Question $2(12$ marks$)$

A sample of dry sand having a unit weight of $18\mathrm{.}2k\frac{N}{m^3}$ and a solids specific gravity of $2\mathrm{.}72$ is

placed in the rain. During the rain, the volume of the sample remains constant and no solid particles

are lost. However, the degree of saturation increases to $50\%.$ Determine:

a$.$ The change in void ratio caused by the rain.

b$.$ The void ratio $($e$)$ after the rain.

c$.$ The total unit weight $({}_1)$ after the rain.

d$.$ The water content $(w)$ after the rain.

Question $3(12$ marks$)$

Consider the soil whose PSD curve is shown in Figure $1$ below. The soil has PL $=20\%$ and $LL=$

$60\%.$ Answer the questions below. You may refer to the attached USCS table where necessary.

a$.$ What is the fines content of the soil?

b$.$ According to the USCS, is the soil coarse$-$grained or fine$-$grained?

c$.$ What is the plasticity index of the soil?

d$.$ Calculate $D_{60},D_{10},$ and $D_{10}.$

e$.$ Compute the coefficient of uniformity $(C_4)$ and the coefficient of curvature marks$]$

f$.$ In the plasticity chart, do the Atterberg limits of this soil plot above or below the A$-$line?

Justify your answer.

$[2$ marks$]$

g$.$ Classify the soil according to the USCS. Clearly explain each step of the classification process

until you arrive at the group symbol$($s$).$