Pycnometer method (water content) machen link

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Method of Determining Water Content

1. Oven Drying Method
2. Sand Bath Method
3. Alcohol Method
https://www.youtube.com/watch?v=KgrKaUgohHw&t=4s
4. Pycnometer
5. Calcium Carbide Method
6. Radiation Method
7. Torsional Method


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https://www.machenlink.com/course/soil-mehcanics/

1. SOIL MECHANICS
Determination of
Water Content
by
Pycnometer
Method

2. For full course visit our website,…
This is the excerptfrom
Lecture 04
of
Soil Mechanics
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3. 4. Pycnometer Method
L. 04 Determination of Water Content
900 ml
6 mm
Procedure :
•Itisaquickmethodinwhichresultisobtainedbetween10to20
minutes.Thismethodisusedforonlythosesoilwhosespecific
gravityisknown.
•Pycnometeris900mlflaskhavingconicalbrasstophaving6mm
diaholeatitscenter.

4. L. 04 Determination of Water Content
•Series of observation to compute water content are as follows:
▪weightofemptypycnometerisobservedinitially(??????
�).
▪200-400gmmoistsample(??????
�)withpycnometer.
▪Emptyvolumeofpycnometerisfilledwithwateralongwithsimultaneousremovalofairpresentin
soileitherbyconstantstirringorbyuseofvacuumatthetopofpycnometer.
▪Pycnometerisbeingagainweightafterfillingtheemptyvolumewithwater(??????
�).
▪Pycnometeristhencompletelyemptiedandagainfilledwithwateraftercleaningproperly(??????
�).
??????
1 ??????
2
Moist soil
??????
3 ??????
4

5. Let’s sayweight of solid in (b)=??????
??????
Weight of moist soil in pycnometer =??????
2−??????
1
weight of water in the moist soil sample ??????
??????
Weight of water ??????
??????
=
??????
??????
??????.??????
??????
=
??????
??????
??????
??????
Volume of solid (??????
??????)
Volume of water equivalent to
volume of solid
=
??????
??????
??????.??????
??????
Weight of Solid ??????
??????
=??????
2−??????
1−??????
??????
??????=
??????
??????
??????
??????
??????
??????=
??????
??????
??????
??????
??????=
??????
??????
??????
??????
×100%
▪Pycnometerisbeingagainweightafterfillingtheemptyvolumewithwater(??????
�).
▪Pycnometeristhencompletelyemptiedandagainfilledwithwateraftercleaningproperly(??????
�).
??????
1 ??????
2
Moist soil
??????
3 ??????
4
L. 04 Determination of Water Content
(a) (b) (c) (d)
??????
??????=
??????
??????
??????

6. ??????
3−??????
4=??????
??????
??????−1
??????
⇒??????
??????=(??????
3−??????
4)
??????
??????−1
??????
??????
??????
??????
??????= ×100 %
(??????
2−??????
1)−??????
??????
??????
??????
×100%=
??????
1 ??????
2
Moist soil
??????
3 ??????
4
(a) (b) (c) (d)
If the solids from (c) are replaced with water of
equivalent weight
We get the weight (??????
4) from (d).
??????
4=??????
3−??????
??????+
??????
??????
??????
??????
4=??????
3−??????
??????1−
1
??????
⇒
=
??????
??????
??????.??????
??????
×??????
??????=
??????
??????
??????
Equivalent weight of water
??????
??????
??????
L. 04 Determination of Water Content

7. ??????
??????
??????
??????
??????= ×100 %
(??????
2−??????
1)−??????
??????
??????
??????
×100%=
??????
3−??????
4=??????
??????
??????−1
??????
⇒??????
??????=(??????
3−??????
4)
??????
??????−1
Let’s sayweight of solid in (b)=??????
??????
Weight of moist soil in pycnometer =??????
2−??????
1
weight of water in the moist soil sample ??????
??????
Weight of water ??????
??????
=
??????
??????
??????.??????
??????
=
??????
??????
??????
??????
Volume of solid (??????
??????)
Volume of water equivalent to
volume of solid
=
??????
??????
??????.??????
??????
Weight of Solid ??????
??????
=??????
2−??????
1−??????
??????
??????=
??????
??????
??????
??????
×100%
??????=
??????
??????
??????
??????
??????
??????=
??????
??????
??????
??????
??????
1 ??????
2
Moist soil
??????
3 ??????
4
(a) (b) (c) (d)
L. 04 Determination of Water Content
If the solids from (c) are replaced with water of
equivalent weight
We get the weight (??????
4) from (d).
??????
4=??????
3−??????
??????+
??????
??????
??????
??????
4=??????
3−??????
??????1−
1
??????
⇒
=
??????
??????
??????.??????
??????
×??????
??????=
??????
??????
??????
Equivalent weight of water
??????
??????
??????
??????=
??????
2−??????
1
??????
3−??????
4
??????−1
??????
−1×100%

8. Inordertodeterminethewatercontent,370gofawetsandysamplewasplacedinapycnometer.Theweightof
thepycnometer,sandandwaterfulltothetopoftheconicalcapwasfoundtobe2148g.Theweightof
pycnometerfullofcleanwaterwas1932g.
TakingG=2.65,determinethewatercontentofthesample.
04.
Example 04 (Water content of moist soil sample using Pycnometer )L. 04
Strategy:
Solution:
??????=
??????
2−??????
1
(??????
3−??????
4)
×
??????−1
??????
−1×100
Step 1:
Weight of soil sample is already given separately. Use the formula of water content
Write the given data
Weight of soil sample= ??????
2−??????
1
= 370 gm
Weight of pycnometer, sand and water (??????
3) = 2148 gm
Weight of pycnometer and water (??????
4) = 1932 gm

9. Solution:
??????=
??????
2−??????
1
(??????
3−??????
4)
×
??????−1
??????
−1×100
Step 1:Write the given data
Weight of soil sample= ??????
2−??????
1
= 370 gm
Weight of pycnometer, sand and water (??????
3) = 2148 gm
Weight of pycnometer and water (??????
4) = 1932 gm
Example 04 (Water content of moist soil sample using Pycnometer )L. 04
??????=
370
2148−1932
×
2.65−1
2.65
−1×100
w=6.5%