24 BULLETIN 691, U. S. DEPARTMENT OF AGRICULTURE. 
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. 
