ICC ECP Soils Plans Module Exam
Questions & Correct Answers Verified
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1. A soil particle with a diameter of 0.002 mm is classified by the ICC ECP module as:
A) Sand
B) Silt
C) Clay
D) Gravel
Answer: C) Clay
Rationale: In standard soil classification systems used in construction plans (including
ICC ECP context), clay particles are defined as having a diameter less than 0.002 mm. Silt
ranges from 0.002 mm to 0.075 mm, sand from 0.075 mm to 4.75 mm, and gravel above
4.75 mm.
2. Which type of soil has the highest plasticity and greatest shrink-swell potential?
A) Silty sand
B) Well-graded gravel
C) High-plasticity clay (CH)
D) Low-plasticity silt (ML)
Answer: C) High-plasticity clay (CH)
Rationale: CH soils exhibit high plasticity index and are most susceptible to volume
,changes with moisture variation. This shrink-swell potential is critical for foundation
design and is a key concern in the ICC ECP soils module.
3. According to the Unified Soil Classification System (USCS) referenced in ICC ECP
exams, the symbol "GW" stands for:
A) Gravel with well-graded sand
B) Well-graded gravel with little or no fines
C) Silty gravel with good drainage
D) Poorly graded weathered gravel
Answer: B) Well-graded gravel with little or no fines
Rationale: In USCS, the first letter indicates major soil type (G=gravel), second indicates
gradation (W=well-graded). Well-graded gravel has a wide range of particle sizes.
4. A soil sample fails a standard Proctor compaction test at 16% moisture content with
maximum dry density of 1.95 g/cm³. If field dry density is 1.75 g/cm³, the percent
compaction is:
A) 89.7%
B) 90.4%
C) 91.2%
D) 92.6%
Answer: A) 89.7%
Rationale: Percent compaction = (field dry density / max dry density) × 100 =
(1.75/1.95)×100 = 89.74%. Most ICC ECP specifications require ≥95% for structural fills.
5. The concept of "effective stress" in soil mechanics is most critical for predicting:
A) Soil color
B) Shear strength and settlement
C) Organic content
D) Soil pH
,Answer: B) Shear strength and settlement
Rationale: Effective stress (total stress minus pore water pressure) determines
intergranular friction and therefore shear strength. Settlement calculations rely on
effective stress changes. The ICC ECP exam emphasizes effective stress for foundation
design.
6. Which of the following soils would be most suitable for use as a select backfill behind
a retaining wall per ICC ECP recommendations?
A) High-plasticity clay (CH)
B) Uniform fine sand (SP)
C) Well-graded gravel with sand (GW-GM)
D) Organic silt (OH)
Answer: C) Well-graded gravel with sand (GW-GM)
Rationale: Free-draining granular soils with low plasticity reduce hydrostatic pressure on
retaining walls. CH and OH retain water; SP lacks gradation for stability. GW-GM
provides drainage and mechanical stability.
7. Using the Atterberg limits: Liquid Limit = 55, Plastic Limit = 25. The Plasticity Index is:
A) 20
B) 25
C) 30
D) 55
Answer: C) 30
Rationale: Plasticity Index (PI) = Liquid Limit - Plastic Limit = 55 - 25 = 30. PI indicates
soil plasticity range and is used in USCS classification.
8. A soil is classified as "CL" in USCS. This means:
A) Clayey sand with low plasticity
B) Low-plasticity clay of low compressibility
C) Silty clay with high plasticity
D) Organic clay
, Answer: B) Low-plasticity clay of low compressibility
Rationale: "C" = clay, "L" = low plasticity (LL < 50, PI ≈ 7-18). CL soils have moderate
shrink-swell potential and are common subgrade soils.
9. In standard Proctor compaction test (ASTM D698), the compactive effort is
approximately:
A) 12,400 ft-lbf/ft³
B) 20,000 ft-lbf/ft³
C) 56,000 ft-lbf/ft³
D) 70,000 ft-lbf/ft³
Answer: A) 12,400 ft-lbf/ft³
Rationale: Standard Proctor uses a 5.5 lb hammer falling 12 inches for 25 blows on 3
layers. Modified Proctor uses higher effort (56,250 ft-lbf/ft³). ICC ECP exam distinguishes
between these.
10. Field density test results show a wet density of 120 lb/ft³ and moisture content of
15%. The dry density is closest to:
A) 102 lb/ft³
B) 104 lb/ft³
C) 108 lb/ft³
D) 110 lb/ft³
Answer: B) 104 lb/ft³
Rationale: Dry density = wet density / (1 + w/100) = 120/(1.15) = 104.35 lb/ft³. Dry
density is required for percent compaction calculations.
11. Which of the following is NOT a typical use of a geotechnical report in plan review
per ICC ECP?
A) Determining bearing capacity for shallow foundations
B) Selecting appropriate stormwater pipe material color
C) Assessing lateral earth pressures on retaining walls
D) Evaluating settlement potential of compressible layers
Questions & Correct Answers Verified
Plus Rationales 2026 | Instant Download
1. A soil particle with a diameter of 0.002 mm is classified by the ICC ECP module as:
A) Sand
B) Silt
C) Clay
D) Gravel
Answer: C) Clay
Rationale: In standard soil classification systems used in construction plans (including
ICC ECP context), clay particles are defined as having a diameter less than 0.002 mm. Silt
ranges from 0.002 mm to 0.075 mm, sand from 0.075 mm to 4.75 mm, and gravel above
4.75 mm.
2. Which type of soil has the highest plasticity and greatest shrink-swell potential?
A) Silty sand
B) Well-graded gravel
C) High-plasticity clay (CH)
D) Low-plasticity silt (ML)
Answer: C) High-plasticity clay (CH)
Rationale: CH soils exhibit high plasticity index and are most susceptible to volume
,changes with moisture variation. This shrink-swell potential is critical for foundation
design and is a key concern in the ICC ECP soils module.
3. According to the Unified Soil Classification System (USCS) referenced in ICC ECP
exams, the symbol "GW" stands for:
A) Gravel with well-graded sand
B) Well-graded gravel with little or no fines
C) Silty gravel with good drainage
D) Poorly graded weathered gravel
Answer: B) Well-graded gravel with little or no fines
Rationale: In USCS, the first letter indicates major soil type (G=gravel), second indicates
gradation (W=well-graded). Well-graded gravel has a wide range of particle sizes.
4. A soil sample fails a standard Proctor compaction test at 16% moisture content with
maximum dry density of 1.95 g/cm³. If field dry density is 1.75 g/cm³, the percent
compaction is:
A) 89.7%
B) 90.4%
C) 91.2%
D) 92.6%
Answer: A) 89.7%
Rationale: Percent compaction = (field dry density / max dry density) × 100 =
(1.75/1.95)×100 = 89.74%. Most ICC ECP specifications require ≥95% for structural fills.
5. The concept of "effective stress" in soil mechanics is most critical for predicting:
A) Soil color
B) Shear strength and settlement
C) Organic content
D) Soil pH
,Answer: B) Shear strength and settlement
Rationale: Effective stress (total stress minus pore water pressure) determines
intergranular friction and therefore shear strength. Settlement calculations rely on
effective stress changes. The ICC ECP exam emphasizes effective stress for foundation
design.
6. Which of the following soils would be most suitable for use as a select backfill behind
a retaining wall per ICC ECP recommendations?
A) High-plasticity clay (CH)
B) Uniform fine sand (SP)
C) Well-graded gravel with sand (GW-GM)
D) Organic silt (OH)
Answer: C) Well-graded gravel with sand (GW-GM)
Rationale: Free-draining granular soils with low plasticity reduce hydrostatic pressure on
retaining walls. CH and OH retain water; SP lacks gradation for stability. GW-GM
provides drainage and mechanical stability.
7. Using the Atterberg limits: Liquid Limit = 55, Plastic Limit = 25. The Plasticity Index is:
A) 20
B) 25
C) 30
D) 55
Answer: C) 30
Rationale: Plasticity Index (PI) = Liquid Limit - Plastic Limit = 55 - 25 = 30. PI indicates
soil plasticity range and is used in USCS classification.
8. A soil is classified as "CL" in USCS. This means:
A) Clayey sand with low plasticity
B) Low-plasticity clay of low compressibility
C) Silty clay with high plasticity
D) Organic clay
, Answer: B) Low-plasticity clay of low compressibility
Rationale: "C" = clay, "L" = low plasticity (LL < 50, PI ≈ 7-18). CL soils have moderate
shrink-swell potential and are common subgrade soils.
9. In standard Proctor compaction test (ASTM D698), the compactive effort is
approximately:
A) 12,400 ft-lbf/ft³
B) 20,000 ft-lbf/ft³
C) 56,000 ft-lbf/ft³
D) 70,000 ft-lbf/ft³
Answer: A) 12,400 ft-lbf/ft³
Rationale: Standard Proctor uses a 5.5 lb hammer falling 12 inches for 25 blows on 3
layers. Modified Proctor uses higher effort (56,250 ft-lbf/ft³). ICC ECP exam distinguishes
between these.
10. Field density test results show a wet density of 120 lb/ft³ and moisture content of
15%. The dry density is closest to:
A) 102 lb/ft³
B) 104 lb/ft³
C) 108 lb/ft³
D) 110 lb/ft³
Answer: B) 104 lb/ft³
Rationale: Dry density = wet density / (1 + w/100) = 120/(1.15) = 104.35 lb/ft³. Dry
density is required for percent compaction calculations.
11. Which of the following is NOT a typical use of a geotechnical report in plan review
per ICC ECP?
A) Determining bearing capacity for shallow foundations
B) Selecting appropriate stormwater pipe material color
C) Assessing lateral earth pressures on retaining walls
D) Evaluating settlement potential of compressible layers
