METHODS OF SAMPLING A.\D TESTING HIGHWAY MATERIALS 25 
5. The approximate apparent specific gravity of the fine aggregate may be 
calculated from the formula : 
5<JO 
Approximate apparent speeifiy gravity ~ - v „_ ■ where F=the combined volume 
in cubic centimeters of the water and fine aggregate in the flask. 
6. Duplicate determinations- should check to within 0.05. Variations in the 
amount of water evaporated from the moist sample as described in section 3 
beyond the point at which the surface moisture has disappeared and the sample 
is free flowing and apparently dry will cause variations in results of from 0.5 
to 1 per cent depending upon the absorption of the aggregate. 
17. METHOD OF TEST FOR FIELD DETERMINATION OF 
APPROXIMATE PERCENTAGE OF VOIDS IN FINE 
AGGREGATE 
(A. S. T. M. tn.tativ standard method (5), serial designation C 69-27 T) 
1. This method of test is intended for use in the field for making approximate 
determinations of the percentage of voids 
in fine aggregate when inundated with 
water. 
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 
or less. 
( h ) Flask. — A special graduated flask of 
the type and conforming to the dimensions 
shown in Figure 8. 
3. A sample weighing about 2 kilograms 
shad be selected which shall be as truly 
representative of the fine aggregate as 
ble. It shall be well mixed and 
spread out on a flat surface and air dried 
until the surface moisture has evaporated 
and the sample is free flowing. 
4. About 100 cubic centimeters of water 
shall be placed in the flask. Aggregate 
fpom the room-dry sample shall then be 
introduced ^lowly into the flask until the; 
flask is filled to the 40O-cubic centimeter 
mark on the upper neck. Water shall be 
added as required to keep the aggregate 
inundated as the filling pi When 
the flask is filled to the 400-cubic centimeter 
mark, both water and aggregate shall be 
at the same level. The aggregate in the 
fla^k shall not be agitated during or after 
the filling operation. The flask and con- 
tents shall be weighed to the nearest 
gram, and the weight of the flask shall 
l>e deducted, unless its weight ha< been 
counterbalanced on the scale at tbe time 
< i weighing. 
5. {a) Thi- method requires that The 
apparent specific gravity be known of the 
fine aggregate in a room-dry, free-flowing 
condition, but with the voids within the 
particles of the aggregate containing mois- 
ture If the apparent specific gravity of 
the aggregate in this condition is not known, it shall be determined in accord- 
ance with the tentative method of test for field determination of approximate 
apparent specific gravity of fine aggregate (serial designation C 68-27 T) of the 
-American Society for Testing Materials (5). 
Volume of lower cham- 
ber to mark on lower 
neck = 200 cc. 
Combined volume o * 
er and upper chambers 
to lower end of gradu- 
ated scale on. upper neck 
=375cc. 
Scale graduated in kc. 
divisions from 375 cc. 
to 450 cc. 
-rferof opening in 
lower neck, approximate- 
fyi"- 
Diameierofbore cfgradu- t 
ated upper neck, approxi- 
mately ^". 
Range of use: From dry 
sand of2.8sp. gr. to sand 
of 2. 2 sp. gr:, having 10 
percent moisture. 
Fig. 8. — Graduated flask for field tear- 
ing of fine aggi 
