ICC Soils Special Inspector Examination
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
Question 1
The primary purpose of a soils special inspection is to verify that soil-related
construction complies with:
A. Architectural drawings and aesthetic requirements
B. Structural steel standards and connections
C. Approved construction documents and geotechnical report recommendations
D. Contractor means and methods for cost efficiency
Answer: C. Approved construction documents and geotechnical report
recommendations. Soils special inspection ensures earthwork operations, fill
placement, and site preparation conform to the approved plans, specifications,
and the geotechnical engineering report. The special inspector is responsible for
verifying compliance with these documents, not contractor methods or aesthetic
considerations .
Question 2
Which document provides site-specific soil recommendations for foundation
design and construction?
A. The International Building Code (IBC)
B. The structural drawings prepared by the structural engineer
,C. The geotechnical engineering report
D. The standard soil classification chart from ASTM
Answer: C. The geotechnical engineering report. This document contains
subsurface investigation results, laboratory test data, and design
recommendations specific to the site. The geotechnical report is prepared by a
registered design professional and is essential reading for the soils special
inspector .
Question 3
Compaction of soil is primarily intended to:
A. Increase permeability and drainage characteristics
B. Reduce soil temperature and thermal conductivity
C. Increase density, shear strength, and load-bearing capacity while reducing
settlement
D. Improve soil color for aesthetic purposes
Answer: C. Increase density, shear strength, and load-bearing capacity while
reducing settlement. Proper compaction increases soil density by reducing void
space, which enhances strength, stability, and load-bearing capacity while
minimizing future settlement under applied loads .
Question 4
The most common field test used to measure in-place soil compaction is:
A. Sieve analysis for particle size distribution
B. Hydrometer test for fine-grained soil classification
C. Nuclear density test using a gauge with gamma and neutron sources
D. Atterberg limits test for plasticity determination
Answer: C. Nuclear density test using a gauge with gamma and neutron sources.
The nuclear density gauge is widely used in the field to measure in-place density
,(using gamma radiation from cesium-137) and moisture content (using neutron
emission from americium-241/beryllium) quickly and non-destructively .
Question 5
The International Building Code (IBC) references ASTM D1556 for:
A. The standard Proctor compaction test
B. The sand cone test method for in-place density
C. The nuclear gauge test method for density and moisture
D. The sieve analysis test for soil classification
Answer: B. The sand cone test method for in-place density. ASTM D1556 is the
standard test method for density and unit weight of soil in place by the sand
cone method. This method is applicable for soils without considerable amounts
of rock or coarse materials greater than 1.5 inches in diameter .
Question 6
What does the liquid limit (LL) test measure in soil?
A. The moisture content at which soil changes from solid to semi-solid state
B. The moisture content at which soil changes from liquid to plastic state
C. The moisture content at which soil changes from plastic to liquid state
D. The total amount of water a soil can absorb before saturation
Answer: C. The moisture content at which soil changes from plastic to liquid
state. The liquid limit is determined by ASTM D4318 and represents the
boundary between the plastic and liquid states. It is one of the Atterberg limits
used to classify fine-grained soils .
Question 7
The plasticity index (PI) is calculated as:
, A. Liquid limit plus plastic limit (LL + PL)
B. Plastic limit minus liquid limit (PL - LL)
C. Liquid limit minus plastic limit (LL - PL)
D. Plastic limit divided by liquid limit (PI ÷ LL)
Answer: C. Liquid limit minus plastic limit (LL - PL). The plasticity index is the
numerical difference between the liquid limit and the plastic limit. It indicates
the range of moisture content over which the soil remains plastic and is a key
parameter for soil classification .
Question 8
In the Unified Soil Classification System (USCS), which symbol represents inorganic
clay with low plasticity?
A. CH
B. CL
C. ML
D. SM
Answer: B. CL. In the USCS, CL designates inorganic clay of low plasticity (low to
medium compressibility). The "C" denotes clay and "L" indicates low plasticity.
This classification is based on Atterberg limits plotting below the A-line with PI
between 4 and 7 .
Question 9
Which soil type, according to USCS, passes the No. 200 sieve with a plasticity
index (PI) equal to or greater than 4 and plots on or above the A-line?
A. Silt (M)
B. Organic soil (O)
C. Clay (C)
D. Peat (Pt)
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
Question 1
The primary purpose of a soils special inspection is to verify that soil-related
construction complies with:
A. Architectural drawings and aesthetic requirements
B. Structural steel standards and connections
C. Approved construction documents and geotechnical report recommendations
D. Contractor means and methods for cost efficiency
Answer: C. Approved construction documents and geotechnical report
recommendations. Soils special inspection ensures earthwork operations, fill
placement, and site preparation conform to the approved plans, specifications,
and the geotechnical engineering report. The special inspector is responsible for
verifying compliance with these documents, not contractor methods or aesthetic
considerations .
Question 2
Which document provides site-specific soil recommendations for foundation
design and construction?
A. The International Building Code (IBC)
B. The structural drawings prepared by the structural engineer
,C. The geotechnical engineering report
D. The standard soil classification chart from ASTM
Answer: C. The geotechnical engineering report. This document contains
subsurface investigation results, laboratory test data, and design
recommendations specific to the site. The geotechnical report is prepared by a
registered design professional and is essential reading for the soils special
inspector .
Question 3
Compaction of soil is primarily intended to:
A. Increase permeability and drainage characteristics
B. Reduce soil temperature and thermal conductivity
C. Increase density, shear strength, and load-bearing capacity while reducing
settlement
D. Improve soil color for aesthetic purposes
Answer: C. Increase density, shear strength, and load-bearing capacity while
reducing settlement. Proper compaction increases soil density by reducing void
space, which enhances strength, stability, and load-bearing capacity while
minimizing future settlement under applied loads .
Question 4
The most common field test used to measure in-place soil compaction is:
A. Sieve analysis for particle size distribution
B. Hydrometer test for fine-grained soil classification
C. Nuclear density test using a gauge with gamma and neutron sources
D. Atterberg limits test for plasticity determination
Answer: C. Nuclear density test using a gauge with gamma and neutron sources.
The nuclear density gauge is widely used in the field to measure in-place density
,(using gamma radiation from cesium-137) and moisture content (using neutron
emission from americium-241/beryllium) quickly and non-destructively .
Question 5
The International Building Code (IBC) references ASTM D1556 for:
A. The standard Proctor compaction test
B. The sand cone test method for in-place density
C. The nuclear gauge test method for density and moisture
D. The sieve analysis test for soil classification
Answer: B. The sand cone test method for in-place density. ASTM D1556 is the
standard test method for density and unit weight of soil in place by the sand
cone method. This method is applicable for soils without considerable amounts
of rock or coarse materials greater than 1.5 inches in diameter .
Question 6
What does the liquid limit (LL) test measure in soil?
A. The moisture content at which soil changes from solid to semi-solid state
B. The moisture content at which soil changes from liquid to plastic state
C. The moisture content at which soil changes from plastic to liquid state
D. The total amount of water a soil can absorb before saturation
Answer: C. The moisture content at which soil changes from plastic to liquid
state. The liquid limit is determined by ASTM D4318 and represents the
boundary between the plastic and liquid states. It is one of the Atterberg limits
used to classify fine-grained soils .
Question 7
The plasticity index (PI) is calculated as:
, A. Liquid limit plus plastic limit (LL + PL)
B. Plastic limit minus liquid limit (PL - LL)
C. Liquid limit minus plastic limit (LL - PL)
D. Plastic limit divided by liquid limit (PI ÷ LL)
Answer: C. Liquid limit minus plastic limit (LL - PL). The plasticity index is the
numerical difference between the liquid limit and the plastic limit. It indicates
the range of moisture content over which the soil remains plastic and is a key
parameter for soil classification .
Question 8
In the Unified Soil Classification System (USCS), which symbol represents inorganic
clay with low plasticity?
A. CH
B. CL
C. ML
D. SM
Answer: B. CL. In the USCS, CL designates inorganic clay of low plasticity (low to
medium compressibility). The "C" denotes clay and "L" indicates low plasticity.
This classification is based on Atterberg limits plotting below the A-line with PI
between 4 and 7 .
Question 9
Which soil type, according to USCS, passes the No. 200 sieve with a plasticity
index (PI) equal to or greater than 4 and plots on or above the A-line?
A. Silt (M)
B. Organic soil (O)
C. Clay (C)
D. Peat (Pt)
