Soil Compaction Test (Laboratory | Household)

Table of Contents

Laboratory procedure

procedure for the Proctor Soil Compaction Test with two sections presented as tables, and the rest in paragraph form, as requested:

Objective:

To determine the optimum moisture content (OMC) and maximum dry density (MDD) of a soil sample using standard compaction.

Materials Required:

Material	Description
Soil Sample	Approximately 5 kg of soil, sieved to 4.75 mm.
Compaction Mold	A mold with 1000 cm³ volume.
Compaction Hammer	2.5 kg hammer, 30 cm drop height.
Weighing Balance	Accurate to 0.01 g.
Measuring Cup	For water measurement.
Oven	For drying the soil sample.
Sieve	4.75 mm mesh size sieve.
Ruler or Caliper	For measuring the height of soil.
Straight Edge/Spatula	For leveling soil in the mold.
Water Content Apparatus	For measuring moisture content.

Procedure:

Preparation of Soil Sample:
- Dry the soil sample in an oven at 105°C to 110°C for at least 24 hours to remove all moisture. Weigh the dry soil and record the mass.
- After drying, sieve the soil through a 4.75 mm sieve to remove larger particles. The finer soil particles are then used for testing.
Prepare Soil for Different Moisture Contents:
- Take a portion of the soil (approximately 1 kg). Gradually add water to the soil, starting with a low moisture content. Mix thoroughly until the desired moisture content is achieved.
- Prepare multiple samples at different moisture levels (e.g., 4%, 6%, 8%, 10%, 12%) to test how the moisture content affects compaction.
Compaction of Soil in the Mold:
- Set up the mold on a flat, stable surface. Place the mold on a solid base, ensuring it is clean and dry.
- For each moisture content sample, divide the soil into 3 equal portions. Add the first portion to the mold and compact it by using a hammer (2.5 kg) dropped from 30 cm height, applying 25 blows per layer.
- Repeat the process for all layers until the mold is filled. After compacting each layer, use a spatula or straight edge to level the surface.
Measure the Compacted Soil:
- After compacting, carefully weigh the mold with the compacted soil inside it.
- Measure the height of the compacted soil in the mold using a ruler or caliper.
Extract the Compacted Soil:
- Remove the soil from the mold, breaking it up gently to avoid disturbing its structure. Weigh the extracted compacted soil.
Dry the Soil:
- Take a small portion of the compacted soil (approximately 100 g) and dry it in the oven at 105°C to 110°C for 24 hours. After drying, weigh the sample and calculate the moisture content.
- The formula for calculating moisture content is: Moisture Content (%)=Weight of Wet Soil−Weight of Dry SoilWeight of Dry Soil×100\text{Moisture Content (\%)} = \frac{\text{Weight of Wet Soil} – \text{Weight of Dry Soil}}{\text{Weight of Dry Soil}} \times 100Moisture Content (%)=Weight of Dry SoilWeight of Wet Soil−Weight of Dry Soil×100
Repeat for Different Moisture Contents:
- Repeat the compaction process for different moisture levels and record the results. This helps create a comprehensive data set to determine the optimal moisture content.

Calculation of Dry Density:

For each moisture content sample, calculate the dry density of the soil using the formula:Dry Density=Mass of Dry SoilVolume of Mold\text{Dry Density} = \frac{\text{Mass of Dry Soil}}{\text{Volume of Mold}}Dry Density=Volume of MoldMass of Dry Soil

Where:

Mass of Dry Soil is the weight of the compacted soil after drying.
Volume of Mold is 1000 cm³ (since the volume of the standard mold is 1 liter).

Plotting and Results:

After testing at various moisture contents, plot a graph of dry density versus moisture content. This will typically form a curve, showing an increase in dry density with increasing moisture content up to a peak, followed by a decrease as the soil becomes over-saturated with water.
The optimum moisture content (OMC) is the moisture content at which the maximum dry density (MDD) occurs. This is the point where compaction is most effective.

Conclusion:

The Proctor test provides essential information about soil compaction. By determining the optimum moisture content and maximum dry density, engineers can ensure that soil is adequately compacted for construction projects, such as foundations or roadbeds, ensuring long-term stability and durability.

Household Procedure

Materials Needed:

A measuring container (like a plastic bottle or any small container with a known volume)
A plastic bag or a cloth to cover the soil sample (optional, for cleaning)
A hammer, mallet, or a sturdy object for compacting
A ruler or measuring tape to measure the height of the soil
A scale (optional, for measuring mass)

Steps for Soil Compaction Test

Step	Description
1. Collect a Sample of Soil	Dig up a representative soil sample (about 1 liter) from the site you want to test. Remove large debris.
2. Fill a Container	Use a container (like a plastic bottle) and fill it with loose soil from the sample, leaving some extra soil above the top.
3. Compact the Soil	Tap the soil down in layers using a hammer or mallet to compact it effectively.
4. Measure the Compacted Soil Height	After compacting, measure the height of the soil using a ruler or measuring tape.
5. Compare with Loose Soil Volume	Measure the height difference between loose and compacted soil to see how much it has compacted.

To interpret the results:

If the soil compacts well and shows minimal air space, it indicates that the particles are tightly packed, suggesting the soil is dense and resistant to further compaction or water infiltration.

On the other hand, if the soil shows noticeable air spaces after compaction, it means the particles were not tightly packed, making it more susceptible to compaction from external forces like heavy machinery.

For a more thorough test, weighing the soil before and after compacting can help determine its density, although this is a rough estimate without precise lab equipment. This method provides a good, simple way to assess soil compaction without using specialized tools.

DIY Civil Testing