Civil Engineering - Soil Mechanics and Foundation Engineering - Discussion

W1= Wt. of pycnometer = 125 g.

W2 = Wt. of pycnometer + Wt. of dry soil = 500 g.

W3 = Wt. of pycnometer + wt. of dry soil + wt. of water = 850 g.

W4 = Wt. of pycnometer + wt. of water = 500*1 + 125 = 625g,

where density of pure water = 1g/cc, volume of pycnometer = 500 cc.

G = (Wt. of dry soil)/(Wt. of water of equal volume (means equal to the volume of dry soil).

G = (W2-W1)/((W4-W1)-(W3-W2)).

Hence, G = (500-125)/((625-125)-(850-500)).

G = 375/(500-350).

G = 375/150.

G = 2.5.

Weight of soil solids = 500-125 = 375g.
The weight of water when the soil is also present in the pycnometer = 850-500 = 350g.
the Weight of water when water fills pycnometer = 500cc * 1g/cc = 500g (Since the unit weight of water is 1g/cc).
Therefore weight of equal volume of water = 500-350 = 150g.
Specific gravity = (Weight of soil solids)/(Weight of equal volume of water) = 375/150 = 2.5.

S.G. = C/(B-A).

C = Oven dry weight = (500-125) = 375 g.

B = SSD weight = 500 g.

A = A1-A2 = 850-500 = 350 g.

A1 = Weight of dry soil+Water+pycnometer = 850 g.

A2= Weight of water+pycnometer = 500 g.

S.G. = C/(B-A) = 375/(500-350) = 2.5.

Wcs=500g / Wc=125g / Wcsw=850g Wcw = 125+500 = 625g then.

Ws= Wcs-Wc = 500-125= 375g.

Gs = (Ws)/(Ws + Wcw-Wcsw).

=375/(375+625-850).

=375/150 = 2.50 (Ans. C).

SG = Wt of dry soil/Distilled water.

Wt of dry soil = 500 - 125,
Wt of distilled water = 850 - 500,
(no need to find W4, the density of pure water or anything else).

G equs (w2-w1)/(w2-w1)-(w3-w4).

w2 equs500...w1 equs125...w3equs850...w4equs(500plus125)equs 625.

Put value and get an answer.

W1 = 125.
W2 = 500.
W3 = 850.

W4 = 500*1+125 = 625.
Md = 375.

W4 = W3-Md+Md/G.
G = 2.5.

Above formula also replace by:

G = W2-W1/(W2-W1)-(W3-W4).

Above mentioned calculation of Wcw not clear.

@Abhay

Thanks for explanation.