38 DEPARTMENT BULLETIN 1216, U. S. DEPT. OF AGRICULTURE 
4. The percentages in mechanical analysis shall be reported in the following 
manner : 
Per cent 
Passing the No. 200 sieve 
Passing the No. 100 sieve and retained on the No. 200 sieve 
Passing the No. 80 sieve and retained on the No. 100 sieve 
Passing the No. 50 sieve and retained on the No. 80 sieve 
100. 00 
29. METHOD OF MECHANICAL ANALYSIS OF COARSE 
AGGREGATES 20 
(A. S. T. M. standard method (4), serial designation D 18-16 except as indicated. See 
p. 1) 
The method shall consist of (1) drying at not over 110° C. (230° F.) to a 
constant weight a sample weighing in pounds six times the diameter in inches 
of the largest holes required : (2) passing the sample through such of the follow- 
ing size screens having circular openings as are required or called for by the 
specifications, screens to be used in the order named: 8.89 centimeters (3 x /2 
inches), 7.62 centimeters (3 inches), 6.35 centimeters, (2% inches), 5.08 
centimeters (2 inches). 3.81 centimeters (1% inches), 3.18 centimeters (1*4 
inches). 2.54 centimeters (1 inch). 1.90 centimeters (% inch), 1.27 centimeter 
(% inch), and 0.64 centimeter (% inch) ; (3) determining the percentage by 
weight retained on each screen ; and (4) recording the mechanical analysis in 
the following manner. 21 
Per cent 
Passing 0.64-centimeter (14-inch) screen 
Passing 1. 27-centimeter (%-inch) screen and retained on a 0.64- 
centimeter (14-inch) screen 
Passing 1.90-centimeter (%-inch) screen and retained on a 1.27- 
centimeter (%-inch) screen 
Passing 2.54-centimeter (1-inch) screen and retained on a 1.90- 
centimeter (%-inch) screen 
100. 00 
30. METHOD OF MECHANICAL ANALYSIS OF EXTRACTED 
AGGREGATES 
1. The mineral aggregate left after extraction of the bituminous material 
shall be dried at not over 110° C. (230° F.) to a constant weight. It shall' be 
separated by the use of a screen having openings one-quarter inch in diameter. 
The portion retained on the screen shall be examined in accordance with the 
method for mechanical analysis of broken stone, etc. The portion passing this 
screen shall be examined in accordance with the method for the mechanical 
analysis of sand or other fine aggregate, except that the percentage of 200-mesh 
material shall be determined as follows : A 10-mesh sieve shall be superim- 
posed on a 200-mesh sieve and the aggregate placed on the 10-mesh sieve. The 
material is then immersed and gently oscillated in a bath of gasoline until all 
fine material has been washed off. The washed material is then dried and 
weighed. The weight of material passing the 200-mesh sieve may be obtained as 
follows : 
Weight of total mineral aggregate (including weight of mineral material 
recovered from extract) minus weight of material retained on sieve gives 
weight of mineral matter passing 200-mesh sieve. 
20 This method is intended primarily for use in conneetion with the mechanical anahjsis 
of coarse aggregates for various types of road construction, including concrete, when "he 
sizes are specified on the basis of round hole screens. 
21 Attention is called to the fact that the 1-inch screen is not necessarily the largest 
screen which may be used. 
