Determination of Field Density of Soil by Core Cutter Method

 

Experiment No.:

Date:

---

Experiment Title:

Determination of Field Density of Soil by Core Cutter Method

---

Objective:

To determine the field density of soil using the Core Cutter Method, following the procedure outlined in IS 2720 (Part 29): 1975.

---

Apparatus Required:

1. Core Cutter (Standard dimensions: 100 mm internal diameter and 130 mm height)
2. Steel Rammer (9 kg weight with a drop height of 310 mm)
3. Weighing Balance (Accurate to 1 g)
4. Steel Rule (For measuring the dimensions of the core cutter)
5. Straight Edge (For trimming excess soil from the core cutter)
6. Moisture Content Containers
7. Oven (For moisture content determination)
8. Desiccator
9. Chisel and Hammer (For removing the core cutter from the soil)

---

Theory:

The Core Cutter Method is used to determine the in-situ density of soil, which is essential for analyzing soil compaction at construction sites. In this method, a core cutter is driven into the soil, and the soil sample collected in the cutter is weighed to calculate the field density using the following formula:

$$ρ = \frac{W_s}{V_c}$$

Where:

• ρ = Field Density (g/cm³ or kg/m³)
• W_s = Weight of soil sample (g or kg)
• V_c = Volume of the core cutter (cm³ or m³), calculated as $V_c = \pi \times \left(\frac{d}{2}\right)^2 \times h$
• d = Internal diameter of the core cutter (cm)
• h = Height of the core cutter (cm)

---

Procedure:

1. Measure the Core Cutter:

   • Measure the internal diameter (d) and height (h) of the core cutter using a steel rule and calculate its volume using the formula:
   $$V_c = \pi \times \left(\frac{d}{2}\right)^2 \times h$$

2. Drive the Core Cutter into Soil:

   • Place the core cutter on the soil surface.
   • Using the steel rammer, drive the cutter into the soil until its top is flush with the soil surface.

3. Extract the Core Cutter:

   • Carefully dig around the core cutter and extract it without disturbing the soil inside it.

4. Trim and Weigh the Soil:

   • Use a straight edge to trim off excess soil from the top and bottom of the core cutter.
   • Weigh the core cutter with the soil sample and record the weight as W1.

5. Weigh the Empty Core Cutter:

   • Weigh the empty core cutter and record its weight as W2.

6. Determine the Field Density:

   • Calculate the weight of the soil sample as:
   $$W_s = W1 - W2$$
   • Now calculate the field density (ρ) using the formula:
   $$ρ = \frac{W_s}{V_c}$$

7. Moisture Content Determination:

   • Take a small portion of the soil sample and place it in a moisture content container.
   • Dry the sample in an oven at 110°C for 24 hours and calculate the moisture content using the formula:
   $$w = \frac{W_w - W_d}{W_d} \times 100$$

   Where:

   • W_w = Weight of wet soil
   • W_d = Weight of dry soil

---

Observation Table:

Observation	Measurement
Weight of Core Cutter + Soil (W1)	______ g
Weight of Empty Core Cutter (W2)	______ g
Weight of Soil Sample (W_s = W1 - W2)	______ g
Volume of Core Cutter (V_c)	______ cm³
Field Density (ρ)	______ g/cm³
Moisture Content (w)	______ %

---

Results:

• The field density of the given soil sample is found to be _______ g/cm³.

---

Diagram of Core Cutter Method:

Conclusion:

The field density of the given soil sample was determined using the Core Cutter Method according to IS 2720 (Part 29): 1975. This method provides accurate field density, essential for analyzing soil compaction in construction projects.