ACI Aggregate Testing Technician (ATT) Certification Exam — Questions and Answers

Question 1: How does risk management apply to daily practice in Aggregate Sampling & Reduction for ACI Aggregate Testing Technician professionals?

By avoiding high-risk situations entirely
Only through responding to incidents after they occur
Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)
Through annual safety audits exclusively

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

Effective risk management in Aggregate Sampling & Reduction requires proactive hazard identification and preventive measures, not just reactive responses. This approach reduces incidents, improves outcomes, and protects both professionals and clients.

Question 2: In aggregate quality evaluation, a fractured face count is most relevant for:

Silt content determination
Fine aggregate gradation
Organic impurity testing
Coarse aggregate used in asphalt mixtures (Correct answer)

Correct answer: Coarse aggregate used in asphalt mixtures

Fractured face counts are commonly specified for coarse aggregate in hot-mix asphalt to ensure adequate shear resistance and resistance to rutting.

Question 3: How does risk management apply to daily practice in Specific Gravity & Absorption for ACI Aggregate Testing Technician professionals?

Only through responding to incidents after they occur
Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)
Through annual safety audits exclusively
By avoiding high-risk situations entirely

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

Effective risk management in Specific Gravity & Absorption requires proactive hazard identification and preventive measures, not just reactive responses. This approach reduces incidents, improves outcomes, and protects both professionals and clients.

Question 4: What action should be taken if a field sample arrives at the laboratory with obvious segregation in the container?

Use only the top half of the material
Return the sample to the source for resampling
Test the segregated portions separately and average the results
Re-mix the entire container thoroughly before reducing the sample (Correct answer)

Correct answer: Re-mix the entire container thoroughly before reducing the sample

ASTM C702 requires thorough remixing before reduction to reintegrate any segregated particles and restore the sample's representativeness.

Question 5: In ASTM C123, lightweight particles are separated from aggregate by:

Magnetic separation
Acid dissolution
Heating to 100°C and measuring mass loss
Immersion in a heavy liquid of specified density (Correct answer)

Correct answer: Immersion in a heavy liquid of specified density

ASTM C123 uses a heavy liquid (such as zinc chloride solution) with a specific gravity between 1.95 and 2.0 to float out lightweight particles.

Question 6: In the clay lumps and friable particles test (ASTM C142), the sample is soaked in water for a period of:

12 ± 1 hours
24 ± 4 hours (Correct answer)
48 hours minimum
1 to 4 hours

Correct answer: 24 ± 4 hours

ASTM C142 requires soaking the sample in water for 24 ± 4 hours before attempting to break particles with the fingers.

Question 7: How does risk management apply to daily practice in Fine Aggregate Quality Tests for ACI Aggregate Testing Technician professionals?

Through annual safety audits exclusively
Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)
By avoiding high-risk situations entirely
Only through responding to incidents after they occur

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

Effective risk management in Fine Aggregate Quality Tests requires proactive hazard identification and preventive measures, not just reactive responses. This approach reduces incidents, improves outcomes, and protects both professionals and clients.

Question 8: If an aggregate fails the ASTM C40 color test, what is the recommended next step per the standard?

Retest after soaking the aggregate for 48 more hours
Wash the aggregate and retest immediately
Automatically reject the aggregate for all concrete use
Perform a mortar strength test per ASTM C87 (Correct answer)

Correct answer: Perform a mortar strength test per ASTM C87

A failing color result does not automatically disqualify the aggregate; ASTM C87 mortar strength testing can determine whether organic material actually harms concrete performance.

Question 9: A higher sand equivalent value in ASTM D2419 indicates:

More organic material
Cleaner aggregate with less clay contamination (Correct answer)
More clay and plastic fines present
Higher moisture content

Correct answer: Cleaner aggregate with less clay contamination

A higher sand equivalent value means a greater proportion of clean sand relative to clay fines, indicating better aggregate quality.

Question 10: What is the correct procedure when testing bulk density?

Use vacuum to settle particles
Fill using specified method such as rodding or shoveling (Correct answer)
Compact the sample with a rubber mallet
Fill the container randomly

Correct answer: Fill using specified method such as rodding or shoveling

The container must be filled in a standard manner—loose, rodded, or compacted—depending on the type of aggregate and test requirement.

Question 11: In Aggregate Sampling & Reduction, what is the FIRST step a ATT professional should take when encountering a new case or situation?

Conduct a comprehensive assessment and gather all relevant information (Correct answer)
Implement an immediate solution based on past experience
Consult with a supervisor before taking any action
Document the situation and wait for further instructions

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Aggregate Sampling & Reduction, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to ACI Aggregate Testing Technician practice.

Question 12: When a conflict arises between standard procedures and a unique situation in Organic Impurities Assessment, what should a ATT professional prioritize?

Strict adherence to written procedures without exception
The preference of the client or stakeholder
Safety and ethical obligations while seeking expert consultation (Correct answer)
The most cost-effective solution available

Correct answer: Safety and ethical obligations while seeking expert consultation

Safety and ethics always take priority in Organic Impurities Assessment. When standard procedures don't adequately address a unique situation, consulting with experienced colleagues or supervisors ensures both safety and professional standards are maintained.

Question 13: According to ASTM C33, the maximum allowable clay lumps and friable particles in fine aggregate for concrete is:

5.0%
3.0% (Correct answer)
1.0%
2.0%

Correct answer: 3.0%

ASTM C33 limits clay lumps and friable particles in fine aggregate to a maximum of 3.0% by mass.

Question 14: In the ASTM C40 test, to what level is the fine aggregate sample placed in the 12-oz prescription bottle?

The 4-1/2-oz level (Correct answer)
The 7-oz level
The 2-oz level
The 10-oz level

Correct answer: The 4-1/2-oz level

ASTM C40 requires fine aggregate to be added to the 4-1/2-oz (approximately 130 mL) level in the 12-oz glass prescription bottle.

Question 15: What is the maximum allowable material loss during sieve analysis per ASTM C136?

0.3% (Correct answer)
0.5%
1.0%
0.2%

Correct answer: 0.3%

Material loss should not exceed 0.3% of the original mass to ensure the accuracy of the test results.

Question 16: Which of the following best describes a 'composite sample' as defined in ASTM D75?

A single grab taken rapidly from a flowing stream
A sample taken from finished laboratory-prepared material
A sample made up of several increments combined together (Correct answer)
A sample taken from the highest point of a stockpile only

Correct answer: A sample made up of several increments combined together

A composite sample is formed by combining multiple individual increments collected from different points or times to represent a lot of material.

Question 17: For aggregate sampled from flowing streams (chutes or discharge points), the preferred device to collect the full width of material flow is:

A full-width sampling frame or pan that intercepts the entire stream (Correct answer)
A hand scoop inserted at the edge of the stream
A flat-bladed shovel
A core barrel driven vertically into the stream

Correct answer: A full-width sampling frame or pan that intercepts the entire stream

A sampling device that spans the full width of the flowing stream ensures all particle sizes are captured without size-biased collection.

Question 18: When sampling coarse aggregate from a stationary truck, what depth below the surface should increments be obtained?

Any depth is acceptable if spread evenly
From the exact center of the load by depth
From the top 50 mm only
At least 300 mm (12 in.) below the surface (Correct answer)

Correct answer: At least 300 mm (12 in.) below the surface

ASTM D75 requires digging at least 300 mm below the surface to avoid the biased, segregated layer at the top of the load.

Question 19: What is the PRIMARY purpose of continuing education requirements in Aggregate Sampling & Reduction for ATT professionals?

Fulfilling mandatory regulatory requirements only
Earning additional credentials for career advancement
Maintaining current knowledge and competency as the field evolves (Correct answer)
Networking with other professionals in the field

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Aggregate Sampling & Reduction ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the ACI Aggregate Testing Technician field.

Question 20: When quartering aggregate by hand, after dividing the sample into four equal parts, which portions are retained for the test sample?

Two opposite quadrants (Correct answer)
Any single quadrant
Three quadrants and one discarded
All four quadrants combined

Correct answer: Two opposite quadrants

Quartering retains two diagonally opposite quadrants, which together represent the original sample, while discarding the other two opposite quadrants.

Question 21: Which of the following situations represents 'biased sampling' of aggregate?

Taking increments at random intervals from a belt
Collecting samples from multiple truck loads
Consistently sampling only from the outside edges of a stockpile where fines accumulate (Correct answer)
Using a mechanical splitter to reduce the sample

Correct answer: Consistently sampling only from the outside edges of a stockpile where fines accumulate

Sampling from stockpile edges introduces bias because coarse particles roll away, leaving fines concentrated at the periphery, making the sample unrepresentative.

Question 22: Which environmental condition is most likely to affect the moisture content of a field sample between collection and testing?

Prolonged exposure to direct sunlight or wind in an open container (Correct answer)
Storing the sample in a sealed plastic bag
Placing the sample in a cooler without ice
Keeping the sample at room temperature indoors

Correct answer: Prolonged exposure to direct sunlight or wind in an open container

Open exposure to sun and wind causes evaporative drying that alters moisture content, potentially affecting absorption and unit weight tests.

Question 23: After washing, the retained aggregate must be dried to a constant mass at what temperature range?

150 ± 5°C (302 ± 9°F)
110 ± 5°C (230 ± 9°F) (Correct answer)
130 ± 5°C (266 ± 9°F)
90 ± 5°C (194 ± 9°F)

Correct answer: 110 ± 5°C (230 ± 9°F)

ASTM C117 specifies drying the washed sample to constant mass at 110 ± 5°C (230 ± 9°F), the standard oven-dry temperature for aggregates.

Question 24: What is the maximum allowable lightweight pieces (coal and lignite) in fine aggregate per ASTM C33 for concrete subject to surface wear?

1.5%
2.0%
1.0%
0.5% (Correct answer)

Correct answer: 0.5%

For fine aggregate in concrete subject to surface wear, ASTM C33 limits lightweight pieces (coal and lignite) to 0.5% by mass.

Question 25: In Organic Impurities Assessment, what is the FIRST step a ATT professional should take when encountering a new case or situation?

Document the situation and wait for further instructions
Conduct a comprehensive assessment and gather all relevant information (Correct answer)
Implement an immediate solution based on past experience
Consult with a supervisor before taking any action

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Organic Impurities Assessment, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to ACI Aggregate Testing Technician practice.

Question 26: What is the PRIMARY purpose of continuing education requirements in Moisture Content Testing for ATT professionals?

Fulfilling mandatory regulatory requirements only
Networking with other professionals in the field
Maintaining current knowledge and competency as the field evolves (Correct answer)
Earning additional credentials for career advancement

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Moisture Content Testing ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the ACI Aggregate Testing Technician field.

Question 27: Soft particles in coarse aggregate are a concern primarily because they:

Can crush under load and create voids that weaken concrete (Correct answer)
Improve freeze-thaw resistance
Reduce bleeding in fresh concrete
Increase the air content

Correct answer: Can crush under load and create voids that weaken concrete

Soft particles crush under compressive loads, creating voids and weak zones that significantly reduce concrete strength and durability.

Question 28: In Fine Aggregate Quality Tests, what is the FIRST step a ATT professional should take when encountering a new case or situation?

Conduct a comprehensive assessment and gather all relevant information (Correct answer)
Implement an immediate solution based on past experience
Document the situation and wait for further instructions
Consult with a supervisor before taking any action

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Fine Aggregate Quality Tests, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to ACI Aggregate Testing Technician practice.

Question 29: The required minimum mass of a field sample is primarily determined by which aggregate characteristic?

The delivery method (truck vs. belt)
The nominal maximum size of the aggregate (Correct answer)
The color of the aggregate
The source location of the aggregate

Correct answer: The nominal maximum size of the aggregate

ASTM D75 Table 1 ties minimum field sample mass directly to nominal maximum size because larger particles require more material to achieve statistical representativeness.

Question 30: In Specific Gravity & Absorption, what is the FIRST step a ATT professional should take when encountering a new case or situation?

Consult with a supervisor before taking any action
Conduct a comprehensive assessment and gather all relevant information (Correct answer)
Document the situation and wait for further instructions
Implement an immediate solution based on past experience

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Specific Gravity & Absorption, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to ACI Aggregate Testing Technician practice.

Question 31: After soaking in ASTM C142, how are clay lumps and friable particles identified?

By measuring density change
By attempting to crumble them between thumb and forefinger (Correct answer)
By color change
By sieve washing only

Correct answer: By attempting to crumble them between thumb and forefinger

Particles that can be broken down by rubbing between the thumb and forefinger after soaking are classified as clay lumps or friable particles.

Question 32: When sampling aggregates from a conveyor belt, how many approximately equal increments must be taken to constitute one sample according to ASTM D75?

At least 5 increments
A single large scoop
At least 3 increments (Correct answer)
At least 10 increments

Correct answer: At least 3 increments

ASTM D75 requires a minimum of three approximately equal increments taken from the full cross-section of the belt to constitute a field sample.

Question 33: What is the primary purpose of reducing a large field sample of aggregate to a smaller test sample?

To obtain a specimen of manageable size that still represents the field sample (Correct answer)
To remove oversized particles before testing
To dry the aggregate before shipping
To reduce transportation costs

Correct answer: To obtain a specimen of manageable size that still represents the field sample

Sample reduction produces a test specimen small enough for laboratory equipment while preserving the same particle size distribution as the original field sample.

Question 34: What does 'nominal maximum size' of an aggregate refer to in the context of sampling?

The sieve size equal to the maximum particle diameter
The largest sieve in the gradation set
The sieve size used to wash fine material
The smallest sieve that retains more than 10% of the material (Correct answer)

Correct answer: The smallest sieve that retains more than 10% of the material

Nominal maximum size is the smallest sieve opening through which the entire amount of aggregate is permitted to pass, retaining no more than 10% on that sieve.

Question 35: The rodding method in ASTM C29 is applicable for aggregates with a maximum particle size up to:

37.5 mm (1-1/2 in) (Correct answer)
50 mm (2 in)
25 mm (1 in)
19 mm (3/4 in)

Correct answer: 37.5 mm (1-1/2 in)

The rodding method applies to aggregate with a maximum particle size not exceeding 37.5 mm (1-1/2 in); larger sizes require the jigging method.

Question 36: When the field sample size exceeds what is needed but the technician has no mechanical splitter available, ASTM C702 recommends which alternative reduction method?

Sieve out all coarse particles until the required mass is achieved
Select the largest particles by hand to represent the full gradation
Use the quartering method as an approved alternative to mechanical splitting (Correct answer)
Randomly remove handfuls until the target mass is reached

Correct answer: Use the quartering method as an approved alternative to mechanical splitting

ASTM C702 explicitly recognizes quartering as an approved alternative when mechanical splitters are unavailable, provided the procedure is followed correctly.

Question 37: What is the purpose of determining specific gravity of aggregates?

To measure density and absorption (Correct answer)
To estimate compressive strength
To check gradation
To find aggregate color

Correct answer: To measure density and absorption

Specific gravity helps in concrete mix design and quality control by measuring the density of the aggregate.

Question 38: What is the PRIMARY purpose of continuing education requirements in Specific Gravity & Absorption for ATT professionals?

Earning additional credentials for career advancement
Maintaining current knowledge and competency as the field evolves (Correct answer)
Fulfilling mandatory regulatory requirements only
Networking with other professionals in the field

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Specific Gravity & Absorption ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the ACI Aggregate Testing Technician field.

Question 39: How is the percent passing a sieve calculated?

Sample weight minus retained weight divided by total sample weight, times 100. (Correct answer)
Retained weight divided by sample weight.
Sample weight times retained weight.
Retained weight minus sample weight.

Correct answer: Sample weight minus retained weight divided by total sample weight, times 100.

The percent passing is calculated by subtracting the cumulative retained weight from the total sample and dividing by the total, then multiplying by 100.

Question 40: Which standard of practice is MOST important for ensuring quality in Unit Weight & Voids Testing?

Strictly adhering to the same procedure in every situation
Using the most advanced technology available regardless of need
Following evidence-based protocols while adapting to specific circumstances (Correct answer)
Minimizing documentation to focus on practical work

Correct answer: Following evidence-based protocols while adapting to specific circumstances

Evidence-based protocols provide a foundation of proven practices, but effective ACI Aggregate Testing Technician professionals must also adapt their approach based on specific circumstances and individual case needs within Unit Weight & Voids Testing.

Question 41: During the ASTM C117 washing test, the aggregate is washed over which sieve to capture all fine material?

No. 50 (300 µm)
No. 100 (150 µm)
No. 200 (75 µm) (Correct answer)
No. 325 (45 µm)

Correct answer: No. 200 (75 µm)

The wash water and suspended fines pass through the No. 200 (75-µm) sieve, retaining only particles coarser than 75 µm.

Question 42: A particle classified as 'flat and elongated' in ASTM D4791 has a ratio of its maximum dimension to its minimum dimension exceeding:

2:1
1.5:1
5:1 (Correct answer)
3:1

Correct answer: 5:1

A particle is classified as flat and elongated in ASTM D4791 when the ratio of maximum to minimum dimension exceeds 5:1.

Question 43: Which standard of practice is MOST important for ensuring quality in Moisture Content Testing?

Minimizing documentation to focus on practical work
Following evidence-based protocols while adapting to specific circumstances (Correct answer)
Using the most advanced technology available regardless of need
Strictly adhering to the same procedure in every situation

Correct answer: Following evidence-based protocols while adapting to specific circumstances

Question 44: Which ASTM standard is used to determine lightweight pieces in aggregate (such as coal and lignite)?

ASTM C40
ASTM C127
ASTM C123 (Correct answer)
ASTM C142

Correct answer: ASTM C123

ASTM C123 is the standard test method for lightweight pieces in aggregate, used to identify coal, lignite, and other low-density particles.

Question 45: The percentage of material finer than the No. 200 sieve by washing is calculated using which formula?

(B − A) / B × 100
(A − B) / A × 100 (Correct answer)
(A + B) / A × 100
(A − B) / B × 100

Correct answer: (A − B) / A × 100

The formula (A − B) / A × 100 gives the percent passing No. 200, where A is the original dry mass and B is the dry mass after washing.

Question 46: What is the significance of bulk SSD specific gravity compared to bulk OD specific gravity in volumetric mix design?

SSD specific gravity is only relevant for lightweight aggregates
Both values are interchangeable and the choice does not affect results
OD specific gravity is always used because absorbed water evaporates during mixing
SSD specific gravity accounts for the volume of absorbed water within particles, more closely representing aggregate behavior in a saturated mix (Correct answer)

Correct answer: SSD specific gravity accounts for the volume of absorbed water within particles, more closely representing aggregate behavior in a saturated mix

SSD specific gravity includes the volume of absorbed water within permeable pores, representing aggregate volume as it behaves when fully saturated in a mix.

Question 47: What is the PRIMARY purpose of continuing education requirements in Soundness & Durability Testing for ATT professionals?

Earning additional credentials for career advancement
Networking with other professionals in the field
Maintaining current knowledge and competency as the field evolves (Correct answer)
Fulfilling mandatory regulatory requirements only

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Soundness & Durability Testing ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the ACI Aggregate Testing Technician field.

Question 48: Which ASTM standard covers the test method for clay lumps and friable particles in aggregates?

ASTM C117
ASTM C131
ASTM C136
ASTM C142 (Correct answer)

Correct answer: ASTM C142

ASTM C142 is the standard test method for clay lumps and friable particles in aggregates.

Question 49: When a conflict arises between standard procedures and a unique situation in Moisture Content Testing, what should a ATT professional prioritize?

Safety and ethical obligations while seeking expert consultation (Correct answer)
The preference of the client or stakeholder
The most cost-effective solution available
Strict adherence to written procedures without exception

Correct answer: Safety and ethical obligations while seeking expert consultation

Safety and ethics always take priority in Moisture Content Testing. When standard procedures don't adequately address a unique situation, consulting with experienced colleagues or supervisors ensures both safety and professional standards are maintained.

Question 50: Which of the following is NOT classified as a deleterious substance in aggregates per ASTM C33?

Chert of low specific gravity
Coal and lignite
Well-graded crushed granite (Correct answer)
Clay lumps

Correct answer: Well-graded crushed granite

Well-graded crushed granite is a sound, durable aggregate material and is not classified as a deleterious substance.

Question 51: If apparent specific gravity is 2.71 and bulk OD specific gravity is 2.61 for the same aggregate, what can be inferred?

The test was performed incorrectly
The aggregate contains no impermeable solids
The permeable pore volume is significant (Correct answer)
The aggregate is non-absorptive

Correct answer: The permeable pore volume is significant

A larger difference between apparent and bulk OD specific gravity indicates a greater permeable pore volume within the particles.

Question 52: The riffle splitter (mechanical sample splitter) divides a sample by:

Allowing fines to pass through while retaining coarse particles
Directing alternating chutes of material into two equal pans (Correct answer)
Separating material using a rotating drum
Separating material by particle density

Correct answer: Directing alternating chutes of material into two equal pans

A riffle splitter has an even number of chutes that alternate direction, splitting the stream into two roughly equal halves by mass.

Question 53: Which standard of practice is MOST important for ensuring quality in Los Angeles Abrasion Testing?

Strictly adhering to the same procedure in every situation
Minimizing documentation to focus on practical work
Using the most advanced technology available regardless of need
Following evidence-based protocols while adapting to specific circumstances (Correct answer)

Correct answer: Following evidence-based protocols while adapting to specific circumstances

Question 54: For a field sample taken from a truck or rail car, from how many locations within the load should increments be collected?

One central location
Two opposite corners only
The top center of the load only
At least five locations (Correct answer)

Correct answer: At least five locations

ASTM D75 specifies collecting increments from at least five locations distributed across the load to account for segregation that occurs during transport.

Question 55: When a conflict arises between standard procedures and a unique situation in Los Angeles Abrasion Testing, what should a ATT professional prioritize?

Strict adherence to written procedures without exception
The most cost-effective solution available
The preference of the client or stakeholder
Safety and ethical obligations while seeking expert consultation (Correct answer)

Correct answer: Safety and ethical obligations while seeking expert consultation

Safety and ethics always take priority in Los Angeles Abrasion Testing. When standard procedures don't adequately address a unique situation, consulting with experienced colleagues or supervisors ensures both safety and professional standards are maintained.

Question 56: Why is sampling aggregate directly from a stockpile surface considered a poor practice?

It damages the stockpile structure
Surface material is too dry to test
ASTM prohibits surface sampling entirely
Surface material has segregated and is not representative of the pile (Correct answer)

Correct answer: Surface material has segregated and is not representative of the pile

Segregation causes coarser particles to roll to the outer edges and base of a stockpile, making surface samples unrepresentative of the bulk material.

Question 57: Which type of material is primarily removed during the ASTM C117 washing procedure that could not be removed by dry sieving alone?

Clay coatings and silt adhering to larger particles (Correct answer)
Organic materials floating on the surface
Coarse particles bonded by cement
Oversized particles larger than 1.5 in.

Correct answer: Clay coatings and silt adhering to larger particles

The washing test removes clay coatings and silt that adhere to larger particles and cannot be separated by dry sieving alone.

Question 58: If the original oven-dry mass of a fine aggregate sample is 498 g and the oven-dry mass after washing is 485 g, what is the percentage of material finer than the No. 200 sieve?

2.8%
3.2%
2.0%
2.6% (Correct answer)

Correct answer: 2.6%

(498 − 485) / 498 × 100 = 13/498 × 100 = 2.61%, which rounds to 2.6%.

Question 59: In ASTM C117 (material finer than No. 200), after washing the aggregate is dried to constant mass at what temperature?

200 ± 5°C
60 ± 5°C
150 ± 5°C
110 ± 5°C (Correct answer)

Correct answer: 110 ± 5°C

After washing, the aggregate is dried to constant mass at 110 ± 5°C in accordance with ASTM C117.

Question 60: In the ASTM C29 jigging method, how many times is each side of the measure raised and dropped per layer?

75 times
25 times
100 times
50 times (Correct answer)

Correct answer: 50 times

The jigging method requires each side of the measure to be raised approximately 50 mm (2 in) and dropped 50 times per layer.

Question 61: What does the term 'apparent specific gravity' represent for aggregates?

Ratio of SSD mass to the mass of an equal volume of water
Ratio of dry mass to the total volume including surface moisture
Ratio of aggregate mass to the mass of an equal volume of water, excluding permeable pores (Correct answer)
Ratio of aggregate mass to the mass of an equal volume of water, including all pores

Correct answer: Ratio of aggregate mass to the mass of an equal volume of water, excluding permeable pores

Apparent specific gravity excludes permeable pore space, using only the impermeable solid volume.

Question 62: How does risk management apply to daily practice in Los Angeles Abrasion Testing for ACI Aggregate Testing Technician professionals?

Only through responding to incidents after they occur
By avoiding high-risk situations entirely
Through annual safety audits exclusively
Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

Effective risk management in Los Angeles Abrasion Testing requires proactive hazard identification and preventive measures, not just reactive responses. This approach reduces incidents, improves outcomes, and protects both professionals and clients.

Question 63: Per ASTM C33, what is the maximum allowable material finer than No. 200 sieve in fine aggregate for concrete subject to surface wear?

3.0% (Correct answer)
1.0%
5.0%
2.0%

Correct answer: 3.0%

ASTM C33 limits material finer than No. 200 in fine aggregate to 3.0% for concrete subject to abrasion.

Question 64: What is the PRIMARY purpose of continuing education requirements in Los Angeles Abrasion Testing for ATT professionals?

Earning additional credentials for career advancement
Networking with other professionals in the field
Fulfilling mandatory regulatory requirements only
Maintaining current knowledge and competency as the field evolves (Correct answer)

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Los Angeles Abrasion Testing ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the ACI Aggregate Testing Technician field.

Question 65: In ASTM D4791, what is the minimum number of particles required for a valid flat and elongated test?

500 particles
200 particles
100 particles (Correct answer)
50 particles

Correct answer: 100 particles

ASTM D4791 requires a minimum of 100 particles per size fraction to achieve statistically reliable results.

Question 66: When sampling from a stockpile, what is the most important principle to follow?

Collect from various depths and locations. (Correct answer)
Collect only from the top of the pile.
Take the sample from near the edges only.
Sample only dry areas.

Correct answer: Collect from various depths and locations.

Sampling from multiple locations and depths ensures the sample is representative of the entire stockpile.

Question 67: What documentation practice is considered essential in Los Angeles Abrasion Testing within the ACI Aggregate Testing Technician field?

Completing all documentation at the end of the workday
Recording actions, observations, and outcomes in real-time or as close to the event as possible (Correct answer)
Using shorthand notes that can be expanded later if needed
Only documenting unusual events or complications

Correct answer: Recording actions, observations, and outcomes in real-time or as close to the event as possible

Real-time or near-real-time documentation in Los Angeles Abrasion Testing ensures accuracy, provides a contemporaneous record, and is considered the gold standard for professional accountability and legal defensibility.

Question 68: When a sample of aggregate is transported to the laboratory, it should be stored in:

An open bucket for air drying
Any available container as long as it is labeled
A clean, sealed container that prevents contamination and moisture change (Correct answer)
A permeable burlap bag

Correct answer: A clean, sealed container that prevents contamination and moisture change

A sealed, clean container prevents contamination from foreign materials and preserves the in-situ moisture content until testing.

Question 69: Which ASTM standard provides the primary guidance for sampling aggregates from various sources including stockpiles, conveyor belts, and transportation units?

ASTM D75 (Correct answer)
ASTM C535
ASTM C136
ASTM C702

Correct answer: ASTM D75

ASTM D75 is the standard practice for sampling aggregates and covers procedures for obtaining samples from stockpiles, flowing streams, trucks, rail cars, and barges.

Question 70: When a conflict arises between standard procedures and a unique situation in Specific Gravity & Absorption, what should a ATT professional prioritize?

The most cost-effective solution available
The preference of the client or stakeholder
Strict adherence to written procedures without exception
Safety and ethical obligations while seeking expert consultation (Correct answer)

Correct answer: Safety and ethical obligations while seeking expert consultation

Safety and ethics always take priority in Specific Gravity & Absorption. When standard procedures don't adequately address a unique situation, consulting with experienced colleagues or supervisors ensures both safety and professional standards are maintained.

Question 71: What concentration of NaOH solution is used in the ASTM C40 organic impurities test?

3% by weight (Correct answer)
10% by weight
1% by weight
5% by weight

Correct answer: 3% by weight

ASTM C40 specifies a 3% sodium hydroxide (NaOH) solution by weight for detecting organic impurities in fine aggregate.

Question 72: An aggregate has a bulk SSD specific gravity of 2.62 and a bulk oven-dry specific gravity of 2.58. Which statement is correct?

The aggregate releases water on drying, so SSD < OD specific gravity is expected
The aggregate has zero absorption
The values indicate the aggregate is contaminated
The aggregate absorbs water, since SSD > OD specific gravity (Correct answer)

Correct answer: The aggregate absorbs water, since SSD > OD specific gravity

When SSD specific gravity exceeds OD specific gravity, the permeable pores hold absorbed water, which is typical for absorptive aggregates.

Question 73: When evaluating coarse aggregate shape for Portland cement concrete, the most significant concern with using highly elongated particles is:

They are prone to breaking during mixing and reduce the aggregate's effective size (Correct answer)
They reduce bleeding in fresh concrete
They increase the specific gravity of the mix
They improve the workability of the concrete mix

Correct answer: They are prone to breaking during mixing and reduce the aggregate's effective size

Highly elongated particles are fragile and tend to fracture during concrete mixing, reducing the effective aggregate size and potentially degrading concrete performance.

Question 74: What is the minimum sample size for a washing test on a fine aggregate (maximum size 3/8 in.) per ASTM C117?

500 g
200 g
300 g (Correct answer)
100 g

Correct answer: 300 g

ASTM C117 requires a minimum sample mass of 300 g for fine aggregate with a maximum size of 3/8 in.

Question 75: What is the purpose of washing aggregate over a No. 200 (75 µm) sieve per ASTM C117?

To remove material finer than 75 µm including clay and silt coatings (Correct answer)
To measure moisture content
To separate fine and coarse aggregate
To determine organic content

Correct answer: To remove material finer than 75 µm including clay and silt coatings

ASTM C117 washing removes clay, silt, and fine dust coatings finer than 75 µm that could weaken the paste-aggregate bond.

Question 76: How does risk management apply to daily practice in Soundness & Durability Testing for ACI Aggregate Testing Technician professionals?

Through annual safety audits exclusively
Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)
Only through responding to incidents after they occur
By avoiding high-risk situations entirely

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

Effective risk management in Soundness & Durability Testing requires proactive hazard identification and preventive measures, not just reactive responses. This approach reduces incidents, improves outcomes, and protects both professionals and clients.

Question 77: In Soundness & Durability Testing, what is the FIRST step a ATT professional should take when encountering a new case or situation?

Conduct a comprehensive assessment and gather all relevant information (Correct answer)
Consult with a supervisor before taking any action
Implement an immediate solution based on past experience
Document the situation and wait for further instructions

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Soundness & Durability Testing, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to ACI Aggregate Testing Technician practice.

Question 78: When testing for lightweight pieces per ASTM C123, the test result is expressed as:

Parts per million
Percentage by mass of lightweight pieces (Correct answer)
Number of particles per kilogram
Percentage by volume

Correct answer: Percentage by mass of lightweight pieces

ASTM C123 results are reported as the percentage by mass of lightweight pieces in the aggregate sample.

Question 79: Which equipment is essential for performing a mechanical sieve analysis?

Mechanical sieve shaker (Correct answer)
Oven
Moisture tester
Vacuum pump

Correct answer: Mechanical sieve shaker

A mechanical sieve shaker ensures consistent agitation of sieves for uniform separation of particle sizes.

Question 80: In Los Angeles Abrasion Testing, what is the FIRST step a ATT professional should take when encountering a new case or situation?

Implement an immediate solution based on past experience
Consult with a supervisor before taking any action
Conduct a comprehensive assessment and gather all relevant information (Correct answer)
Document the situation and wait for further instructions

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Los Angeles Abrasion Testing, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to ACI Aggregate Testing Technician practice.

Question 81: Which of the following is the most reliable method for obtaining a representative sample of fine aggregate from a stockpile?

Scooping from multiple surface locations on the pile
Sampling only from the pile center
Taking a single large sample from the pile base
Sampling from the flowing stream as material is loaded from the pile (Correct answer)

Correct answer: Sampling from the flowing stream as material is loaded from the pile

Sampling from the moving stream during loading captures material from throughout the stockpile and avoids surface segregation bias.

Question 82: Which ASTM standard covers the determination of bulk density of aggregates?

ASTM C29 (Correct answer)
ASTM C128
ASTM C117
ASTM C40

Correct answer: ASTM C29

ASTM C29 is the recognized method for measuring the bulk density and void content of aggregates.

Question 83: The term 'field sample' in ASTM D75 refers to:

A reduced sample prepared in the laboratory
The sample collected at the source before any reduction (Correct answer)
A sample taken directly from the field pavement
Any sample collected outside a controlled environment

Correct answer: The sample collected at the source before any reduction

The field sample is the total quantity of aggregate collected on-site from the source before it is reduced to individual test specimens.

Question 84: Which test best evaluates the presence of plastic fines (clay minerals) in fine aggregate that could reduce concrete durability?

Soundness test (ASTM C88)
Specific gravity test (ASTM C128)
Sand equivalent test (ASTM D2419) (Correct answer)
Los Angeles abrasion test

Correct answer: Sand equivalent test (ASTM D2419)

The sand equivalent test (ASTM D2419) is specifically designed to measure the relative proportion of clay-like plastic fines in fine aggregate.

Question 85: What does bulk density of aggregate refer to?

Volume of air in concrete
Volume of water displaced by aggregate
Mass per unit volume including voids (Correct answer)
Weight of aggregate particles only

Correct answer: Mass per unit volume including voids

Bulk density is the mass of aggregate required to fill a container of a specified unit volume and includes the volume of the particles and the voids between them.

Question 86: Which of the following is a valid sampling location for aggregate in transport?

Only from a moving belt conveyor.
From a stopped conveyor or truck bed. (Correct answer)
From the bottom of a wet stockpile.
From the front loader bucket.

Correct answer: From a stopped conveyor or truck bed.

Sampling from a stopped conveyor or transport vehicle ensures a more uniform and accessible sample.

Question 87: Which ASTM standard is used for sieve analysis of fine and coarse aggregates?

ASTM C29
ASTM C40
ASTM C117
ASTM C136/C136M (Correct answer)

Correct answer: ASTM C136/C136M

ASTM C136/C136M is the standard method used for determining the particle size distribution of aggregates through sieving.

Question 88: Which ASTM standard covers the test method for flat particles, elongated particles, or flat and elongated particles in coarse aggregate?

ASTM D4791 (Correct answer)
ASTM C142
ASTM C29
ASTM C131

Correct answer: ASTM D4791

ASTM D4791 is the standard test method for flat particles, elongated particles, or flat and elongated particles in coarse aggregate.

Question 89: What shape is the working end of the tamping rod specified in ASTM C29?

Hemispherical (Correct answer)
Pointed
Square
Flat and chisel-shaped

Correct answer: Hemispherical

ASTM C29 requires one end of the tamping rod to be hemispherical in shape to prevent breaking aggregate particles during compaction.

Question 90: What is the purpose of performing a sieve analysis on aggregates?

To remove fine particles.
To check aggregate temperature.
To determine particle size distribution. (Correct answer)
To identify moisture content.

Correct answer: To determine particle size distribution.

Sieve analysis helps determine the particle size distribution, which affects the workability and strength of concrete.

Question 91: Which deleterious substance in aggregate is most likely to cause unsightly staining and pop-outs in hardened concrete?

Crushed glass
Rounded quartz particles
Well-graded limestone fines
Coal and lignite particles (Correct answer)

Correct answer: Coal and lignite particles

Coal and lignite particles can expand, cause pop-outs, and produce dark staining on the surface of hardened concrete.

Question 92: During towel-drying of coarse aggregate to reach SSD, how can a technician confirm that SSD has been achieved?

The aggregate surface appears shiny and reflective
The aggregate shows a dull, surface-dry appearance with no free moisture film (Correct answer)
Individual particles no longer stick together when squeezed
The aggregate temperature equals ambient temperature

Correct answer: The aggregate shows a dull, surface-dry appearance with no free moisture film

SSD for coarse aggregate is indicated when the particles show a dull, matte surface with no visible free water film.

Question 93: Which type of aggregate coating is most harmful to concrete strength because it prevents proper bonding with cement paste?

Thin calcium carbonate dust
Clay and silt coatings (Correct answer)
Fine silica dust
Iron oxide surface film

Correct answer: Clay and silt coatings

Clay and silt coatings are most harmful because they create a weak interface that prevents cement paste from bonding to aggregate surfaces.

Question 94: Which ASTM standard governs the test for materials finer than the 75-µm (No. 200) sieve in mineral aggregates by washing?

ASTM C131
ASTM C136
ASTM C127
ASTM C117 (Correct answer)

Correct answer: ASTM C117

ASTM C117 is the standard test method for materials finer than 75-µm (No. 200) sieve in mineral aggregates by washing.

Question 95: What action is taken if air bubbles are observed in the pycnometer during the fine aggregate specific gravity test?

Heat the pycnometer to release trapped air faster
The test is immediately discarded
Agitate or roll the pycnometer to dislodge the air bubbles (Correct answer)
Add a surfactant to eliminate bubbles

Correct answer: Agitate or roll the pycnometer to dislodge the air bubbles

ASTM C128 requires agitating or rolling the pycnometer to remove entrapped air, which would otherwise cause low mass readings.

Question 96: In the ASTM C29 rodding method for bulk density, how many times is the tamping rod inserted per layer?

25 times (Correct answer)
10 times
50 times
15 times

Correct answer: 25 times

ASTM C29 requires the rod to be inserted 25 times per layer, distributing the strokes evenly over the surface.

Question 97: Why is it important to sample aggregate from a moving conveyor belt rather than from a stationary pile whenever possible?

Stationary piles are restricted areas under OSHA regulations
Belt samples have higher moisture content, making them easier to handle
Belt sampling is faster and requires less equipment
Moving belt samples capture the full cross-section of material flow, reducing segregation bias (Correct answer)

Correct answer: Moving belt samples capture the full cross-section of material flow, reducing segregation bias

Sampling from a moving belt captures the complete cross-section of aggregate being conveyed, avoiding the segregation bias inherent in stockpile sampling.

Question 98: When sampling aggregate from a flowing discharge stream, increments should be collected:

Only during peak flow velocity to capture the finest particles
From the fastest-moving center of the stream only
Only during the first 10% and last 10% of the discharge
At regular time intervals throughout the entire discharge period (Correct answer)

Correct answer: At regular time intervals throughout the entire discharge period

Collecting increments at regular intervals throughout the entire discharge period ensures that material from all phases of the discharge is represented in the composite sample.

Question 99: What is the proper procedure if material is retained on the sieve frame edge?

Report it as passing.
Discard the retained material.
Push material through the mesh.
Return it to the sieve for proper separation. (Correct answer)

Correct answer: Return it to the sieve for proper separation.

Aggregates caught on the sieve frame edge should be moved back into the sieve to ensure accurate mass distribution results.

Question 100: Aggregate sampling plans should be developed with input from which parties?

Only the aggregate producer
Only the project owner and contractor
Only the testing laboratory
All parties involved in the project including purchaser, producer, and testing laboratory (Correct answer)

Correct answer: All parties involved in the project including purchaser, producer, and testing laboratory

ASTM D75 recommends that sampling plans be developed cooperatively among all stakeholders to ensure the plan meets project acceptance requirements.

ACI Aggregate Testing Technician (ATT) Certification Exam

The ACI Aggregate Testing Technician certification validates competency in performing ASTM and AASHTO aggregate sampling, gradation, and physical property tests on fine and coarse aggregates used in concrete and construction materials.

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35 min

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70%

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