24 DEPARTMENT BULLETIN 1216, U. S. DEPT. OF AGRICULTURE 
(b) Fine material. — The apparent specific gravity of fine material shall be 
determined in the same way as for coarse material except that the sample 
shall consist of air-dried material and shall consist of 1,000 grams. 
ABSORPTION OR FREE WATER CONTENT 
4. The absorption or the free water content of material shall be determined 
upon a sample consisting of material in the condition in which it is to be used. 
5. Two thousand .mams of the sample shall be weighed out to the nearest 
0.5 gram. This sample shall be placed in the pycnometer and the pycnometer 
partly filled with water at 70° F. The pycnometer shall be gently shaken and 
rolled to remove entrained air. The pycnometer shall then be exactly filled 
with water and its outside surface dried. The pycnometer and its contents 
shall then we weighed to the nearest 0.5 gram. 
6. The absorption or the free moisture content of the sample shall be com- 
puted from the following formula: 
Percentage of moisture or absorption l4 = ~—-(W— Wi) - 
S v J/ (? s -l 
Where £f=the weight of the sample in grams, 
P=the weight in grams of the pycnometer filled with water, 
IFi==the weight of the pycnometer containing the sample and sufficient 
water to fill the remaining space. 
(? s =the specific gravity of the saturated surface dry material. 
7. A pycnometer that has been used successfully by the Iowa Highway Com- 
mission consists of an ordinary glass Mason fruit jar with a special cap. This 
cap is the frustrum of a cone superimposed upon a ring which will screw upon 
the top of the jar. This cap may be made from the screw ring from a Kerr 
fruit-jar cap to which is soldered a tin cone with a slope of 60° and a three- 
eighths-inch hole at the top. A more satisfactory cap could be cast from brass 
or some other metal that does not corrode. In using a pycnometer of this 
kind the cap and the jar should be marked so that the cap will be screwed on 
to the same position each time so that the volume of the apparatus will not 
be varied. 
16. METHOD OF TEST FOR FIELD DETERMINATION OF AP- 
PROXIMATE APPARENT SPECIFIC GRAVITY OF FINE 
AGGREGATE 
(A. S. T. M. tentative standard rnethou, (5) serial designation C 68-27 T) 
1. This method of test is intended for use in the field for making approxi- 
mate determinations of the apparent specific gravity of fine aggregate. 
2. The apparatus shall consist of the following : 
(a) Balance. — A balance, preferably of the torsion type, having a capacity of 
2 kilograms or more and sensitive to 0.5 gram or less. 
(h) Flask. — A special graduated flask of the type, and conforming to the 
dimensions, shown in Figure 8. 
3. A 1-kilogram sample shall be selected which shall be as truly representa- 
tive of the fine aggregate as possible. It shall be spread out on a flat surface 
and air dried until the surface moisture has evaporated and the sample is free 
flowing. The sample shall then be thoroughly mixed and 500 grams accurately 
weighed out. 
4. The graduated flask shall be filled to the 200-cubic centimeter mark on the 
lower neck with water at room temperature. The 500-gram sample of fine 
aggregate shall then be slowly poured into the flask, and the flask and con- 
tents agitated while introducing the aggregate to free any entrained air bubbles. 
'Hie combined volume in cubic centimeters of the water and fine aggregate 
shall be read on the scale on the upper neck of the flask. 
14 If the algebraic sign of the result is positive, the material contains free water. If 
the sign is negative, the material absorbs water. 
