---
title: "Classify soil, No. 4 70%, No. 200 30%"
subject: "Soil Mechanics"
chapter: 3
key: "semester_4/soil_mechanics:classify-soil-no4-no200-ll33"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/classify-soil-no4-no200-ll33
site: BCT Engineering
---

# Classify soil, No. 4 70%, No. 200 30%

Soil Mechanics · Chapter 3: Soil Identifications and Classification

- Asked in: 2078 Baisakh, 4 marks
- Video: [Soil Classification by USCS](https://www.youtube.com/watch?v=bgFqeXiND9c) — Dr. Maria Cecilia Marcos
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/soil_mechanics/classify-soil-no4-no200-ll33
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-3

## Question

Classify the following soil if the test results obtained from sieve analysis and consistency tests are given below: Percentage passing No. 4 sieve (4.75 mm) = 70%, percentage passing No. 200 sieve (0.075 mm) = 30%; liquid limit = 33% and plastic limit = 11%.

## Short answer

SC, clayey sand with gravel. Fines 30% (>12%) are classified by plasticity; sand dominates coarse fraction (40% sand vs 30% gravel). Ip=22 lies above A-line value 9.5, so fines are clayey.

## Answer

#### Given
Passing No. 4 $= 70\%$; passing No. 200 $= 30\%$; $w_L = 33\%$; $w_P = 11\%$.

$$
I_p = w_L - w_P = 33 - 11 = 22\%
$$

#### Step 1: Coarse or fine?
70% is retained on the No. 200 sieve, so the soil is **coarse-grained**.

#### Step 2: Gravel or sand?
- Gravel (retained on No. 4) $= 100 - 70 = 30\%$
- Sand $= 70 - 30 = 40\%$

Gravel is 30/70 = 43% of the coarse fraction (less than half), so the soil is **sand (S)**.

#### Step 3: Fines
Fines are 30% (more than 12%), so classify the fines with the plasticity chart.
$$
I_{p,A\text{-line}} = 0.73(33 - 20) = 9.5\%
$$
$I_p = 22$ is above the A-line and greater than 7: **clayey fines (C)**.

**Answer: SC, clayey sand (with gravel).**

## Check yourself

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

1. Ip = wL - wP =
   A. 22%
   B. 11%
   C. 44%
   D. 33%
   Answer: A. 33-11. (Key point: Ip)

2. Gravel is 30%, sand 40%, so soil is sand since gravel
   A. is above 12%
   B. is 43% of coarse fraction, under half
   C. is above 5%
   D. is above 20%
   Answer: B. 30/70. (Key point: Sand)

3. Fines of 30% > 12% are classed by
   A. grading
   B. origin
   C. plasticity chart
   D. sieve 4
   Answer: C. Atterberg limits are used. (Key point: Fines)

4. Ip=22 above A-line (9.5) and > 7 gives
   A. SM
   B. SP
   C. GC
   D. SC
   Answer: D. Clayey sand. (Key point: Result)

## Related in Soil Mechanics

- [ISSCS classification, 55% passing 200](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aissc-classify-passing-55) — Soil Mechanics, chapter 3
- [USCS classification, 75 micron 39%](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Auscs-classify-75micron-39-percent) — Soil Mechanics, chapter 3
- [AASHTO classification of inorganic soil](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aaashto-classify-inorganic-soil) — Soil Mechanics, chapter 3
- [USCS classification, 75 micron 62%](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Auscs-classify-75micron-62-percent) — Soil Mechanics, chapter 3
- [USCS classification, 75 micron 8%](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Auscs-classify-75micron-8-percent) — Soil Mechanics, chapter 3
- [USCS classification, 75 micron 4%](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Auscs-classify-sieve-four-percent) — Soil Mechanics, chapter 3

## Related in other subjects

- [Why different consistency tests, ductility](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aconsistency-tests-why-ductility) — Transportation Engineering I, chapter 6
- [Characteristic strength from test results](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Acharacteristic-strength-30-28) — Concrete Technology and Masonry Structure, chapter 5
- [No-load and blocked rotor tests of induction motor](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machines_i%3Aim-noload-blocked-rotor-test-explain) — Electrical Machines I, chapter 5
- [Induction motor equivalent circuit from no-load and blocked rotor tests](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machines_i%3Aim-noload-blocked-400v-equivalent) — Electrical Machines I, chapter 5