Practice Question: Water Content of a Soil Sample

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Solution

Answer: C) 0.29

Consider the relationship between saturated unit weight and water:

$$ \gamma_{sat}=\frac{\gamma_w\left(SG+e\right)}{1+e} $$

$$ Given\ \gamma_{sat}\ =\ {2\gamma}_w: $$

$$ {2\gamma}_w=\frac{\gamma_w\left(SG+e\right)}{1+e} $$

Solving for the specific gravity, SG:

$$ 2=\frac{\left(G+0.80\right)}{1+0.8};G=2.8 $$

$$ SG\ =\ 2.8 $$

Calculate water content based on its relationship with specific gravity SG and degree of saturation, S:

$$ w=\frac{S\ast e}{SG} $$

$$ where\ S=1.0\ for\ saturated\ samples $$

$$ w=\frac{1.0\ast0.8}{2.8}=0.29 $$
 

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