SAMPLING AXD TESTING HIGHWAY MATERIALS. 
shall be well mixed to form a composite sample and the sample 
for testing shall be obtained by tbe quartering method 
7. (a) If it is not practicable to visit the plant, samples for 
both quality and size shall be taken from different parts of the 
car or boat during unloading. It is recommended that separate 
samples be taken from the top, middle, and bottom of the car 
or boat. These separate samples shall be well mixed to form 
a composite sample and the sample for testing shall be obtained 
by the quartering method. The results of tests of crushed stone 
for quality are not considered comparable with results from 
samples specially broken for test in the laboratory, but the gen- 
eral quality of the stone can be ascertained and check tests on 
various shipments should indicate any change in quality. In 
this case, tests for both quality and size can be made on the 
same sample. 
( h) If the stone is to be tested for size only, it is recommended 
that a small set of screens and a pair of scales or some recep- 
tacle for measuring volume be used for field testing in order to 
avoid delaying the decision on the use of the material. Occa- 
sional check tests can be obtained from the laboratory to assure 
a fair degree of accuracy in the field testing. 
8. (a) The sample of crushed stone for mechanical analysis 
shall weigh at least 50 times the weight of the largest piece 
therein. 
( b ) The character of samples to be tested for concrete aggre- 
gate will depend upon the kind of tests to be made and the 
number of specimens necessary. 
Weight of 
sample. 
C. Sampling of Field Stone and Bowlders. 
9. A detailed inspection of the deposits of field stone and 
bowlders shall be made in the area from which the supply is to 
be obtained. The different kinds of stone and their state of 
preservation in the various deposits shall be recorded. 
10. Separate samples shall be taken of all stone of different 
classes which, as determined by visual examination of their 
state of preservation and degree of lamination, should be con- 
sidered for use in construction. 
11. Records accompanying samples of field stone and bowlders, 
in addition to general information, shall include the following 
information : 
(a) Location of supply. 
Note. — Thp plotting of the field stonp and bowlder area on a 
United Statps topographic or a similar map is recommpuripd for this 
purpose. 
(b) Approximate quantity available. 
Note. — A fairly accurate pstiraafp of thp amount of stone in 
fences ran 1>p made by measuring a cross sprtion and paring the 
length. It is more difficult to psrimato the amount of stone scat- 
tered on the ground, and ordinarily it does not pay to work such 
deposits unless thp accumulation is heavy. 
(c) Information in regard to the relative amounts of the dif- 
ferent classes of stone sampled and the materials rejected by 
visual examination which have to be handled and spoiled. 
Note. — The pprcpntages of different kinds of material can only 
hp estimated and thp degree of accuracy attainpd will doppnd al- 
most entirely upon the pxpprienep and skill of thp individual. 
II. SAMPLING OF BLAST-FURNACE SLAG. 
12. It is recommended that blast-furnace slag be sampled for 
size and quality by the method specified for broken stone. 
III. SAMPLING OF SAND AND GRAVEL. 
A. Sampling of NONCOMMERCIAL Deposits. 
13. Noncommercial as used here includes all undeveloped sand 
and gravel deposits and all developed deposits where the material 
is not washed or screened. 
Method of 
sampling. 
Information 
with samples. 
