What is relative density (D.)? Please write the definition expression and write some standards to measure the degree of compaction of coarse-grained soils by relative density (D.)
Answers
Answer:
1. Objective
Porosity of a soil depends on the shape of grain, uniformity of grain size and condition of sedimentation. Hence porosity itself does not indicate whether a soil is in loose or dense state. This information can only be obtained by comparing the porosity or void ratio of the given soil with that of the same soil in its loosest and densest possible state and hence the term, relative density is introduced.
Relative density is the measure of compactness of cohesionless soil. Relative density or density index is the ratio of the difference between the void ratios of a cohesionless soil in its loosest state and existing natural state to the difference between its void ratio in the loosest and densest states.
Determination of relative density is helpful in evaluating compaction state of coarse grained soils and also assessing the safe bearing capacity in case of sandy soils.
Relative Density = (emax - e)/ (emax - emin)
Where,
emax = void ratio of coarse grained soil (cohesionless) in its loosest state.
emin = void ratio of coarse grained soil (cohesionless) in its densest state.
e = void ratio of coarse grained soil (cohesionless) in its natural existing state in the field.
We have,
e =VV/VS
Yd = G YW/(1+e)
Therefore,
e = {G YW/Yd} - 1
So, "e" is inversely proportional to "Yd"
Explanation: