2 BULLETIN 105, U. S. DEPABTMEET OF AGBICVLTUBE. 



Experiment Xo. 3. — Cement coxcrete axd oil-cehext coxcrete (surfaces 



TREATED "WITH BITUMIXOUS MATERIALS). 



Location : 



Cement concrete — 



Station 12+50 to station 15+84, gravel aggregate. 

 Station 15+84 to station 21+60, limestone aggregate. 

 Station 21+60 to station 25+03, gravel aggregate. 

 Oil-cement concrete — 



Station 25+03 to station 27+29, limestone aggregate. 

 Station 27+29 to station 30+90, limestone aggregate. 

 Total length: 



Cement concrete section — 1,253 feet. 

 Oil-cement concrete section — 587 feet. 

 Total area: 



Cement concrete section — 2,837 square yards. 

 Oil-cement concrete section — 1,341 square yards. 



The details regarding the construction of both types of concrete 

 are fully described in Circular Xo. 99, and repeated in this report 

 under experiments Nos. 4 and 5. 



As noted in Circular No. 99, the concrete for these experiments 

 was completed in the fall of 1912, but owing to cold weather it was 

 necessary to postpone the application of surface treatments until 

 1913. The surface of the concrete was then washed, thoroughly 

 swept, and allowed to dry off, after which a number of bituminous 

 materials, singly and in combination, was applied. Where a paint 

 coat is indicated, it signifies a thin surface application of a material 

 for the purpose of possibly securing better adhesion than might 

 otherwise be obtained for the wearing or carpet coat. The paint 

 coats were broomed over the surface without heating. The heavier 

 products were heated in three-barrel kettles, and spread over the sur- 

 face by means of a hand-drawn distributor of about 30 gallons 

 capacity, so designed as to permit the material to flow out in a thin 

 sheet about 18 inches wide. 



The applications were then covered with pea gravel or limestone 

 grits applied by a spreading machine and the road was immedi- 

 ately opened to traffic. 



The locations selected for the various sections are indicated by 

 lettered markers along the roadside. The following is a tabular 

 description of these sections : 



