30 BULLETIN 704, U. S. DEPARTMENT OF AGRICULTURE. 
Size, Grading, or Mechanical Analysis of Broken Stone, Broken Slag, or 
Gravel. (Bulletin 555, page 32 (8).)—A sample of the material weighing not: 
less than fifty (50) times the weight of the largest size stone present is used. 
After drying at not over 110° C. (230° F.) to constant weight, the sample is 
passed through such of the following size screens, having circular openings, 
as are required or called for by the specifications, screens to be used in the 
order named: 33-inch, 38-inch, 23-inch, 2-inch, 13-inch, 1-inch, ?-inch, 3-inch, and 
4-inch. 
The percentage by weight, retained on each screen, is determined and the 
mechanical analysis is recorded in the following manner: 
Per cent. 
Passing 34-inch screen and retained on 3-inch screen : 
7Passine:3-inch screeniand retained: Om: 25-1 SEree ns sees ee ee eee 
iPassine 22-ineh!screen and retained: on)2-inch’ sereene= 2 = a) ee ee 
Passing 34-inch screen and retained on j-inch screen......-- jo are EER re BEE ote ee 
‘Passing s-inch SCCM. 1.5 oe 2 e's Bee se ccs san ae en ea eee 
Elutriation Test of Sand. (Bulletin 555, page 32.)—-The entire sample is 
moistened and thoroughly mixed, and a sample weighing approximately 1057 
grams is obtained for elutriation and grading by quartering or by selecting 
small portions from various parts of a flat pile. The sample is then dried at 
not over 110° C. (230° F.). This dried sample is accurately weighed and placed 
in a 500-ce.2 beaker, and about 350 ec.* of water is added and agitated in such 
manner that no whirling results. After settling for 20 seconds, the water is 
poured off through a 200-mesh sieve, and the operation of agitation, sedimen- 
tation, and decantation repeated until the wash water is approximately clear. 
Particles caught on the 200-mesh sieve are then washed back into the washed 
sample remaining in the beaker. The entire washed sample is dried to con- 
stant weight and accurately weighed, and the 
Original weight — Final weight 
Per cent by: elutriation = >= = Oe 
Original weight 
Mechanical Analysis or Grading of Sand or Fine Aggregate. (Bulletin 
555, page 33.)—All of the dried sample remaining after the elutrition test, if 
such is required, is passed successively through the desired screens and sieves, 
beginning with either the largest or smallest as may be convenient. Where an 
elutriation test is not required, a dried sample of the original material weighing 
about 100 grams is used. 
The percentage, by weight, of the unwashed sample retained on each screen 
is determined, and the mechanical analysis is recorded according to one or 
both of the following methods. A screen with j-inch circular openings is used, 
together with square-mesh sieves as specified in A. S. T. M. Standard Methods 
D7-16. 
Per cent. 
Totalretained on'+-1nchisereen ©... S255 fe -c= eiscicese ease one = See ama ee ak oe eee eee 
Passing +-inchiscreeand retained oni l0-meshisiever. sees nessa ee ae ee 
Passing 10-mesh sieve and retained on 20-mesh sieve....--.....-+..--.s--- ce seceoe ees cnccccnes 
Passing 20-mesh sieve and retained ‘on 30-mesh Si¢ve_...-. 5, - 22 - -- coe e oe eee eee aoe 
Passing 30-mesh sieve and retained on 40-mesh Sieve..........-....---.------------- Seer ae 
Passing 40-mesh sieve and retained on 50-mesh’sieves..---2 5... 25. 8.22220. eee eee eee 
Passing 50-mesh sieve and retained on 80-mesh Sieve........----.--.---------------------e-e-- 
Passing 80-mesh sieve and retained on 100-mesh sieve...........--.--------.---------+------ee 
Passing 100-mesh sieve and retained on 200-mesh Sieve........../.-.------------------+---+--- 
Passing 200-mesh\siGves cc= sas Gee sie Seysamix ot clei bi eee nee eee ee = Se toe cide Se nie Se ee 
TP bade cos Are re ne ee ede recta hy yee ec RAN ee pene (Ae ik Bid et rr 100 
1 Tf the sand is so coarse that a 100-gram sample is not sufficient, the size of the sample, the container, 
and the amount of water used may be proportionately increased. 
