Proctor Compaction Test and Degree of Saturation

The Proctor compaction test is a laboratory method of experimentally determining the optimal moisture content at which a given soil type will become most dense and achieve its maximum dry density. In this test, a soil specimen is compacted into a mold at various moisture contents and subjected to a specific amount of compaction effort. The bulk density of the specimen is then measured and used to determine the optimal moisture content.

The degree of saturation of a soil specimen is defined as the ratio of the volume of water in the specimen to the total pore volume. It is a measure of how much water is present in the soil compared to its total pore space. It is an important parameter in geotechnical engineering as it affects the soil's strength and compressibility.

Calculation of Degree of Saturation

To calculate the degree of saturation of the soil specimen, we need to know its bulk density and moisture content. We are given that the bulk density of the specimen is 19 KN/m3 and the moisture content is 15%. We also know that the specific gravity of the soil (G) is 2.7.

The first step is to calculate the dry density of the soil specimen. This is done using the formula:

Dry density (ρd) = bulk density / (1 + moisture content)

Substituting the given values, we get:

ρd = 19 / (1 + 0.15) = 16.52 KN/m3

Next, we need to calculate the void ratio of the soil specimen. This is done using the formula:

e = (Gs / (1 + Gs)) x (ρd / ρw) - 1

Where Gs is the specific gravity of the soil, ρd is the dry density of the soil, and ρw is the density of water (1000 kg/m3).

Substituting the given values, we get:

e = (2.7 / (1 + 2.7)) x (16.52 / 1000) - 1 = 0.67

Finally, we can calculate the degree of saturation using the formula:

S = (1 - e) x 100%

Substituting the value of e, we get:

S = (1 - 0.67) x 100% = 33%

Therefore, the degree of saturation of the soil specimen is 33%.

Conclusion

In conclusion, the degree of saturation of a soil specimen can be calculated using its bulk density, moisture content, and specific gravity. In the Proctor compaction test, the degree of saturation is an important parameter to consider as it affects the soil's strength and compressibility.

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