SAMPLING AND TESTING HIGHWAY MATERIALS. 
11 
is 2h inches long. A notch is filed across its lower end, to stop 
the drip from the displaced water. To determine the specific 
gravity and absorption, the dried and cooled sample shall he 
weighed to the nearest 0.5 gram and immersed in water for 24 
hours. The pieces shall then be surface-dried individually with a 
towel, the sample reweighed and immediately placed in the 
cylinder, which has beeo previously filled to overflowing with 
water at room temperature. 
(2) The weight of water displaced by the sample shall be used 
to calculate its apparent specific gravity. The difference between 
the original weight of the sample and its weight after L'4 hours 
shall be used to determine the absorption. 
TEST FOR MECHANICAL ANALYSIS OF AGGREGATES FOR 
CONCRETE. 
(A. S. T. M. standard method, serial designation C 41-22, slightly modified.) 
1. A representative test sample of the aggregate shall be 
selected, by quartering or by use of a sampler, which after dry- 
ing will give not less than the following: 
(a) Fine aggregate. 500 grams. 
( h ) Coarse aggregate or a mixture of fine and coarse aggre- 
gates, weight in grams, 3.000 times size of largest sieve required, 
measured in inche*. 
Table 1. 
Selection of 
sample. 
Sieve 
number 
or size in 
inches. 1 
Sieve opening. 
Wire diameter. 
Inches. 
No. 100.... 
0. 0059 
No. 50 
.0117 
No. 30.... 
. 0232 
No. 16.... 
.0469 ! 
No. 8 
.0937 
No. 4 
.187 
| inch 
finch 
. 375 
.75 
linch 
1.00 
H inches.. 
1.50 
2 inches.. . 
2.00 
3 inches . . . 
3.00 
Mm. 
0.149 
.297 
.59 
1.19 
2.38 
4.76 
9.5 
19.0 
25.4 
38.0 
50.8 
76. 
Inches. 
0.0040 
.0074 
.0130 
.0213 
.0331 
.0.50 
.092 
.135 
.162 
.177 
.192 
.25 
Mm. 
0.102 
.188 
.33 
..54 
.84 
1.27 
2.33 
3.42 
4.12 
4.50 
4.88 
6.3 
Tolerance. 
\vera?e Wire i Maxi " 
A™^™ diam- mum 
opening. eter opemng . 
Percent. Percent. 
ent. 
Per cent 
20 
40 
20 
40 
10 
25 
10 
10 
10 
10 
10 
10 
10 
10 
10 
in 
10 
10 
10 
10 
10 
10 
10 
10 
1 Sieves No. 100 to No. 4 are based on "Table of Fundamental Data on Staiidard 
Specifications for Sieves," isued by the U. S. Bureau of Standards, 1920. The liberal 
tolerances will permit the use of certain sieves which do not exactly correspond to tin- 
numbers given in the table. 
2. The sample shall he dried at nor over 110° C. (230' 
constant weight. 
3. (a) The sieves shall be of square-mesh wire cloth and shall 
be mounted on substantial frames constructed in a manner thai 
will prevent loss of material during sifting. 
(6) The size of wire and sieve openings shall be as given in 
Table 1. 
4. (a) The sample shall be separated into a series of sizes 
by means of the sieves specified in section 3. Sifting shall be 
continued until not more than 1 per cent by weight of the sample 
passes any sieve dnring one minute. 
(b) Each size shall be weighed on a balance or scale which 
is sensitive to one one-thousandth of the weight of the test 
sample. 
(c) The percentage by weight of the total sample which Li 
finer than each of the sieves shall be computed. 
It to Method of test 
