ACI Concrete Construction Special Inspector Standards Final
Exam Questions and Answers 100% Correct | Updated
Question 1
According to ACI 117-10, the specified tolerance for the variation in the vertical alignment of a
column from a 20-foot length is:
A) +/- 1/8 inch
B) +/- 1/4 inch
C) +/- 3/8 inch
D) +/- 1/2 inch
E) +/- 1 inch
Correct Answer: B) +/- 1/4 inch
Rationale: ACI 117-10, "Standard Specification for Tolerances for Concrete Construction
and Materials," provides specific allowable deviations. For vertical elements like columns,
the standard tolerance for vertical alignment over a 20-foot length is typically +/- 1/4 inch,
ensuring the structure is built as designed without significant eccentricity.
Question 2
As per ACI 301-16 (Specification for Structural Concrete), what is the required action if concrete
is not placed within 90 minutes after the start of mixing?
A) Add water to restore the slump.
B) Reject the concrete.
C) Add a high-range water-reducing admixture.
D) Continue placement if the slump is still within tolerance.
E) Retest the air content before placement.
Correct Answer: B) Reject the concrete.
Rationale: ACI 301-16 sets a standard time limit for placing concrete to ensure its
properties are not compromised by excessive hydration and setting. Unless a shorter or
longer time is specified, concrete must be discharged and placed within 90 minutes. After
this time, the concrete must be rejected as its workability and long-term properties can no
longer be guaranteed.
Question 3
Based on ACI 318-14, what is the primary purpose of providing concrete cover over reinforcing
steel?
A) To ensure proper consolidation of the concrete.
B) To protect the reinforcement from corrosion and fire.
C) To increase the overall weight of the member.
D) To make it easier to place the concrete.
E) To prevent the reinforcement from shifting during placement.
Correct Answer: B) To protect the reinforcement from corrosion and fire.
Rationale: ACI 318-14, "Building Code Requirements for Structural Concrete," specifies
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minimum concrete cover for reinforcement. This cover acts as a protective barrier,
preventing moisture and chlorides from reaching the steel and causing corrosion. It also
serves as an insulating layer that protects the steel from losing its strength during a fire.
Question 4
In accordance with ACI 305R-10 (Hot Weather Concreting), which condition is most likely to
cause the formation of plastic shrinkage cracks?
A) Low concrete temperature and high humidity.
B) High wind speed and low humidity.
C) Low ambient temperature and low wind speed.
D) High humidity and no direct sunlight.
E) Using a water-reducing admixture.
Correct Answer: B) High wind speed and low humidity.
Rationale: ACI 305R-10 explains that plastic shrinkage cracks occur when the rate of
evaporation of surface moisture exceeds the rate at which bleed water rises to the surface.
Conditions that increase evaporation, such as high wind speed, low humidity, and high
temperatures, create the greatest risk for this type of cracking.
Question 5
According to ACI 306R-10 (Cold Weather Concreting), what is the minimum temperature at
which freshly placed concrete must be protected from freezing?
A) 32°F (0°C)
B) 40°F (4°C)
C) 50°F (10°C)
D) 55°F (13°C)
E) 60°F (16°C)
Correct Answer: C) 50°F (10°C)
Rationale: ACI 306R-10 defines cold weather as a period when the average daily air
temperature is less than 40°F for more than 3 successive days. It recommends that concrete
be maintained at a temperature of at least 50°F for a specified period to ensure it gains
sufficient strength to resist the effects of freezing. Freezing of fresh concrete can reduce its
ultimate strength by up to 50%.
Question 6
A Special Inspector is observing the consolidation of concrete in a deep wall form. According to
ACI 309R-05 (Guide for Consolidation), how should an internal vibrator be inserted?
A) At a 45-degree angle to the form face.
B) Horizontally into the side of the lift.
C) Nearly vertical, allowing it to penetrate the previous lift.
D) Slowly, to avoid disturbing the aggregate.
E) Only in the center of the placement, away from the reinforcement.
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Correct Answer: C) Nearly vertical, allowing it to penetrate the previous lift.
Rationale: ACI 309R-05 states that internal vibrators should be inserted vertically to the
full depth of the lift and should penetrate the upper portion of the preceding lift by several
inches. This action ensures a monolithic bond between the two layers and prevents the
formation of a cold joint.
Question 7
As described in ACI 308R-01 (Guide to Curing Concrete), what is the primary purpose of
curing?
A) To cool the concrete surface rapidly.
B) To provide a smooth and uniform surface finish.
C) To maintain a satisfactory moisture content and temperature for hydration.
D) To accelerate the setting time of the concrete.
E) To prevent the formwork from sticking to the concrete.
Correct Answer: C) To maintain a satisfactory moisture content and temperature for
hydration.
Rationale: Curing is one of the most critical steps in concrete construction. ACI 308R-01
explains that its purpose is to maintain adequate moisture and a favorable temperature in
the concrete for a sufficient period. This allows the cement hydration process to continue,
enabling the concrete to achieve its desired strength and durability.
Question 8
Per the International Building Code (IBC) Chapter 19, when is a Special Inspector required to
perform continuous inspection of concrete placement?
A) For all concrete placements, regardless of strength.
B) Only for concrete with a specified compressive strength less than 2,500 psi.
C) For concrete with a specified compressive strength greater than 5,000 psi.
D) Only when shotcrete is being used.
E) Whenever lightweight concrete is placed.
Correct Answer: C) For concrete with a specified compressive strength greater than 5,000
psi.
Rationale: The IBC specifies conditions that require special inspection. Chapter 19 requires
continuous special inspection during the placement of structural concrete with a specified
compressive strength, f'c, in excess of 5,000 psi. This is due to the higher quality control
demands for high-strength concrete.
Question 9
According to ACI 347-14 (Guide to Formwork for Concrete), what is the primary function of
form ties?
A) To align the forms vertically.
B) To provide a surface for attaching architectural finishes.
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C) To resist the lateral pressure of the fresh concrete.
D) To serve as a guide for screeding the concrete surface.
E) To provide spacing for reinforcing steel.
Correct Answer: C) To resist the lateral pressure of the fresh concrete.
Rationale: ACI 347-14 details the design and construction of formwork. Form ties are
tensile units designed to hold concrete forms together at a specific spacing. Their primary
purpose is to withstand the significant outward lateral pressure exerted by the fluid
concrete, preventing the forms from spreading apart.
Question 10
A contractor is using a pumping method to place concrete for a large slab. ACI 304.2R-96
indicates that a potential issue with pumping is segregation. What is "slugging" in this context?
A) The slow movement of concrete through the pump line.
B) The complete blockage of the pump line.
C) The separation of coarse aggregate from the mortar at the discharge end.
D) The intermittent spurting of concrete from the discharge hose.
E) The addition of extra water at the pump hopper.
Correct Answer: D) The intermittent spurting of concrete from the discharge hose.
Rationale: ACI 304.2R-96 (Placing Concrete by Pumping Methods) describes slugging as
the pulsating or intermittent flow of concrete from the end of the discharge line. This is
often caused by a breakdown in the continuous flow of material, sometimes due to gaps in
the mix or air pockets, and can lead to segregation.
Question 11
The Manual of Concrete Inspection (MNL-2) states that a slump test is a measure of the
concrete's:
A) Compressive strength
B) Air content
C) Consistency
D) Unit weight
E) Temperature
Correct Answer: C) Consistency
Rationale: The slump test (ASTM C143) is a field test used to measure the consistency or
workability of freshly mixed concrete. It provides an indication of the uniformity of the
concrete from batch to batch but is not a direct measure of its strength, air content, or
other properties.
Question 12
According to ACI 213R-14 (Guide for Structural Lightweight-Aggregate Concrete), how does
the density of structural lightweight concrete compare to normal-weight concrete?
Exam Questions and Answers 100% Correct | Updated
Question 1
According to ACI 117-10, the specified tolerance for the variation in the vertical alignment of a
column from a 20-foot length is:
A) +/- 1/8 inch
B) +/- 1/4 inch
C) +/- 3/8 inch
D) +/- 1/2 inch
E) +/- 1 inch
Correct Answer: B) +/- 1/4 inch
Rationale: ACI 117-10, "Standard Specification for Tolerances for Concrete Construction
and Materials," provides specific allowable deviations. For vertical elements like columns,
the standard tolerance for vertical alignment over a 20-foot length is typically +/- 1/4 inch,
ensuring the structure is built as designed without significant eccentricity.
Question 2
As per ACI 301-16 (Specification for Structural Concrete), what is the required action if concrete
is not placed within 90 minutes after the start of mixing?
A) Add water to restore the slump.
B) Reject the concrete.
C) Add a high-range water-reducing admixture.
D) Continue placement if the slump is still within tolerance.
E) Retest the air content before placement.
Correct Answer: B) Reject the concrete.
Rationale: ACI 301-16 sets a standard time limit for placing concrete to ensure its
properties are not compromised by excessive hydration and setting. Unless a shorter or
longer time is specified, concrete must be discharged and placed within 90 minutes. After
this time, the concrete must be rejected as its workability and long-term properties can no
longer be guaranteed.
Question 3
Based on ACI 318-14, what is the primary purpose of providing concrete cover over reinforcing
steel?
A) To ensure proper consolidation of the concrete.
B) To protect the reinforcement from corrosion and fire.
C) To increase the overall weight of the member.
D) To make it easier to place the concrete.
E) To prevent the reinforcement from shifting during placement.
Correct Answer: B) To protect the reinforcement from corrosion and fire.
Rationale: ACI 318-14, "Building Code Requirements for Structural Concrete," specifies
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minimum concrete cover for reinforcement. This cover acts as a protective barrier,
preventing moisture and chlorides from reaching the steel and causing corrosion. It also
serves as an insulating layer that protects the steel from losing its strength during a fire.
Question 4
In accordance with ACI 305R-10 (Hot Weather Concreting), which condition is most likely to
cause the formation of plastic shrinkage cracks?
A) Low concrete temperature and high humidity.
B) High wind speed and low humidity.
C) Low ambient temperature and low wind speed.
D) High humidity and no direct sunlight.
E) Using a water-reducing admixture.
Correct Answer: B) High wind speed and low humidity.
Rationale: ACI 305R-10 explains that plastic shrinkage cracks occur when the rate of
evaporation of surface moisture exceeds the rate at which bleed water rises to the surface.
Conditions that increase evaporation, such as high wind speed, low humidity, and high
temperatures, create the greatest risk for this type of cracking.
Question 5
According to ACI 306R-10 (Cold Weather Concreting), what is the minimum temperature at
which freshly placed concrete must be protected from freezing?
A) 32°F (0°C)
B) 40°F (4°C)
C) 50°F (10°C)
D) 55°F (13°C)
E) 60°F (16°C)
Correct Answer: C) 50°F (10°C)
Rationale: ACI 306R-10 defines cold weather as a period when the average daily air
temperature is less than 40°F for more than 3 successive days. It recommends that concrete
be maintained at a temperature of at least 50°F for a specified period to ensure it gains
sufficient strength to resist the effects of freezing. Freezing of fresh concrete can reduce its
ultimate strength by up to 50%.
Question 6
A Special Inspector is observing the consolidation of concrete in a deep wall form. According to
ACI 309R-05 (Guide for Consolidation), how should an internal vibrator be inserted?
A) At a 45-degree angle to the form face.
B) Horizontally into the side of the lift.
C) Nearly vertical, allowing it to penetrate the previous lift.
D) Slowly, to avoid disturbing the aggregate.
E) Only in the center of the placement, away from the reinforcement.
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Correct Answer: C) Nearly vertical, allowing it to penetrate the previous lift.
Rationale: ACI 309R-05 states that internal vibrators should be inserted vertically to the
full depth of the lift and should penetrate the upper portion of the preceding lift by several
inches. This action ensures a monolithic bond between the two layers and prevents the
formation of a cold joint.
Question 7
As described in ACI 308R-01 (Guide to Curing Concrete), what is the primary purpose of
curing?
A) To cool the concrete surface rapidly.
B) To provide a smooth and uniform surface finish.
C) To maintain a satisfactory moisture content and temperature for hydration.
D) To accelerate the setting time of the concrete.
E) To prevent the formwork from sticking to the concrete.
Correct Answer: C) To maintain a satisfactory moisture content and temperature for
hydration.
Rationale: Curing is one of the most critical steps in concrete construction. ACI 308R-01
explains that its purpose is to maintain adequate moisture and a favorable temperature in
the concrete for a sufficient period. This allows the cement hydration process to continue,
enabling the concrete to achieve its desired strength and durability.
Question 8
Per the International Building Code (IBC) Chapter 19, when is a Special Inspector required to
perform continuous inspection of concrete placement?
A) For all concrete placements, regardless of strength.
B) Only for concrete with a specified compressive strength less than 2,500 psi.
C) For concrete with a specified compressive strength greater than 5,000 psi.
D) Only when shotcrete is being used.
E) Whenever lightweight concrete is placed.
Correct Answer: C) For concrete with a specified compressive strength greater than 5,000
psi.
Rationale: The IBC specifies conditions that require special inspection. Chapter 19 requires
continuous special inspection during the placement of structural concrete with a specified
compressive strength, f'c, in excess of 5,000 psi. This is due to the higher quality control
demands for high-strength concrete.
Question 9
According to ACI 347-14 (Guide to Formwork for Concrete), what is the primary function of
form ties?
A) To align the forms vertically.
B) To provide a surface for attaching architectural finishes.
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C) To resist the lateral pressure of the fresh concrete.
D) To serve as a guide for screeding the concrete surface.
E) To provide spacing for reinforcing steel.
Correct Answer: C) To resist the lateral pressure of the fresh concrete.
Rationale: ACI 347-14 details the design and construction of formwork. Form ties are
tensile units designed to hold concrete forms together at a specific spacing. Their primary
purpose is to withstand the significant outward lateral pressure exerted by the fluid
concrete, preventing the forms from spreading apart.
Question 10
A contractor is using a pumping method to place concrete for a large slab. ACI 304.2R-96
indicates that a potential issue with pumping is segregation. What is "slugging" in this context?
A) The slow movement of concrete through the pump line.
B) The complete blockage of the pump line.
C) The separation of coarse aggregate from the mortar at the discharge end.
D) The intermittent spurting of concrete from the discharge hose.
E) The addition of extra water at the pump hopper.
Correct Answer: D) The intermittent spurting of concrete from the discharge hose.
Rationale: ACI 304.2R-96 (Placing Concrete by Pumping Methods) describes slugging as
the pulsating or intermittent flow of concrete from the end of the discharge line. This is
often caused by a breakdown in the continuous flow of material, sometimes due to gaps in
the mix or air pockets, and can lead to segregation.
Question 11
The Manual of Concrete Inspection (MNL-2) states that a slump test is a measure of the
concrete's:
A) Compressive strength
B) Air content
C) Consistency
D) Unit weight
E) Temperature
Correct Answer: C) Consistency
Rationale: The slump test (ASTM C143) is a field test used to measure the consistency or
workability of freshly mixed concrete. It provides an indication of the uniformity of the
concrete from batch to batch but is not a direct measure of its strength, air content, or
other properties.
Question 12
According to ACI 213R-14 (Guide for Structural Lightweight-Aggregate Concrete), how does
the density of structural lightweight concrete compare to normal-weight concrete?
