SAMPLING AND TESTING HIGHWAY MATERIALS. 63 
ably divided into three portions for sieving, the sieving being completed over a sheet 
of white paper, and is continued until practically no dust passes the sieve when 
shaking for one minute. The portion retained on the 100-mesh sieve is weighed. 
Five hundred grams minus the weight of the samples retained on the 100-mesh after 
abrasion is taken as the loss from abrasion. This weight divided by 5 gives the per- 
centage of wear. 
44. PROPOSED FIELD METHODS OF MAKING SIEVE ANALYSIS. 
Either volumetric or gravimetric methods may be used on a sample of not less than 
500 grams in the volumetric or 200 grams in the gravimetric test. The following 
methods for making these tests are suggested : 
A. VOLUMETRIC METHOD. 
Briefly described, the apparatus for this test consists of an outside cylindrical con- 
tainer with telescopic cover, two nests of semicylindrical screens and sieves fitting 
into the outside cylinder and containing a smaller cylinder with telescopic cover. 
This small cylinder contains in turn a 10-inch rule having ^-inch divisions and a 200 
c. c. graduated cylinder. The entire outfit is very compact, measuring about 14 
inches in length and 5 inches in diameter. 
Both the outer and inner cylinders are exactly 10 inches in inside depth, the tele- 
scopic covers being made to fit the contents of each cylinder. - As used at present, 
there are in each outfit five screens having circular openings lj-inch, 1-inch, f-inch, 
J-inch, and J-inch in diameter, respectively, and three sieves of standard 10-mesh, 
20-mesh, and 50-mesh, respectively; also three rings of 3-inch, 2^-inch, and 2-inch 
diameter, respectively, fitting in the cover of the container. 
The large cylinder is used when making a screen analysis of a coarse aggregate, 
while the small cylinder is used in determining the gradation of sand or other fine 
aggregate. The cylinder is filled with the material to be examined, which is then 
screened through the screen, or sieve, selected. The portion passing the screen, or 
sieve, is returned to the cylinder and the height of the material determined, each 0.1 
inch corresponding to 1 per cent of the original volume. The portion retained on the 
screen, or sieve, is determined in the same manner. The percentage passing plus 
the percentage retained when obtained in this manner add up to more than 100 per 
cent of the original volume, and if the true percentage passing each screen or sieve is 
to be reported, the correct value is obtained by dividing the percentage passing each 
screen or sieve as found above by the total of the measurements obtained for material 
retained and material passing the screen or sieve. For example, if a gravel shows by 
measurement 60 per cent retained on a 1-inch screen and 50 per cent passing a 1-inch 
screen, the true percentage passing the 1-inch screen is — 
50 50 |K1 
60+50 = no =45i per cent 
B. GRAVIMETRIC METHOD. 
The apparatus required consists of a spring balance, 200-grams capacity, graduated 
to tenth-gram divisions and provided with a weighing pan; a series of field sieves 
well graded in size from a ^-inch screen to a standard 200-mesh sieve. The sample, 
selected in accordance with the method described, shall be dried in the air or by heat- 
ing to not over 110° C. The sample for sieve analysis shall be selected from the dried 
sample by the method of quartering and shall weigh approximately 200 grams. This 
sample shall be passed successively through the various screens required and the total 
percentage passing each sieve shall be reported. 
