CE 3B6 ; GEOTECHNICAL ENGINEERING LABORATORY
NAME:
DEJARLO, MICHELLE ANNE B.
COURSE & YEAR:
GROUP NO.:
DATE PERFORMED: 03/21/24
BSCE-3
4
DATE SUBMITTED: ______
GRADE: _________
EXPERIMENT NO. 6
CLASSIFICATION OF SOIL ACCORDING TO AASHTO
1.0 DISCUSSION
Soil is classified according to its physical properties. The arrangement of different soils with
respect to its properties are classified into groups and subgroups. Soils may be classified in
general ways as cohesive, fine grained or residual or other way around. However, this
classification is too wide in range of physical and engineering properties that is why, a more
refined classification system is necessary.
Classification of soil is important in engineering sense because this will give the engineer a
fairly good idea on the way soil will most likely behave. This will enable to choose the most
suitable type for a certain engineering project.
2.0 APPARATUS AND MATERIALS
o SIEVE ANALYSIS RESULT
o LIQUID LIMIT RESULT
o PLASTIC LIMIT RESULT
o AASHTO TABLE OF CLASSIFICATION
3.0 PROCEDURE
1. Prepare the data from the sieve analysis.
2. Use the AASHTO classification system as reference
3. Classify the soil.
4.0 DATA ANALYSIS
GEOTECHNICAL ENGINEERING 1
CIVIL ENGINEERING DEPARTMENT
AASHTO CLASSIFICATION OF SOIL
DATA SHEET
SIEVE SIZE
SOIL A
% FINER
SOIL B
% FINER
SOIL C
% FINER
NO.4
89.51
89.5
77.98
NO. 10
76.27
76.33
50.98
NO. 40
37.17
37.22
14.12
NO.60
29.53
29.58
4.73
NO.100
11.17
11.21
2.38
NO. 200
2.58
2.61
1.81
PAN
0
0
0
LL
19
0
0
PL
7
8
0
PI
12
8
0
SOIL
CLASSIFICATION
A-2-6
A-2-6
A-2-5
Soil Classification
According to AASHTRO classification table
Classification
System
SOIL A
SOIL B
SOIL C
General Classification
granular materials
granular materials
granular materials
Group Classification
A-2-6
A-2-6
A-2-5
Sieve Analysis
Percent Passing
#40(50 max)= N/A
#200(35 max)= 2.58
< 35, satisfied
#40(50 max)= N/A,
satisfied
#200(35 max)=
2.61< 35, satisfied
#40(35 max)= N/A,
satisfied
#200(35 max)=
1.81< 35, satisfied
Classification of
fraction passing
0.425 mm
PI (11 min)= 12 ,
Satisfied
PI (11 min)= 8 ,
Satisfied
PI (10 max)= 0 ,
Satisfied
Usual type of
significant consistent
materials
silty or clayey gravel
sand
silty or clayey gravel
sand
silty or clayey gravel
and sand
General Subgrade
Rating
excellent to good
excellent to good
excellent to good
Group Index
0
0
0
Soil Classification
A-2-6
A-2-6
A-2-5
SOLVE FOR THE GROUP INDEX USING THIS FORMULA:
5.0 CALCULATIONS
Sample Calculation for Group Index
●
●
Group Index of soils belonging to groups: A-1-a, A-1-b, A-2-4, A-2-5, and A-3 are
always zero.
When calculating the Group Index for soils that belong to groups A-2-6 and A-2-7, use
the partial Gi formula: GI= 0.01(F200-15)(PI-10).
SOIL A
GI= 0.01(F200-15)(PI-10)
=0.01(2.58-15)(12-10)
GI=-0.2484≈0
SOIL B
GI= 0.01(F200-15)(PI-10)
=0.01(2.61-15)(8-10)
GI=-0.2478≈0
SOIL C
GI=0
6.0 FIGURES AND DIAGRAMS
(Fig.1: seivng using sieve shaker)
This image shows using the sieve shaker to efficiently separate particles of different sizes within
a sample through different sieve sizes.
7.0 INTERPRETATIONS/ANALYSIS/CONCLUSION
Understanding soil properties holds significant importance in numerous engineering contexts,
especially in the realm of road construction. To streamline this process, the American
Association of State Highway and Transportation Officials (AASHTO) has devised a classification
system aimed at organizing soils based on their engineering characteristics. The primary
objective of this experiment is to classify three distinct soil samples, labeled as Soil A, Soil B,
and Soil C, according to the AASHTO classification criteria. This classification entails the
evaluation of parameters such as Liquid Limit (LL), Plastic Limit (PL), Plasticity Index (PI), and
Group Index (GI) to assign specific soil groups.
In detail, Soil A exhibits a Liquid Limit (LL) of 19 and a Plastic Limit (PL) of 12, resulting in a
Plasticity Index (PI) of 12 and a Group Index (GI) of 0. On the other hand, Soil B showcases a
Liquid Limit (LL) of 0 and a Plastic Limit (PL) of 8, resulting in a Plasticity Index (PI) of 8.
Despite possessing some plasticity, the Group Index (GI) remains at 0. Both Soil A and Soil B
are classified as silty or clayey gravel soil (A-2-6), indicating a notable presence of fines and
exhibiting cohesive properties that may pose challenges in construction due to its cohesive
nature.
Lastly, Soil C demonstrates a Liquid Limit (LL) of 17 and a Plastic Limit (PL) of 0, resulting in a
Plasticity Index (PI) of 0 and a Group Index (GI) of 0. Soil C is classified as silty or clayey gravel
sand (A-2-5), indicating dominance by silt particles. While lacking in plasticity, its classification
suggests potential cohesive properties due to the presence of fines.
In conclusion, this experiment effectively showcases the application of the AASHTO classification
system in organizing soils based on their engineering attributes. Soil classification plays a pivotal
role in assessing soil suitability for diverse construction projects. By scrutinizing parameters like
Liquid Limit, Plastic Limit, Plasticity Index, and Group Index, engineers can make well-informed
decisions regarding soil utilization and anticipate engineering challenges associated with varying
soil types.