- What ACI-AGGREGATE-L1 Actually Is
- Who Administers the Certification
- Eligibility: No Prerequisites Required
- Exam Structure: Written + Performance
- The Eight Domains You Must Master
- CP-44 Workbook and Approved References
- Fees and Registration Mechanics
- Scheduling Your Prep by Domain
- Who Hires Aggregate Testing Technicians
- Certification Validity and Renewal
- Frequently Asked Questions
- ACI-AGGREGATE-L1 is administered by the American Concrete Institute, internally referenced as ATT1.
- The written exam is open-book, two hours, roughly 100 multiple-choice questions.
- You need at least 60% on each required standard and 70% overall to pass the written portion.
- A separate closed-book performance exam requires successfully completing every required procedure.
What ACI-AGGREGATE-L1 Actually Is
ACI-AGGREGATE-L1 is the site key used for the American Concrete Institute's Aggregate Testing Technician-Level 1 certification, internally abbreviated ATT1 in ACI's own program materials. It is a credential built specifically around the sampling and testing of aggregate materials - the sand, gravel, and crushed stone that go into concrete and asphalt mixes. If you've landed here searching for what this designation means, the short answer is: it verifies that a person can correctly sample aggregate in the field and run the standard laboratory tests used to characterize that aggregate, following AASHTO and ASTM procedures side by side.
This is not a generic "quality control" title. It is tied to eight specific paired standards, a defined written examination, and a hands-on performance examination. For a broader breakdown of what the letters mean and how the program is structured, see ACI-AGGREGATE-L1 Meaning and What Does ACI-AGGREGATE-L1 Stand For?.
Who Administers the Certification
Certification testing is administered by approved sponsoring groups working with ACI examiners and proctors. ACI itself handles grading. If you fail a written component and need to retest, eligible retests can also be scheduled through Prometric testing centers rather than exclusively through a local sponsoring group's session. This dual pathway matters for planning - your first attempt is typically tied to a sponsor's scheduled session, but a retest doesn't necessarily require waiting for another full local offering.
Policy governing the program, CPP 620.3-25, was most recently revised May 16, 2025. The underlying job-task analysis that defines what the exam covers was approved September 21, 2020, with editorial corrections made October 19, 2021. That job-task analysis is what ultimately drives the eight domains covered below.
Eligibility: No Prerequisites Required
There are no specific education or work-experience prerequisites to sit for ACI-AGGREGATE-L1. This is a meaningful detail for anyone comparing certifications - you don't need a degree, a minimum number of years in a materials lab, or a sponsoring employer letter to register. Anyone can enroll in an approved session and attempt both the written and performance components.
That said, "no prerequisites" doesn't mean "no preparation needed." The exam assumes familiarity with laboratory procedure, sieve work, and basic calculations. For a fuller discussion of what "no prerequisites" really means in practice, read ACI-AGGREGATE-L1 Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Exam Structure: Written + Performance
ACI-AGGREGATE-L1 certification requires passing two distinct components, and both matter equally for earning the credential.
The Written Examination
- Open-book, using ACI-approved references only
- Two-hour time limit
- Approximately 100 multiple-choice questions
- Passing requires at least 60% on each required standard AND 70% overall
The dual-threshold scoring is one of the most misunderstood parts of this exam. Scoring 70% overall isn't sufficient if you badly fail one individual standard - you must clear the 60% floor on each of the required standards separately. This is explained in more depth in ACI-AGGREGATE-L1 Passing Score 2026: Exactly What You Need to Pass.
The Performance Examination
The performance exam is closed-book and requires successfully completing every required procedure by hand - physically sampling, splitting, sieving, and testing aggregate under observation. Verbal descriptions of a step are only accepted where the program specifically permits them; otherwise you must physically demonstrate the procedure. Performance calculation worksheets carry a maximum limit of 30 minutes each - this is a per-worksheet cap, not a single 30-minute limit for the entire performance exam, which is a distinction candidates frequently misread.
Key Takeaway
Both the written and performance components must be passed within one year of each other. If you pass one and fail (or delay) the other beyond that window, you may need to retake the expired component. A retest always covers the entire failed component - not just the questions or steps you missed.
Calculators
Approved simple-function, nonprogrammable calculators are permitted during testing. Mobile phones - even in calculator mode - cannot be used. Bring a dedicated device.
The Eight Domains You Must Master
ACI-AGGREGATE-L1's content is organized around eight paired AASHTO/ASTM standard areas. These are the official domains recognized by the program, and every exam question and every performance task traces back to one of them.
Domain 1: AASHTO R 90 / ASTM D75 - Sampling of Aggregates
Covers correct field sampling technique, including how sample location and method affect representativeness.
- Understand minimum sample sizes and sampling from different source types (stockpile, belt, transport unit)
Domain 2: AASHTO R 76 / ASTM C702 - Reducing Samples to Testing Size
Covers splitting large field samples down to a testing-appropriate quantity without introducing bias.
- Know the mechanical splitter and quartering methods and when each is appropriate
Domain 3: AASHTO T 11 / ASTM C117 - Materials Finer than 75-µm Sieve by Washing
Covers determining the percentage of material passing the No. 200 sieve using a wash procedure.
- Understand drying, washing, and mass-loss calculation sequencing
Domain 4: AASHTO T 27 / ASTM C136 - Sieve Analysis of Fine and Coarse Aggregates
Covers full gradation testing across a nested sieve stack for both fine and coarse aggregate.
- Be fluent in cumulative percent retained/passing calculations
Domain 5: AASHTO T 85 / ASTM C127 - Specific Gravity and Absorption of Coarse Aggregate
Covers bulk specific gravity, bulk SG (SSD), apparent specific gravity, and absorption for coarse material.
- Know the saturated surface-dry (SSD) condition and how it's identified for coarse aggregate
Domain 6: AASHTO T 84 / ASTM C128 - Specific Gravity and Absorption of Fine Aggregate
Covers the same specific gravity and absorption concepts as Domain 5, applied to fine aggregate using the cone-slump SSD check.
- Master the cone test for confirming SSD condition in fine aggregate
Domain 7: AASHTO T 255 / ASTM C566 - Total Evaporable Moisture Content by Drying
Covers determining moisture content of an aggregate sample through oven drying and mass comparison.
- Understand the difference between total moisture and absorbed moisture
Domain 8: AASHTO T 21 / ASTM C40 - Organic Impurities in Fine Aggregates
Covers the colorimetric test used to flag potentially harmful organic material in fine aggregate for concrete.
- Know the standard color plate comparison procedure and its limitations
For a domain-by-domain study breakdown with more detail on subtopics and calculation types, see ACI-AGGREGATE-L1 Exam Domains 2026: Complete Guide to All 8 Content Areas.
CP-44 Workbook and Approved References
The program's official workbook is CP-44, eighth edition. Unlike some other ACI workbooks, CP-44 includes the actual AASHTO standard texts rather than the ASTM versions - an important detail if you've been studying from ASTM documents and assumed the terminology would match exactly. ACI's own store listing prices the workbook at $138 for non-members and $72 for members (checked September 10, 2026).
Fees and Registration Mechanics
ACI-AGGREGATE-L1 fees are set by local sponsoring chapters, not by a single national ACI rate, so pricing varies by location and session. As one dated example, Central Texas ACI's September 12, 2026 session in Pflugerville listed $675 for full certification (both written and performance components), $475 for a written-only retest, and $525 for a performance-only retest - with the CP-44 workbook priced separately and not included in those session fees. These figures are specific to that sponsor and that date; other sponsoring groups will price sessions differently.
For a broader look at how sponsor pricing typically breaks down and what to budget for, see ACI-AGGREGATE-L1 Certification Cost 2026: Complete Pricing Breakdown. For information on how sessions are scheduled across the year, check ACI-AGGREGATE-L1 Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
| Component | Format | Key Detail |
|---|---|---|
| Written Exam | Open-book, ACI-approved references | 2-hour limit, ~100 multiple-choice questions, 60% per standard / 70% overall |
| Performance Exam | Closed-book, hands-on | Every required procedure must be completed; verbal only where permitted |
| Calculation Worksheets | Part of performance exam | 30-minute maximum per worksheet |
| Certification Window | Both components required | Must both be passed within one year of each other |
Scheduling Your Prep by Domain
Because ACI-AGGREGATE-L1 covers eight distinct paired standards, sequencing your review around those domains - rather than generic "study more" advice - is the highest-leverage thing you can do. A short timeline built around the domains looks like this:
Sampling and Reduction (Domains 1-2)
- Review AASHTO R 90/ASTM D75 sampling minimums and R 76/C702 splitting methods
- Practice quartering and mechanical splitter procedures if you have lab access
Gradation and Wash Testing (Domains 3-4)
- Drill T 11/C117 washing sequence and T 27/C136 sieve stack calculations
- Practice cumulative percent retained/passing math under time pressure
Specific Gravity and Absorption (Domains 5-6)
- Compare T 85/C127 coarse procedure against T 84/C128 fine procedure
- Focus on SSD identification differences between coarse and fine methods
Moisture, Organics, and Full Review (Domains 7-8)
- Review T 255/C566 moisture drying and T 21/C40 colorimetric test
- Run a full open-book practice exam using CP-44 as your reference
If you want a complete week-by-week framework instead of this condensed version, see ACI-AGGREGATE-L1 Study Guide 2026: How to Pass on Your First Attempt. And if you're still gauging how much effort this actually takes relative to your background, How Hard Is the ACI-AGGREGATE-L1 Exam? Complete Difficulty Guide 2026 walks through that in detail.
Who Hires Aggregate Testing Technicians
Employers who value this certification are generally the ones directly involved in aggregate and concrete quality control: materials testing laboratories, aggregate producers and quarries, ready-mix concrete suppliers, and construction firms that run their own on-site QC programs. Because the eight domains map directly to real lab and field tasks - sampling a stockpile, running a sieve analysis, checking moisture content before a batch design - the credential functions as a practical skills verification rather than a purely academic one.
If you're weighing whether pursuing this certification will actually help your job prospects or pay, ACI-AGGREGATE-L1 Salary Guide 2026: Complete Earnings Analysis and Is the ACI-AGGREGATE-L1 Certification Worth It? Complete ROI Analysis 2026 go deeper into that question. You can also browse current openings that reference the credential in ACI-AGGREGATE-L1 Jobs.
Certification Validity and Renewal
Once earned, ACI-AGGREGATE-L1 certification lasts five years. Renewal isn't a paperwork-only process - it requires retaking both the written and performance examinations again, the same as initial certification. This keeps the credential tied to demonstrated, current skill rather than a one-time achievement, which is worth planning for well before your five-year mark approaches.
For structured review tools once you're ready to test your recall against the eight domains, use the practice questions and full-length simulations available at the main ACI-AGGREGATE-L1 practice test hub. A well-organized ACI-AGGREGATE-L1 Cheat Sheet 2026: One-Page Review of Must-Know Facts can also help during final review the week before your session, and general certification details are summarized in ACI-AGGREGATE-L1 Certification.
Frequently Asked Questions
Yes. ATT1 is the abbreviation ACI uses internally in program documents like the job-task analysis, while "Aggregate Testing Technician-Level 1" and the site key "ACI-AGGREGATE-L1" refer to the identical certification.
No. There are no specific education or work-experience prerequisites for ACI-AGGREGATE-L1. Anyone can register for an approved testing session.
No. Only approved simple-function, nonprogrammable calculators are permitted. Mobile devices cannot be used as calculators under any circumstance.
You have up to one year from passing the first component to pass the second. A retest of the performance exam covers the entire component again, not just the specific procedures you missed.
Five years. Renewal requires retaking both the written and performance examinations, not just an administrative fee or continuing-education submission.