The document discusses geotechnical engineering principles, focusing on soil classification systems established by ASTM and AASHTO. It categorizes soils into eight groups based on their properties and provides practice problems for applying these classification methods. Additionally, it mentions a comparison between the AASHTO and FAA soil classification systems.

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Geotechnical Engineering–I [CE-221]
BSc Civil Engineering – 4th Semester
by
Dr. Muhammad Irfan
Assistant Professor
Civil Engg. Dept. – UET Lahore
Email: mirfan1@msn.com
Lecture Handouts: https://groups.google.com/d/forum/2016session-geotech-i
Lecture # 12
2-Mar-2018

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→ Classification procedure standardized by ASTM D3282 and
AASHTO M145.
→ Soil rating for subgrade construction.
→ Soils classified into 8 groups (+ several subgroups);
A-1 (best) to A-8 (worst).
→ Organic soils (peat and muck) assigned group A-8.
→ Required tests are sieve analysis and Atterberg limits.
AASHTO Soil Classification

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A4 ~ A7A1 ~ A3
Granular Materials Silt-clay Materials
LL and PI separates silty materials from
clayey materials
LL and PI separates silty materials from
clayey materials (only for A2 group)
AASHTO Soil Classification
(ASTM D3282; AASHTO M145)
A-1 (0)
Group Number Group Index
Example
 35% pass No. 200 sieve > 35% pass No. 200 sieve

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AASHTO Classification Chart
Note:
First group from the left to fit test data is the correct AASHTO classification.
(Coarse-grained Soils)

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AASHTO Classification Chart
Note:
First group from the left to fit test data is the correct AASHTO classification.
(Fine-grained Soils)

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Range of LL and PI for soils in groups A-2, A-4, A-5, A-6, and A-7.
AASHTO Plasticity Chart

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Practice Problem #4

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Note:
First group from the left to fit test data is the correct AASHTO classification.
Practice Problem #4

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A-7-5 soil
Practice Problem #4

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Practice Problem #4

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Classify the following soil Using AASHTO System. Given:
% passing No. 10 = 100;
% passing No. 40 = 80;
% passing No.200 = 58
LL = 30; PI = 10
Practice Problem #5
GI=3
A-4(3)

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CONCLUDED
REFERENCE MATERIAL
An Introduction to Geotechnical Engineering (2nd Edition)
By R. D. Holtz, W. D. Kovacs and T. C. Sheahan
Chapter #3
Principles of Geotechnical Engineering – (7th Edition)
Braja M. Das
Chapter #5

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Two commonly used classification system:
1. Unified Soil Classification System (USCS)
 preferred by Geotechnical engineers
2. American Association of State Highway and
Transportation Officials (AASHTO) System
 preferred by Transportation engineers
SOIL CLASSIFICATION
3. Federal Aviation Administration (FAA) Soil
Classification System

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Federal Aviation Administration
(FAA) Soil Classification
Equivalent
to AASHTO
A-8 soil

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Federal Aviation Administration
(FAA) Soil Classification

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P10 = 80% P40 = 52% P200 = 20%
LL = 18 PI = 4
Given data
Obtained from
gradation curve &
Atterberg Limit tests
Practice Problem #1

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Classify the following soil Using FAA Classification System. Given:
% passing No. 10 = 100;
% passing No. 40 = 80;
% passing No.200 = 58
LL = 30; PI = 9
Practice Problem #2