18 
General. 
Physical 
Properties. 
Screenings. 
Coarse Slag. 
Methods of 
Testing. 
BULLETIN 704, U. 8S. DEPARTMENT OF AGRICULTURE. 
placed upon a cement concrete foundation so as to produce, after 
rolling, a wearing course 2 inches in depth. A seal coat of bitu- 
minous material should then bé applied and covered with pea 
gravel in sufficient quantity to take up all excess of bitumen. 
Such roads may be maintained with surface treatments of bitu- 
minous material, covered with -material conforming to Specifica- 
tion RS-2. 
SPECIFICATION SgW 2. 
Slag for Water-Bound Base. 
The broken slag shall consist of angular fragments, reasonably uniform 
in density and quality, free from metallic iron, thin or elongated pieces, 
dirt, or other objecticnable matter. 
The slag.shall meet the following requirements: 
Weight in pounds per cubic foot, each size specified, not less than_ 70 
French COecmelent OF sweat nOtsleSs (6b iia eee 5 
That portion of the product of the crusher, including the dust of 
fracture, which, when tested by means of laboratory sereens, will meet 
the following requirements: 
Per cent. 
Rassine aeinchssereen= notaless; than] ee 95 
ROGal sp aASS in Oy 3 10 CHS CLC ree a a eee 40 to 80 
That portion of the product of the crusher, which, when tested by 
means of laboratory screens, will meet the following requirements: 
Per cent. 
Passing S-ineh SCREeny Ob LESS. terete 95 
POCA PASS 1 Oana GES CTC CR ea D5 ton tS 
Retained on 11-inch sercen: not less: (hen] = eee eee 85 
The tests of the physical properties and sizes of the slag shall be made 
in accordance with the following methods: 
1. Weight per Cubic Foot, U. S. Deparmen of Agriculture Bulletin 
Ms 15y, 10h 24 (Oe 
2. French Coefficient of Wear, U. S. Department of Agriculture Bulletin 
347, p 
3. Grading, U. S. Department of Agriculture Bulletin 555, p. 32 (8). 
This specification provides primarily for slag to be used in the 
construction of a water-bound base upon which some higher type 
of wearing course will be placed, preferably after the base has 
been finally compacted by traffic. For a light traffic road it may 
also serve for both foundation and wearing course, provided the 
thickness of each is not less than 4 inches. 
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