Moisture Content of a Soil by Oven Drying Method (the most standard method used in soil mechanics and geotechnical engineering):

Moisture Content of a Soil by Oven Drying Method (the most standard method used in soil mechanics and geotechnical engineering):

                             https://youtu.be/F3mUFlTkziw

---

Moisture Content Determination by Oven Drying Method

Objective

To determine the natural water (moisture) content of a soil sample by oven drying method.

---

Apparatus Required

• Soil sample

• Non-corrodible container with lid (usually aluminum)

• Balance with accuracy of 0.01 g

• Oven (thermostatically controlled, maintained at 105°C – 110°C)

• Desiccator (to cool sample without absorbing atmospheric moisture)

• Tongs or gloves (for safety when handling hot containers)

---

Theory

• Moisture content (w):
  The ratio of the mass of water to the mass of dry soil, expressed as a percentage.

  $$w = \frac{M_w}{M_s} \times 100$$

  Where:
  $M_w =$ Mass of water
  $M_s =$ Mass of dry soil

---

Procedure

1. Preparation

   • Clean and dry the container, then record its mass as $M_1$.

2. Weighing wet soil

   • Place a small soil sample (20–30 g for fine soils; 50–100 g for coarse soils) into the container.

   • Weigh container + wet soil, record as $M_2$.

3. Drying in oven

   • Place the container (with soil) in a thermostatically controlled oven at 105–110°C.

   • Dry for at least 24 hours (or until constant mass is achieved).

4. Cooling

   • Remove container carefully, place in a desiccator to cool to room temperature (avoids moisture absorption).

5. Weighing dry soil

   • Weigh the container + dry soil, record as $M_3$.

---

Calculations

1. Mass of wet soil = $M_2 - M_1$

2. Mass of dry soil = $M_3 - M_1$

3. Mass of water = $(M_2 - M_1) - (M_3 - M_1) = M_2 - M_3$

4. Moisture Content (w):

   $$w = \frac{M_2 - M_3}{M_3 - M_1} \times 100 \, \%$$

---

Result

The moisture content of the given soil sample = ___ % (to two decimal places).

---

Notes

• For gypsum and organic soils, drying temperature is kept below 80°C to avoid decomposition.

• The oven-drying method is the standard reference method (as per IS:2720 Part II, ASTM D2216).

• Moisture content affects shear strength, compressibility, and permeability of soils—critical for foundation design.