28 DEPARTMENT BULLETIN 1216, U. S. DEPT. OF AGRICULTURE 
way materials (serial designation D 55) of the American Society for Testing 
Materials (see p. 22) (//). 
:;. The quantity 02.355 is the weight in pounds of 1 cubic foot of water at 
the standard temperature of 16.7° C. (62° F.). 
-I. The symbol " wt." represents the weight in pounds per cubic foot of the 
fine aggregate as determined by the standard method of test for unit weight 
of aggregate for concrete (serial designation C 29, see p. 27) of the American 
Society for Testing Materials ()). 
21. METHOD OF TEST FOR ORGANIC IMPURITIES IN 
SANDS FOR CONCRETE 
(A. S. T. M. standard method (.}), sevi.il designation C 40—27. except as indicated. 
See p. 1) 
1. This method of test is an approximate method of determining the presence 
of injurious organic compounds in natural sands which are to be used in 
cement mortar or concrete. The principal value of the test is to furnish a 
warning that further tests of the sands are necessary before they are approved 
for use. 
2. A representative test sample of sand weighing about 1 pound shall be 
obtained by quartering or by the use of a sampler. 
3. (a) A 12-ounce graduated clear glass bottle shall be filled to the 4 1 / A-ounce 
mark with the sand to be tested. 
(&) A3 per cent solution of sodium hydroxide in water shall be added until 
the volume of the sand and liquid indicated after shaking is 7 liquid ounces. 
(c) The bottle shall be stoppered, shaken vigorously, and then allowed to 
stand for 24 hours. 
4. A standard color solution shall be prepared by adding 2.5 cubic centimeters 
of a 2 per cent solution of tannic acid in 10 per cent alcohol to 97.5 cubic centi- 
meters of a 3 per cent sodium hydroxide solution. This shall be placed in a 
12-ounce bottle, stoppered, shaken vigorously, and allowed to stand for 24 
hours. 
5. (a) After standing 24 hours, the color of the clear liquid above the sand 
shall be compared with the color of the standard color solution prepared at the 
same time and in accordance with the method described in section 4, or with 
a glass of color similar to the color of the standard solution. 
(b) Solutions darker in color than the standard color have a "color value" 
higher than 250 parts per million in terms of tannic acid. 
6. In lieu of the method, given in paragraph 5 (a) above, the color of the clear 
liquid above the sand may be compared with the colors given in Plate 2. 
Note. — Where chemically pun sodfum hydroxide is not available, ordinarily mailable 
commercial soda lye may be used. 
22. METHODS OF MAKING COMPRESSION TESTS OF 
CONCRETE 
(A. S. T. M. standard methods (.}), serial designation C 39-27) 
1. These methods are intended to cover compression tests of concrete made 
in a laboratory where accurate control of quantities of materials and test con- 
ditions is possible. They are designed to apply primarily to hand-mixed concrete 
compression specimens, but may be used with slight modification in making 
tests of concrete for wearing resistance, bond between concrete and steel, im- 
permeability, etc. The investigation of machine-mixed concrete will require 
certain obvious changes in the methods. For methods of conducting compres- 
sion tests of concrete specimens made during the progress of construction work, 
see the standard method of making and storing specimens of concrete in the 
field (serial designation C 31, see p. 31) of the American Society for Testing 
Materials < J i. 
2. Materials shall be brought to room . temperature (18° to 24° C, 65° to 
75° F. ) before beginning the tests. Cement shall be stored in a dry place, 
preferably in covered metal cans. The cement shall be thoroughly mixed in 
advance in order that the sample may be uniform throughout the tests. It 
