the ruts. The 

 south one-third of the section has a very satisfactory appearance; 

 the ruts are not more than one-fourth inch deep, and the surface 

 has a smooth, evenly worn, and uniform appearance. 



Section No. 6 (Blast-Furnace Slag). 



This section is wearing down into wide deep ruts. While in 

 general the east rut is more pronounced than the west, there are 

 several elongated depressions in the latter which have been swept 

 clean of their binder and look as though they would ravel when dry. 

 There are also three small spots in the section that seem to be the 

 result of settlement rather than wear. The entire surface is mottled 

 with large stone about 3 inches in diameter, protruding above the 

 general surface. 



Section- No. 7 (Blast-Furnace Slag and Open-Hearth Slag). 



Some time during the summer, section No. 7 was swept clean of 

 ereenings and dust, apparently in preparation for a surface treat- 

 ment. In spite of this, there is no evidence of raveling. The whole 

 -hows wide shallow ruts, with the large pieces of slag pro- 

 truding. On the fill, from 100 to 200 feet from the south end of 

 the section, the west rut is between 2 and 3 inches deep, and the 

 depression over the culvert at the north end of the (ill is a menace to 

 traffic. 



Aboul 50 feet of the south end of the section was given a surface 

 treatment of asphaltic oil during the summer when Price Road was 

 d. The treatment has worn uniformly. 



