24 BULI^ETIN 691^ U. S. DEPARTMENT OP AGEICULTUEE. 



broken stone to fill the surface voids when thoroughly rolled. 

 A seal coat of the same bituminous material should then be 

 applied at the rate of 0.4 to 0.6 gallon per square yard and covered 

 with a sufficient amount of stone chips to just absorb the excess 

 bitumen. Roads of this character may be maintained with oil 

 surface treatments using the materials and methods given under 

 Specification OC-2 or OH-1. Such maintenance treatments should 

 be applied whenever the wear comes directly upon the wearing 

 course rock. 



