Question

A cohesive soil yields a maximum dry density of 16 kN/m³ during a standard Proctor Compaction test. What would be its void ratio if the specific gravity is 2.60 (Assume γ_w = 10 kN/m³)
1. 0.552
2. 0.625
3. 0.712
4. 0.583

Answer 1

Correct Answer - Option 2 : 0.625

Concepts:

The dry density (γ) is related to void ratio(e) and specific gravity (G) as:

\(\gamma_d = \frac{G \gamma_w}{1 + e}\)

 Calculation:

Given:  γ = 16 kN/m³; G = 2.6, e =?

Using the relation,

\(\gamma_d = \frac{G\gamma_w}{1 + e}\)

\(16= \frac{2.6 \times 10}{1 + e}\)

∴ e = 0.625

Important Point:

• Indian Standard Light Compaction Test is similar to Standard Proctor Test and Indian Standard Heavy Compaction Test similar to Modified Proctor Test.
• The basic difference in these two test is given as:

Parameter	Indian Standard Light Compaction Test	Indian Standard Heavy Compaction Test
Mould Size	Soil is compacted in 1000 cm3.	Soil is compacted in 1000 cm3.
No of layers	3 layers	5 layers
Nos. of Blow	25 per layer	25 per layer
Weight of hammer	2.6 kg	4.9 Kg
Height of fall of hammer	310 mm	450 mm