Q1: A sample of saturated soil has 30% water content and the specific gravity of soil grains is 2.6. The dry density of the soil mass in g/cm³, is

ANS:A - 1.47

For saturated soil,
Yd=(G+e)Yw/(1+e),
Yd=(2.6+.78)1/(1+.78),
Yd= 1.91. We have Yd=GYw/(1+e).

We have to calculate the value of e from S.e=W.G.
S=1, W=0.3,G=2.6 all values put and find e as 0.78.

Now all putting in eq.Yd = GYw/(1+e).
Yd = 2.6/(1+0.78).
Yd = 1.46. Sr.E = W.G.

Saturated soil, Sr = 1.

Water content, w = 30% = 0.3.

Specific gravity, G = 2.6.

Using formula, e = 0.78.

Now, Yd = (G.Yw)/(1 + e).

Solving this, we get dry density, Yd = (2.6X1)/(1+0.78).

= 1.46 gm/cc.