- What ACI-AGGREGATE-L1 Actually Tests
- Exam Format: Written and Performance Components
- The Eight Domains You Must Master
- Passing Standard and Retest Rules
- Registration, Workbook, and Fee Mechanics
- A Domain-Ordered Study Plan
- Calculator Rules and Performance-Exam Traps
- Who Hires ACI-AGGREGATE-L1 Technicians
- Frequently Asked Questions
- The written exam is open-book, two hours, roughly 100 multiple-choice questions using ACI-approved references only.
- You need 60% minimum on each required standard and 70% overall to pass the written component.
- The closed-book performance exam requires successful completion of every required procedure, not just verbal answers.
- Both the written and performance exams must be passed within one year of each other.
What ACI-AGGREGATE-L1 Actually Tests
Aggregate Testing Technician-Level 1, referred to internally by the American Concrete Institute (ACI) as ATT1, is a hands-on certification built around eight paired AASHTO/ASTM standards for sampling and testing mineral aggregates. It is not a theory-heavy academic exam. It is designed to confirm that a technician can correctly sample aggregate in the field, reduce that sample to a workable test portion, and then run the standard laboratory procedures used to characterize gradation, moisture, specific gravity, absorption, and organic impurities.
If you landed here searching for background on the credential itself before diving into study mechanics, our companion pieces on what ACI-AGGREGATE-L1 is, what the designation means, and what the acronym stands for cover the identity and scope in more depth. This guide focuses squarely on how to prepare for and pass both exam components on your first attempt.
Exam Format: Written and Performance Components
ACI-AGGREGATE-L1 certification is built from two separate exams, and you have to clear both to earn the credential:
- Written examination: Open-book, using ACI-approved references, with a two-hour time limit and approximately 100 multiple-choice questions.
- Performance examination: Closed-book. You must successfully complete every required procedure by hand, with verbal descriptions of steps permitted only where the standard allows it.
Testing is administered by approved sponsoring groups along with ACI examiners and proctors, and ACI does the grading. If you need to retake the written exam, eligible retests can also be scheduled through Prometric, which adds some scheduling flexibility compared to waiting for another in-person sponsor session.
For a deeper breakdown of exactly how scoring works on each half of the exam, see our dedicated article on the ACI-AGGREGATE-L1 passing score. And if you're still weighing how demanding this certification is relative to your background, our difficulty guide walks through the performance-exam expectations in more detail.
Key Takeaway
Because the written exam is open-book, memorizing standards word-for-word is less important than knowing exactly where each value, tolerance, and step lives in your CP-44 workbook so you can find it fast under a two-hour clock.
The Eight Domains You Must Master
Every ACI-AGGREGATE-L1 question and every performance-exam station traces back to one of eight paired AASHTO/ASTM standards. Get comfortable with each one individually before trying to cram them together - a full walkthrough of all eight lives in our exam domains guide, but here is the working list.
Domain 1: AASHTO R 90/ASTM D75 - Sampling of Aggregates
Covers how to obtain a representative field sample without introducing segregation or contamination bias.
- Correct sampling location and technique from stockpiles, belts, and transport units
Domain 2: AASHTO R 76/ASTM C702 - Reducing Samples of Aggregate to Testing Size
Focuses on mechanical splitting and quartering methods that shrink a field sample down to a lab-ready portion without skewing gradation.
- Splitter and quartering technique fidelity
Domain 3: AASHTO T 11/ASTM C117 - Materials Finer than 75-µm (No. 200) Sieve by Washing
Tests your ability to determine the percentage of fines lost through washing, a value that feeds directly into specification compliance.
- Washing endpoint judgment and drying sequence
Domain 4: AASHTO T 27/ASTM C136 - Sieve Analysis of Fine and Coarse Aggregates
The gradation workhorse standard; expect heavy emphasis on sieve stacking order, shaking duration, and percent-passing calculations.
- Cumulative retained vs. percent passing math
Domain 5: AASHTO T 85/ASTM C127 - Specific Gravity and Absorption of Coarse Aggregate
Requires precise saturated surface-dry (SSD) judgment and correct use of the wire basket/submersion method.
- SSD condition recognition by touch and visual cue
Domain 6: AASHTO T 84/ASTM C128 - Specific Gravity and Absorption of Fine Aggregate
The cone-and-tamp SSD test for fine aggregate, notoriously sensitive to technique and timing.
- Cone slump test for SSD confirmation
Domain 7: AASHTO T 255/ASTM C566 - Total Evaporable Moisture Content by Drying
A straightforward mass-loss-on-drying calculation, but one where rounding and unit errors cost easy points.
- Moisture content formula and sample mass handling
Domain 8: AASHTO T 21/ASTM C40 - Organic Impurities in Fine Aggregates
The color-comparison test for organic contamination, which relies on visual matching against a standard reference chart or solution.
- Reference color standard comparison procedure
Passing Standard and Retest Rules
ACI-AGGREGATE-L1's written exam has a two-part scoring rule that trips up candidates who only look at their overall percentage: you need at least 60% on each required standard individually, and at least 70% overall. That means you can't compensate for a weak domain by acing another one - every one of the eight domains has its own floor.
The performance exam works differently. There's no partial-credit percentage; you must successfully complete every required procedure, describing steps verbally only where the standard specifically permits it. Both the written and performance exams must be passed within one year of each other, and if you fail one, the retest covers the entire failed component - not just the parts you missed.
| Component | Format | Passing Standard |
|---|---|---|
| Written Exam | Open-book, 2-hour limit, ~100 multiple-choice questions | 60% minimum per standard, 70% overall |
| Performance Exam | Closed-book, hands-on procedures | Successful completion of every required procedure |
Registration, Workbook, and Fee Mechanics
Certification testing is administered through approved sponsoring groups along with ACI examiners and proctors, with ACI handling the grading. There are no education or work-experience prerequisites to register - anyone can sit for ACI-AGGREGATE-L1, which is one reason employers often use it as an entry-level field-lab credential. For the full eligibility picture, see our requirements breakdown.
The official study reference is CP-44, eighth edition, ACI's program workbook. Note that it includes the AASHTO standards rather than the ASTM texts - an important distinction if you're used to studying from ASTM documents. As of a September 10, 2026 check, ACI lists the workbook at $138 for non-members and $72 for ACI members.
Local sponsor pricing varies by chapter and session. As one dated example, Central Texas ACI's September 12, 2026 session in Pflugerville listed $675 for full certification, $475 for a written-only retest, and $525 for a performance-only retest, with the workbook priced separately and not included. These figures are specific to that sponsor and session - treat them as an illustration of what a local testing event might cost, not a national fee schedule. For a broader pricing discussion, see our certification cost breakdown, and for scheduling logistics, check exam dates and testing windows.
Key Takeaway
Budget for the CP-44 workbook and your sponsor's session fee separately - they are billed by two different entities (ACI and the local chapter), and workbook cost is typically excluded from the session price.
A Domain-Ordered Study Plan
Rather than studying the eight domains in random order, sequence your prep so that calculation-heavy standards come before judgment-heavy ones, since the latter benefit from hands-on repetition closer to your performance-exam date.
Sampling & Reduction Foundations
- Study Domain 1 (AASHTO R 90/ASTM D75) sampling technique
- Study Domain 2 (AASHTO R 76/ASTM C702) splitting and quartering
- Work through CP-44 sections covering both standards
Gradation and Washing Math
- Drill Domain 4 (AASHTO T 27/ASTM C136) percent-passing calculations
- Pair with Domain 3 (AASHTO T 11/ASTM C117) washing-loss calculations
- Practice with your approved simple-function calculator, not a phone
Specific Gravity and Moisture
- Practice SSD judgment for Domain 5 (AASHTO T 85/ASTM C127) and Domain 6 (AASHTO T 84/ASTM C128)
- Time yourself on Domain 7 (AASHTO T 255/ASTM C566) moisture calculations
- Review organic impurities color-matching for Domain 8 (AASHTO T 21/ASTM C40)
Full Simulation and Weak-Point Review
- Run full timed written practice under the two-hour limit
- Rehearse every performance procedure end to end, not just the ones you like
- Revisit any standard where you're under the 60% domain floor
This sequencing matters because the passing rule punishes any single weak domain, not just a weak overall average. If you consistently practice cumulative-style timed tests, our one-page cheat sheet and the practice exams on our main practice test platform are built around this same domain-by-domain breakdown so you can isolate weak spots before exam day.
Calculator Rules and Performance-Exam Traps
ACI permits approved simple-function, nonprogrammable calculators for the written exam. Mobile devices cannot be used as calculators, so don't plan on your phone as a backup - bring an actual approved calculator to the testing site.
On the performance side, one detail candidates frequently misread: the 30-minute limit applies per calculation worksheet, not to the entire performance examination as a whole. Each worksheet you complete during the performance test has its own 30-minute cap, which is a very different pacing reality than assuming you have one half-hour to finish everything. Plan your lab-station time accordingly, and don't panic if the whole performance session runs longer than 30 minutes - that's expected.
Who Hires ACI-AGGREGATE-L1 Technicians
Because ACI-AGGREGATE-L1 has no prerequisite education or experience requirement, it functions as an entry point into materials-testing lab work. Aggregate producers, ready-mix concrete suppliers, geotechnical and construction materials testing (CMT) labs, and public-agency quality-assurance programs commonly look for this credential when staffing field and lab technician roles that involve aggregate quality control. If you're evaluating whether this certification fits your career plans, our guides on ACI-AGGREGATE-L1 jobs, salary expectations, and whether the certification is worth it go deeper into market context than this study-focused article can.
Certification, once earned, lasts five years. Renewal requires passing both the written and performance examinations again - it is not a simple paperwork renewal, so keep your CP-44 workbook and notes rather than discarding them after your first pass.
Key Takeaway
Because renewal at the five-year mark requires retesting on both components, treat your first-attempt study materials as a long-term reference rather than disposable exam-week cramming notes.
Frequently Asked Questions
The written exam is open-book, but only ACI-approved references such as the CP-44 workbook are permitted. It has a two-hour time limit and roughly 100 multiple-choice questions. The performance exam, by contrast, is closed-book.
You need at least 60% on each required standard and at least 70% overall on the written exam. The performance exam requires successful completion of every required procedure rather than a percentage score. See our full passing score breakdown for more detail.
CP-44, eighth edition, includes the AASHTO standards rather than the ASTM texts, even though the eight domains are officially paired AASHTO/ASTM standard areas. Study from the AASHTO language since that's what's in your reference workbook.
Certification lasts five years. Renewal requires passing both the written and performance examinations again, not just an administrative renewal fee.
No. ACI permits approved simple-function, nonprogrammable calculators, but mobile devices cannot be used as calculators during the written exam.
Passing ACI-AGGREGATE-L1 on your first attempt comes down to respecting the exam's structure: study each of the eight domains until you clear the 60% floor individually, rehearse every performance procedure by hand rather than just reading about it, and keep your written and performance exam dates within the one-year window. For domain-by-domain practice questions modeled on this exact format, browse the tools available on the main practice test site.