2 BULLETIN 105, TJ. S. DEPARTMENT OF AGRICTJLTUKE. 
Experiment Xo. 3. — Cemext concrete and oil-cemext coxcrete (surfaces 
treated "with bituminous 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 Kos. 4 and 5. 
As noted in Circular Xo. 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 : 
