TESTS FOR NON-BITUMINOUS 
ROAD MATERIALS. 
1. ABRASION TEST FOR BROKEN 
STONE. 
(A. S. T. M. Standard method, serial designation 
D 2-08, slightly modified.) 
(1) The machine (see fig. 1) shall consist 
of one or more hollow iron cylinders, closed 
at one end and furnished with a tightly fit- 
ting iron cover at the other; the cylinders to 
be 20 cm. in diameter and 34 cm. in depth 
inside. These cylinders are to be mounted 
on a shaft at an angle of 30° with the axis of 
rotation of the shaft. 
(2) The rock to be tested shall be broken 
from large irregular pieces to as nearly uni- 
form size as possible, and as near to 50 pieces 
as possible shall constitute a test sample. No 
pieces having edges or faces that have been 
rounded by wear shall be included. The 
total weight of rock in a test shall be within 
10 grams of 5 kilograms. All test pieces 
shall be washed and thoroughly dried before 
weighing. Ten thousand revolutions, at the 
rate of between 30 and 33 per minute, shall 
constitute a test. Only the percentage of 
material worn off which will pass through a 
0.16-cm. (-^-inch) mesh sieve shall be con- 
sidered in determining the amount of wear. 
This shall be expressed as the percentage of 
the 5 kilograms used in the test. 
(3) For materials having a specific gravity 
below 2.20 the quantity used for the test 
shall be adjusted on a volume basis, re- 
taining the specified number and size of 
pieces. For such materials a volume of 
4,000 c. c. of the broken stone or broken slag 
shall be used. 
2. ABRASION TEST FOR GRAVEL. 
(1) The aggregate shall first be screened 
through screens having circular openings 2 
inches, 1| inches, 1 inch, f inch, and \ 
inch in diameter. The material of these 
sizes shall be washed and dried. The fol- 
lowing weights of the dried stone shall then 
be taken: 1,250 grams of the size passing the 
2-inch and retained on the l-|-inch screen, 
1,250 grams of the size passing the 1^-inch 
and retained on the 1-inch screen, 1,250 
grams passing the 1-inch screen and retained 
on the f-inch screen, 1.250 grams passing 
