Question

Which of the following step is NOT associated with particle size analysis?

• A. Dispersion
• B. Fractionation
• C. Flocculation
• D. Sedimentation

Hint:

Size analysis goal: "Individualize" the particles.
Dispersion = Good for analysis.
Flocculation = Bad for analysis (good for soil structure in the field!).
Without dispersion, you are measuring "aggregates," not "particles."

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
Particle size analysis (mechanical analysis) is the process of determining the percentage of sand, silt, and clay in a soil. The question asks to identify the process that is detrimental or unrelated to this analysis.
Detailed Explanation:

• Dispersion (Associated):
This is the most critical first step. Soil particles are naturally clumped into "aggregates." To measure the size of individual particles, these clumps must be broken apart using chemical dispersing agents (like Sodium Hexametaphosphate/Calgon) and mechanical shaking.

• Fractionation (Associated):
This refers to the physical separation of the soil into different size classes, often using sieves for sand fractions.

• Sedimentation (Associated):
This is the principle used for silt and clay determination (Pipette/Hydrometer methods). It relies on Stokes Law, where larger particles settle faster in a column of water than smaller ones.

• Flocculation (NOT Associated):
Flocculation is the process where individual clay particles come together to form clumps (flocs).
If flocculation occurs during size analysis, a group of tiny clay particles will behave like a single large silt or sand particle, leading to gross errors in the results.
The purpose of particle size analysis is to "destroy" flocculation through "dispersion."

Step 2: Final Answer:
Flocculation is the opposite of what is required for accurate particle size analysis; therefore, it is not an associated step.