# HOW TO DETERMINE UNIT WEIGHT OR DENSITY OF SOIL?

## Purpose:

This laboratory is used to determine the density of undisturbed soils obtained by pushing or drilling a thin walled cylinder. Bulk density is the ratio of the mass of moist soil to the volume of the soil sample, and dry density is the ratio of the mass of dry soil to the volume of the soil sample.

## Standard Reference:

ASTM D 2937-00 Standard test for soil density by drive-cylinder method

## Importance:

This test is used to determine the density of a soil spot. This test can also be used to determine the density of denser soils used in the construction of structural fills, highway embankments or earth dams. This method is not recommended for organic or friable soils.

## Device:

• straight edge
• balance
• moisture can
• dry oven
• Vernier calliper

## Testing Process:

(1) Take out the soil sample from the cylinder using extruder.

(2) Cut a representative soil sample from the extracted sample.

(3) Set and record the length (Took), Diameter (D) and mass (MTea) soil sample.

(4) Determine and record soil moisture (woo,

(Note: If the soil is sandy or loose, weigh the cylinder and the soil sample together. Measure the dimensions of the soil sample within the cylinder. Take the soil sample out and weigh and determine the moisture content)

## Data Analysis:

(1) Determine the moisture content of the soil (click here to read the moisture content test procedure)

(2) Quantify the soil sample

v ,D2L) / 4 cm. In3

(3) Calculate the bulk density (ITea) Of clay

ITea = mTea/V g/cm. In3

or unit weight ITea ,Tea , Yes

(4) Calculate the dry density (ID) Of clay

ID , ITea/(1+w) g/cm. In3

or dry unit weight ID ,D* Yes

### article written by

Pro. Krishna Reddy, UIC

Er. Mukesh Kumar

Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.