- Why Sample Questions Are the Best Way to Audit Your Readiness
- Domain 1: Temperature Testing (ASTM C1064)
- Domain 2: Sampling Fresh Concrete (ASTM C172)
- Domain 3: Slump Testing (ASTM C143)
- Domain 4: Density, Yield, and Gravimetric Air Content (ASTM C138)
- Domain 5: Pressure Method Air Content (ASTM C231)
- Domain 6: Volumetric Air Content (ASTM C173)
- Domain 7: Making and Curing Specimens (ASTM C31)
- How the ACI Written Exam Frames These Questions
- Scheduling Your Domain Review Efficiently
- Frequently Asked Questions
- The ACI Concrete Field Testing Technician Grade I exam covers exactly seven ASTM domains - know every standard by number and letter suffix.
- Sample questions reveal the exam's precision: wrong thermometer placement, single-digit timing errors, or incorrect rod diameter can flip your answer.
- Domain 7 (ASTM C31) is the most procedurally complex - curing temperatures, striking-off sequence, and transport rules all appear in test questions.
- Both a written exam and a hands-on performance exam must be passed; sample questions primarily prepare you for the written portion.
Why Sample Questions Are the Best Way to Audit Your Readiness
Reading an ASTM standard is not the same as being tested on it. The ACI Concrete Field Testing Technician Grade I written exam is designed to distinguish candidates who have memorized general concepts from those who know the precise procedural details embedded in each of the seven ASTM standards. A question might ask about the maximum allowable time between obtaining the first and final portions of a composite sample - a number you will never guess correctly without having read ASTM C172 carefully.
Working through sample questions does something a passive read-through cannot: it forces retrieval, exposes gaps, and shows you exactly which type of procedural detail the exam rewards. This article walks through representative questions for each domain, explains why the correct answers are correct, and flags the specific ASTM language that trips up candidates most often.
Domain 1: Temperature Testing (ASTM C1064/C1064M)
ASTM C1064/C1064M - Temperature of Freshly Mixed Hydraulic-Cement Concrete
This domain tests your knowledge of the exact procedure for measuring concrete temperature in the field, including equipment requirements and time constraints.
- Minimum thermometer immersion depth and contact time with fresh concrete
- Acceptable temperature measurement range of the device
- Maximum elapsed time allowed from sampling to completing the temperature reading
- How to ensure the thermometer is not in contact with the container surface
Sample Question: When measuring the temperature of freshly mixed concrete in accordance with ASTM C1064, the thermometer must remain in the concrete for a minimum of how many minutes before the temperature is read?
Why this question matters: ASTM C1064 specifies a minimum immersion time. Candidates who remember only that "you stick a thermometer in" fail this question consistently. The standard also requires the sensing portion to be covered by at least 3 inches (75 mm) of concrete and that the reading be taken within 5 minutes of obtaining the sample. Every one of those numbers can appear on your exam.
Domain 2: Sampling Fresh Concrete (ASTM C172/C172M)
ASTM C172/C172M - Sampling Freshly Mixed Concrete
Sampling is the foundation of all other tests. Errors here invalidate every downstream result, which is why the exam treats this domain seriously.
- Minimum sample size required to perform standard tests
- Time window for obtaining a composite sample from a stationary or agitating mixer
- Portions to discard at the beginning and end of a discharge stream
- Maximum elapsed time from first to final increment when compositing
- Protection of the sample from sun, wind, and contamination before testing
Sample Question: According to ASTM C172, the composite sample of freshly mixed concrete should be obtained over a time period not to exceed:
A) 3 minutes B) 5 minutes C) 15 minutes D) 30 minutes
The correct answer is 15 minutes. Candidates who conflate this with the 5-minute window from C1064 choose B - one of the most common errors on the written exam. The standard also requires that sampling not begin until after the initial discharge has been discarded and that it not extend into the final portion of the load, details that appear as separate question stems.
Domain 3: Slump Testing (ASTM C143/C143M)
Slump is often the first test a technician performs in the field, and its apparent simplicity is deceptive. The ACI written exam finds precision errors that field technicians develop as bad habits over time.
ASTM C143/C143M - Slump of Hydraulic-Cement Concrete
Candidates must know not just how to perform the slump test but the exact tolerances, timing, and equipment specifications the standard requires.
- Dimensions of the slump cone (base, top, height)
- Number of layers and rods per layer during filling
- Maximum time from start of filling to lifting the cone
- How and where to measure the slump - and what constitutes a valid versus shear collapse
- Condition requirements for the base plate surface
Sample Question: During the slump test, each layer of concrete is rodded how many times with a 5/8-inch (16 mm) tamping rod?
The answer is 25 strokes, applied evenly over the cross-section. Questions may also ask about the penetration depth of the rod into the underlying layer (approximately 1 inch), the timing constraint for lifting the cone (raised in 5 ± 2 seconds), and what to do if a collapse occurs rather than a true slump. Each sub-procedure is fair game.
Domain 4: Density, Yield, and Gravimetric Air Content (ASTM C138/C138M)
ASTM C138/C138M - Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete
This domain introduces calculation-based questions. Understanding the formulas - not just the procedure - is essential.
- How to calculate density (unit weight) from mass and known container volume
- Yield calculation using the theoretical unit weight from mix design versus the measured unit weight
- Gravimetric air content formula and when this method is appropriate
- Calibration of the measure: determining the volume of the container
- Strike-off technique and the type of plate used
Sample Question: The air content of freshly mixed concrete can be determined gravimetrically using ASTM C138 when the theoretical unit weight from the mix design is known. If the measured unit weight is lower than the theoretical unit weight, what does that indicate?
It indicates a higher air content than designed, because air displaces heavier solid constituents and reduces overall density. The exam tests whether candidates understand the relationship between unit weight and air, not just the arithmetic. Be ready for questions that give you a measured density and ask you to calculate yield or relative yield.
Domain 5: Air Content by Pressure Method (ASTM C231/C231M)
ASTM C231 is one of the two methods used to measure air content directly, and it is the method most commonly specified on projects with normal-weight aggregates. The pressure meter - often called a Type B meter - has a distinctive operating procedure that the exam tests in detail.
ASTM C231/C231M - Air Content by the Pressure Method
- When the pressure method is not appropriate (lightweight or porous aggregates)
- Aggregate correction factor: what it is, how it is determined, and how it is applied
- Filling and consolidation procedure for the pressure bowl
- Operating sequence: pressurizing, stabilizing, and reading
- Type A versus Type B meter differences (conceptual awareness)
Sample Question: The aggregate correction factor used in ASTM C231 accounts for which of the following?
A) Moisture absorbed by the aggregate B) Air trapped within porous aggregate particles C) The compressibility of the cement paste D) Temperature differences between aggregate and mixing water
The answer is B. Porous aggregate particles absorb air pressure, leading to a falsely high air content reading if uncorrected. This concept is a high-frequency exam topic because it explains why the pressure method is restricted to normal-weight, relatively non-absorptive aggregates.
Domain 6: Air Content by Volumetric Method (ASTM C173/C173M)
ASTM C173/C173M - Air Content by the Volumetric Method
The volumetric method (Roll-A-Meter) is the preferred method for lightweight concrete or concrete made with air-entraining admixtures where the pressure method is unreliable.
- When to use volumetric over pressure method (aggregate type is the key criterion)
- How the meter works: displacing air with isopropyl alcohol
- Filling, rodding, and agitation sequence
- Reading the graduated neck and applying corrections
- Why this method is unaffected by aggregate porosity
Sample Question: Which liquid is added to the Roll-A-Meter during the volumetric air content test to displace entrapped and entrained air?
The answer is isopropyl alcohol. Candidates sometimes confuse this with water - a critical error. The alcohol prevents air from dissolving into the liquid, allowing it to be measured accurately in the graduated neck of the meter. Questions may also test the agitation procedure: rolling the meter while inverted a specified number of times before taking a reading.
Domain 7: Making and Curing Specimens (ASTM C31/C31M)
ASTM C31 is the most procedurally complex domain on the exam. It governs how cylinders and beams are made in the field, how they are initially cured, and how they are transported and stored before being delivered to a laboratory. Errors in specimen making directly affect compressive or flexural strength results - which is why this domain receives heavy emphasis in the written exam.
ASTM C31/C31M - Making and Curing Concrete Test Specimens in the Field
- Number of layers and rods per layer for cylinders of various sizes (4×8 in. vs. 6×12 in.)
- Internal vibration versus rodding: when each consolidation method is required based on slump
- Timing for initial curing: temperature range and maximum exposure duration before transport
- Protection of specimens from vibration and disturbance during the first 24 hours
- Standard curing versus field curing: different purposes, different procedures
- Striking-off and finishing the top surface of cylinders
- Maximum temperature and minimum temperature limits during initial curing period
Sample Question: According to ASTM C31, when the slump of the concrete is greater than 3 inches (75 mm), what consolidation method must be used for cylinder specimens?
The answer is rodding. Internal vibration is used when slump is 3 inches or less, or when specified. This is one of the most commonly reversed answers in practice tests - many candidates assume vibration is always superior and choose it incorrectly. The standard's slump threshold is the decision point, and it will appear on your exam.
Additional Sample Question: During the initial curing period, field-cured specimens must be maintained at a temperature between:
ASTM C31 specifies 60°F to 80°F (16°C to 27°C) for standard-cured specimens during the initial curing period. Field-cured specimens are maintained to represent actual structural conditions, so their temperature requirements differ. Understanding the distinction between standard curing (controlled lab conditions to evaluate mix potential) and field curing (representing in-place conditions) is essential for multi-part questions on this domain.
How the ACI Written Exam Frames These Questions
The ACI written exam uses multiple-choice questions that frequently present a scenario rather than a direct recall prompt. Instead of asking "What is the rod penetration depth during slump testing?" the question might read: "A technician rods the first layer of concrete during a slump test and notices the rod is not penetrating into the base. What should the technician do?" - testing procedural understanding, not just memorization.
| Question Type | Example Domain | What It Tests |
|---|---|---|
| Direct recall | C1064 (Temperature) | Specific number: immersion depth, time limit |
| Scenario / procedural | C31 (Specimens) | Correct sequence of actions under field conditions |
| Calculation | C138 (Density/Yield) | Apply formula using given values |
| Method selection | C231 vs. C173 (Air Content) | Identify correct test for given aggregate type |
| Error identification | C143 (Slump) | Recognize what a technician did wrong |
Reviewing the ACI Exam Day Checklist: What to Bring and Expect 2026 before your test date will help you understand the logistics of both the written and performance portions so you can allocate mental energy appropriately on the day itself.
Scheduling Your Domain Review Efficiently
Because the seven domains vary in complexity, a flat schedule that gives each equal time is less effective than a weighted approach. Below is a suggested framework. Adjust based on your hands-on experience - a technician who runs slump tests daily needs less time on C143 and more on C138 calculations.
Foundation: Sampling and Temperature (C172 + C1064)
- Read both standards in full; mark every number and time limit
- Complete 20-30 sample questions on each domain at concretefieldexam.com
- Write out sampling composite procedure from memory and check against the standard
Physical Tests: Slump and Density (C143 + C138)
- Focus on the dimensional specifications and layer/rod stroke counts
- Practice the yield and gravimetric air content calculations with invented numbers
- If possible, perform a physical slump test to reinforce procedural sequence
Air Content Methods: C231 + C173
- Build a comparison chart: when each method is used, what liquid/medium is involved, key limitations
- Memorize the aggregate correction factor concept for C231
- Run practice questions that present aggregate type scenarios and ask you to select the method
Specimen Making and Full Review (C31 + All Domains)
- C31 is the longest standard - allocate 3 study sessions to it alone
- Focus on: consolidation method selection by slump, curing temperature ranges, standard vs. field curing purpose
- Take a timed full-domain practice test and review every incorrect answer against the standard
Key Takeaway
When you miss a practice question, look up the exact clause in the ASTM standard - not just the answer key explanation. The exam tests the standard, so the standard is your primary study resource. Practice questions at concretefieldexam.com are written to reflect that level of specificity.
For a broader look at how this article fits into your overall preparation journey, see the companion piece ACI Practice Test: Sample Questions for All 7 Domains, which provides additional question sets and domain-by-domain breakdowns you can use alongside your standard review.
Frequently Asked Questions
It is technically possible to pass without reciting standard numbers verbatim, but the exam questions are written around ASTM procedural details. Knowing that "the slump test standard" requires 25 rod strokes per layer is the same knowledge whether you recall "C143" or not. That said, understanding which standard governs which test helps you cross-reference your notes and locate answers quickly if you review before test day.
ACI does not publicly publish an exact item count that remains static, and question counts can vary by administration. Focus on mastering all seven domains rather than engineering a minimum-question strategy. Thorough domain knowledge is more reliable than trying to predict how many questions cover each area.
Both are part of the seven-domain exam, so both will be tested. C231 (pressure method) applies to normal-weight, non-porous aggregates. C173 (volumetric method) is used when aggregate porosity would compromise pressure-method accuracy - typically lightweight concrete. Exam questions often present an aggregate description and ask you to select the correct method, so knowing this distinction is essential.
No. The Grade I exam covers field testing procedures only - the seven ASTM standards listed above. Mix design calculations, admixture chemistry, and structural design are outside the scope of this certification. If a question on a practice test drifts into those areas, it is not representative of the actual ACI written exam.
ACI's retake policy is managed through their certification office, and specific waiting periods or fees associated with retesting are best confirmed directly with ACI at the time of registration. Use any gap between attempts to work through the domains where your practice scores were weakest, and take full timed tests before rescheduling.
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