SAMPLING AND TESTING HIGHWAY MATERIALS. 
car or boat during unloading. It is recommended that separate 
samples be taken from tbe top, middle, and bottom of car or boat. 
These separate materials shall be well mixed in a composite 
sample and the sample for test obtained by the quartering method. 
C. Quantity of Sand and Gravel Samples. 
19. Samples of run-of-bank (material in which the sand and Size of 
gravel are combined) shall consist of at least 100 pounds of ma- samples. 
terial when the gravel content is 50 per cent or more of the whole. 
If the material contains less than 50 per cent of gravel, the sample 
shall be increased in proportion. For example, when the gravel 
percentage is 25 per cent of the whole the sample should weigh 200 
pounds. 
20. Samples of sand shall contain at least 20 pounds of material. 
21. Samples of gravel shall contain at least 50 pounds of ma- 
terial. 
22. The quantity of samples to b*e tested for concrete aggregate 
will depend upon the kind of tests to be made and the number of 
specimens necessary. 
IV. SAMPLING OF MISCELLANEOUS MATERIALS. 
23. Samples of slag sand, screenings, mine tailings, and all other 
materials used as substitute for sand and gravel or broken stone, 
shall be inspected and sampled in the same way as the materials 
for which they are substituted. 
V. SAMPLING OF STONE BLOCK. 
24. Samples shall be taken either at the quarry or from cars or 
boats as directed by the engineer. They shall be representative 
of the block which it is proposed to use and no sample shall in- 
clude block that would be rejected by visual examination. 
25. The sample shall consist of at least six blocks and the bed- 
ding plane shall be marked on at least two of these. 
VI. SAMPLING OF PAVING BRICK. 
26. Place of sampling. — Where a standard rattler has been in- Place of 
stalled and is kept in an approved condition, and acceptable sampling. 
facilities for testing are furnished by the manufacturer, samples 
will be taken and tested at the plant by an inspector while 
cars are being loaded, provided daily shipments are sufficient to 
warrant it. Under all other conditions samples will be taken 
from the cars upon arrival at their destination. 
27. Method of selecting samples. — A single sample will be taken Method of 
to represent each 10,000 to 15.000 brick according to conditions sampling. 
described later. No brick are to be included in the sample which 
are cracked or so deformed as to be unfit for laying under the 
specifications. 
28. (a) Samples from kilns. — When samples are taken directly Samples 
from the kiln, the first set will usually be chosen as soon as from kilns. 
enough brick have been removed from the front of the kiln 
to permit of obtaining a sample representative of both the full 
width and height of the kiln. Later samples are to be taken 
with the idea of representing three degrees of burning in the kiln, 
one sample to be selected from localities (usually the top and 
sides) to represent the hardest burned brick, one sample usually 
selected from the more central portion of any cross section of 
the kiln to represent medium burned brick, and one sample usually 
from the bottom layers and away from the sides to represent 
the least burned brick. Each of these samples should represent 
approximately 15.000 brick. 
(b) Samples taken from piles. — When the appearance of the Samples 
pile of brick shows clearly that there is a considerable range in from piles. 
the degree of burning, samples to represent each of three degrees 
