General. 
Size. 
Method of 
Testing. 
General. 
Physical 
Properties. 
Screenings. 
Chips, 
Top Course 
Stone. 
BULLETIN 704, U. S. DEPARTMENT OF AGRICULTURE. 
SPECIFICATION RS—2. 
Fine Broken Stone or Gravel for Bituminous Surface Treatment. 
The broken stone or gravel shall consist of clean hard tough durable 
stone, free from soft or disintegrated particles, dirt, or other objectionable 
matter. 
When tested by means of laboratory screens it shall meet the following 
requirements : 
Per cent. 
IP ASSIN Ss -1N CHS Ch CCT, 5100 G SLOSS GE 201 eo cere 85 
Retained cons s-1N CH) SCLCCM OL OSS 01a eee eee 85 
Tests of the size of broken stone or gravel shall be made in accord- 
ance with the following method: 
Size, U. S. Department of Agriculture Bulletin 555, p. 32. 
This specification provides for a product to be used as cover for 
a bituminous material applied to a road surface. For this pur- 
pose 1 cubic yard should cover from 50 to 150 square yards of 
treated road surface, depending upon the amount of bituminous 
material which has been applied per square yard. Under traffic 
it is expected to produce, in combination with the bituminous ma- 
terial, a thin wearing mat or carpet. It may be considered as an 
alternate for Specification RS-—1 and preferable to the latter when 
the treatment of bituminous material is less than 4 gallon per 
square yard. 
SPECIFICATION RB-1. 
Broken Stone for Bituminous Macadam. 
The broken stone shall consist of angular fragments of rock, excluding 
granite, gneiss, sandstone, quartzite, schist, shale, and slate, of uniform 
quality throughout, free from thin or elongated pieces, soft or disinte- 
grated stone, dirt, or other objectionable matter, occurring either free or 
as a coating on the stone. : 
The stone shall meet the following requirements: 
Hrenchcoehicient of wear, notsless) than==32 2 ee 
oe | 
That portion of the product of the crusher, including the dust of 
fracture, which, when tested by means of laboratory screens, will meet 
the following requirements: 
Per cent. 
IPASSIN' Sim Chy | SELECT aT) Ol LESS i tel a ee G95 
Total passing 4-inch “screeni=! 22.) a 2a eee 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. 
eassine tl -inch)(sereen-\not less) thane See eee 95 
Retainedon: 4-inch yscreens not) less) ‘than! =- 323 = = eee 85 
That portion of the product of the crusher which, when tested by 
means of laboratory screens, will meet the following requirements : 
Per cent. 
Passinesy2-inch! screen, nob) less than ee eee 95 
Total passing 14-inch screen_.___— i OR Ain ee eS 5) ioe AS 
Retained ion d-inchY Screensenot Less ule ee 85 
