4 BULLETIN 105, IT. S. DEPARTMENT OF AGRICULTURE. 
Table 3. — Analyses of native and oil-asphalt products used in the surface treatment of 
concrete. 
Materials. 
Sections 
Specific gravity 25°/25° C 
Melting point ° C 
Penetration (25° C, 100 grams, 5 seconds [mm.]) 
Per cent of loss at 163° C, 5 hours (20 grams) 
Penetration of residue (mm. ) 
Per cent of total bitumen insoluble in 86° B. naphth 
Per cent of fixed carbon 
Per cent soluble in CS2 (total bitumen) 
Per cent of organic matter insoluble 
Per cent of inorganic matter insoluble 
Fluxed native 
asphalt. 
No. 1. 
No. 2. 
Oil asphalt. 
No. 1. 
C,D,and „ 
I. 
No. 2, 
1.045 
39 
18.4 
3.50 
6.3 
19.60 
9.83 
1.043 
48 
14.8 
2.73 
6.4 
21.87 
11.17 
1.031 
92 
12.6 
.32 
1.8 
34.84 
15.62 
1.012 
52 
14.7 
.59 
10.3 
21.72 
10.92 
94.70 
1.23 
4.07 
J6.56 
1.35 
2.09 
J. 74 
.17 
99.72 
.17 
.11 
100.00 
100. 00 I 100. 00 
100.00 
1 Penetration (0° C, 200 grams, 1 minute) 1.4 mm.; penetration (46° C, 50 grams, 5 seconds) 5.8 mm. 
Experiment No. 4. — Oil-cement concrete. 
Location : 
Station 30+90 to station 33+60, gravel aggregate. 
Station 42+50 to station 44+61, limestone aggregate. 
Station 46+10 to station 49+00, trap rock aggregate. 
Total length: 771 feet. 
Total area: 1, 744 square yards. 
Methods and materials. — Owing to irregularity in the delivery of 
the materials, it became necessary to build experiments Nos. 4 and 5 
in separated sections. The first two sections in the order above given, 
were completed in 1912, while the third was built in the spring of 1913. 
The concrete was mixed in a mechanical mixer of the self-propelled 
rotary-distributor type. The proportions were 1 part of Portland 
cement to If parts of sand and 3 parts of coarse aggregate, with 
enough water to produce a concrete of quaky consistency. A light 
residual petroleum having the characteristics given below in Table 
No. 5 was mixed with the concrete to the amount of 5 pints per bag 
of cement. This mixture was accomplished by delaying the intro- 
duction of the oil until after the cement, sand, coarse aggregate, 
and water had been partially mixed. The concrete was spread evenly 
over the subgrade to a depth slightly greater than the finished thick- 
ness of 6 inches and the surface was then " struck off" by means of 
a well-designed "strike board." After this the surface was finished 
to true grade and cross-section with a wooden float. The floating 
was done from a bridge which rested upon the side forms and the 
concrete gutter. Expansion joints were purposely omitted and no 
joints of any other kind were constructed except those between the 
days' work, and these were formed at an angle of 80 degrees to the 
center fine of the road. Before continuing the work of laying the 
