The Zero Air Voids: The Zero Air Voids Line

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Moisture Content
Moisture content = Weight of water / Weight of dry sample or w = [(W_(tin+soil )- W_(tin+dry soil))/(W_(tin+dry soil) - W_tin )] x 100 7.1 Average moisture content of specimen, w w = (wt + wm + wb)/3 7.2 The dry unit weight of the specimen can be calculated as follows: Let weight of empty mold = W Weight of mold and compacted soil = W1 Volume of mold, V = 1/30 ft3 (1000cc) Water content of compacted soil = w Moist Unit weight of compacted soil = W1- W =  7.3 V Dry unit weight or dry density, d = …show more content…

The coordinates of the peak of the curve give the maximum dry density and the optimum moisture content.

(c) Determine the optimum water content and maximum dry unit weight of the soil from the curve (γd(max) and wopt).

7.5 The Zero Air Voids Line
The zero air voids (ZAV) line is the combination of moisture and density that produce complete saturation of the soil or the γd obtained when there is no air in the void spaces. The compaction curve theoretically does not cross this line but becomes parallel to it. Remember that the values of water content, wet unit weight, and specific gravity are not constant throughout the soil. There could also be variability in the test results. Variability can result in points on the compaction curve above the ZAV line (S > 100%). These data points should not be thrown out.

Basic weight volume relationships are used to develop the equation for the ZAV line. Recall that:

7.6
Since S = 1 when the saturation is equal to 100 percent, the relationship: Gsw=e can be substituted into the above equation (7.6) to yield the final equation for the ZAV line: …show more content…

Observations

Data and observation sheet for Compaction Test

Performed for __________________ Location __________________________ Project ________________________ Job No. ___________________________ Boring No. ______________ Sample No. _____________ Depth _________ Description of soil _________________________________________________________ Performed by __________________________ Date of Test ________________________
Test Performed in accordance with ________________________________________

a. Cylinder diameter = 10.2 cm b. Height of cylinder = 11.6 cm
c. Height of rammer fall = 30 cm d. Volume of cylinder = 944 cc
e. Weight of cylinder = W gm

Density Determination No. 1 2 3 4 5
Dry Unit Weight Determination
Weight of cylinder/ mold empty, gm
Weight of cylinder + compacted soil
Weight of compacted soil (gm)
Average moisture content (percent)
Wet density(gm /cc)
Dry density

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