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Kansas Soils/Geotechnical Special
Inspector Qualification Advanced 100-
Question Practice Exam 2026 |
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. What is the primary purpose of performing an in-place soil density test
during structural fill placement?
A. To determine the soil's liquid limit
B. To verify that the placed soil has achieved the specified compaction
requirement
C. To determine the soil's mineralogy
D. To determine the groundwater elevation
Answer: B. To verify that the placed soil has achieved the specified compaction
requirement
Rationale: In-place density testing compares the field density with the
laboratory maximum dry density and the project-specified percentage of
compaction.
, 2. A soil has a maximum dry density of 121.5 pcf from the approved Proctor
test. The specification requires 95% compaction. What is the minimum
acceptable dry density?
A. 110.25 pcf
B. 113.40 pcf
C. 115.43 pcf
D. 121.50 pcf
Answer: C. 115.43 pcf
Rationale: Required dry density = 121.5 × 0.95 = 115.425 pcf, or approximately
115.43 pcf.
3. Which soil classification system is commonly used to classify soils for
engineering purposes based on grain size and plasticity?
A. ACI
B. AWS
C. USCS
D. ASTM C94
Answer: C. USCS
Rationale: The Unified Soil Classification System classifies soils primarily using
particle-size distribution and Atterberg limits.
4. In the Unified Soil Classification System, a soil designated CL is generally:
A. Clean gravel
B. Low-plasticity clay
C. High-plasticity clay
D. Well-graded sand
Answer: B. Low-plasticity clay
Rationale: CL represents inorganic clays of low to medium plasticity, generally
having a liquid limit below 50.
, 5. A soil sample has a liquid limit of 42 and a plastic limit of 18. What is its
plasticity index?
A. 18
B. 24
C. 42
D. 60
Answer: B. 24
Rationale: Plasticity index is calculated as PI = LL − PL = 42 − 18 = 24.
6. Which field condition most directly indicates that a cohesive soil may be
too wet for proper compaction?
A. Soil breaks apart immediately when handled
B. Soil becomes excessively plastic and pumps under equipment
C. Soil contains visible gravel
D. Soil is uniformly dry and loose
Answer: B. Soil becomes excessively plastic and pumps under equipment
Rationale: Excess moisture can prevent adequate particle rearrangement and
cause pumping, rutting, and unstable compaction.
7. What is the principal difference between standard-effort and modified-
effort Proctor compaction?
A. Modified effort uses a different soil classification system
B. Modified effort applies substantially greater compactive energy
C. Standard effort can only be performed on clay
D. Modified effort does not determine optimum moisture
Answer: B. Modified effort applies substantially greater compactive energy
Rationale: Modified Proctor testing uses substantially greater compaction
energy than standard Proctor testing and therefore commonly produces higher
maximum dry density and lower optimum moisture content.
, 8. Which test is commonly used to determine the liquid limit, plastic limit, and
plasticity index of a soil?
A. ASTM D4318
B. ASTM D1556
C. ASTM D6938
D. ASTM D854
Answer: A. ASTM D4318
Rationale: ASTM D4318 covers liquid limit, plastic limit, and plasticity index of
soils.
9. What does a high plasticity index generally indicate?
A. Very low clay activity or plasticity
B. A greater range of moisture contents over which the soil remains plastic
C. Absence of fines
D. High permeability
Answer: B. A greater range of moisture contents over which the soil remains
plastic
Rationale: PI represents the range between liquid and plastic limits and
generally increases with plasticity of the fine-grained fraction.
10.Which field test determines in-place soil density using a calibrated nuclear
gauge?
A. ASTM D6938
B. ASTM D2487
C. ASTM D4318
D. ASTM D854
Answer: A. ASTM D6938
Rationale: ASTM D6938 covers in-place density and water content of soil and
soil-aggregate using nuclear methods.
Kansas Soils/Geotechnical Special
Inspector Qualification Advanced 100-
Question Practice Exam 2026 |
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. What is the primary purpose of performing an in-place soil density test
during structural fill placement?
A. To determine the soil's liquid limit
B. To verify that the placed soil has achieved the specified compaction
requirement
C. To determine the soil's mineralogy
D. To determine the groundwater elevation
Answer: B. To verify that the placed soil has achieved the specified compaction
requirement
Rationale: In-place density testing compares the field density with the
laboratory maximum dry density and the project-specified percentage of
compaction.
, 2. A soil has a maximum dry density of 121.5 pcf from the approved Proctor
test. The specification requires 95% compaction. What is the minimum
acceptable dry density?
A. 110.25 pcf
B. 113.40 pcf
C. 115.43 pcf
D. 121.50 pcf
Answer: C. 115.43 pcf
Rationale: Required dry density = 121.5 × 0.95 = 115.425 pcf, or approximately
115.43 pcf.
3. Which soil classification system is commonly used to classify soils for
engineering purposes based on grain size and plasticity?
A. ACI
B. AWS
C. USCS
D. ASTM C94
Answer: C. USCS
Rationale: The Unified Soil Classification System classifies soils primarily using
particle-size distribution and Atterberg limits.
4. In the Unified Soil Classification System, a soil designated CL is generally:
A. Clean gravel
B. Low-plasticity clay
C. High-plasticity clay
D. Well-graded sand
Answer: B. Low-plasticity clay
Rationale: CL represents inorganic clays of low to medium plasticity, generally
having a liquid limit below 50.
, 5. A soil sample has a liquid limit of 42 and a plastic limit of 18. What is its
plasticity index?
A. 18
B. 24
C. 42
D. 60
Answer: B. 24
Rationale: Plasticity index is calculated as PI = LL − PL = 42 − 18 = 24.
6. Which field condition most directly indicates that a cohesive soil may be
too wet for proper compaction?
A. Soil breaks apart immediately when handled
B. Soil becomes excessively plastic and pumps under equipment
C. Soil contains visible gravel
D. Soil is uniformly dry and loose
Answer: B. Soil becomes excessively plastic and pumps under equipment
Rationale: Excess moisture can prevent adequate particle rearrangement and
cause pumping, rutting, and unstable compaction.
7. What is the principal difference between standard-effort and modified-
effort Proctor compaction?
A. Modified effort uses a different soil classification system
B. Modified effort applies substantially greater compactive energy
C. Standard effort can only be performed on clay
D. Modified effort does not determine optimum moisture
Answer: B. Modified effort applies substantially greater compactive energy
Rationale: Modified Proctor testing uses substantially greater compaction
energy than standard Proctor testing and therefore commonly produces higher
maximum dry density and lower optimum moisture content.
, 8. Which test is commonly used to determine the liquid limit, plastic limit, and
plasticity index of a soil?
A. ASTM D4318
B. ASTM D1556
C. ASTM D6938
D. ASTM D854
Answer: A. ASTM D4318
Rationale: ASTM D4318 covers liquid limit, plastic limit, and plasticity index of
soils.
9. What does a high plasticity index generally indicate?
A. Very low clay activity or plasticity
B. A greater range of moisture contents over which the soil remains plastic
C. Absence of fines
D. High permeability
Answer: B. A greater range of moisture contents over which the soil remains
plastic
Rationale: PI represents the range between liquid and plastic limits and
generally increases with plasticity of the fine-grained fraction.
10.Which field test determines in-place soil density using a calibrated nuclear
gauge?
A. ASTM D6938
B. ASTM D2487
C. ASTM D4318
D. ASTM D854
Answer: A. ASTM D6938
Rationale: ASTM D6938 covers in-place density and water content of soil and
soil-aggregate using nuclear methods.
