---
title: "Basic requirements of classification"
subject: "Soil Mechanics"
chapter: 3
key: "semester_4/soil_mechanics:basic-requirements-classification"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/basic-requirements-classification
site: BCT Engineering
---

# Basic requirements of classification

Soil Mechanics · Chapter 3: Soil Identifications and Classification

- Asked in: 2078 Poush, 2 marks; 2076 Baisakh, 1 marks (asked 2 times)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/soil_mechanics/basic-requirements-classification
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-3

## Question

What are the basic requirements of soil classification?

## Short answer

A soil classification should be simple, use inexpensive standard index tests (grain size, Atterberg limits), group soils of similar engineering behaviour, have unambiguous boundaries for consistency, employ systematic nomenclature, be widely accepted and linked to experience, and cover all soil types.

## Answer

A good soil classification system should:
1. Be **simple**, easy to learn and to use, with a few clear groups.
2. Use **standard index tests** that are quick and cheap (grain size, Atterberg limits).
3. Place soils of **similar engineering behaviour** in the same group.
4. Use **clear boundaries** so that different engineers get the same classification.
5. Use a **systematic nomenclature** (symbols) that conveys properties of the soil.
6. Be **accepted** widely and linked to experience, so that behaviour can be predicted.
7. Cover **all types of soil**, coarse and fine, organic and inorganic.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. A good classification should place in the same group
   A. soils of similar engineering behaviour
   B. soils of the same colour
   C. soils from the same site
   D. soils with the same age
   Answer: A. Groups should predict behaviour. (Key point: Grouping requirement)

2. Which tests should classification rely on?
   A. Triaxial and consolidation tests
   B. Quick, cheap index tests like grain size and Atterberg limits
   C. Full field load tests
   D. Chemical analysis
   Answer: B. Simple standard tests make it practical. (Key point: Tests used)

3. A good system should
   A. classify only coarse soils
   B. avoid symbols
   C. cover all soil types with clear boundaries and systematic symbols
   D. use personal judgement for boundaries
   Answer: C. Clear boundaries give the same result for different engineers. (Key point: Coverage)

## Related in Soil Mechanics

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