- Overview: What the 8 Domains Actually Are
- Domain 1: Sampling of Aggregates (R 90/D75)
- Domain 2: Reducing Samples to Testing Size (R 76/C702)
- Domain 3: Materials Finer than 75-µm by Washing (T 11/C117)
- Domain 4: Sieve Analysis of Fine and Coarse Aggregates (T 27/C136)
- Domain 5: Specific Gravity and Absorption, Coarse Aggregate (T 85/C127)
- Domain 6: Specific Gravity and Absorption, Fine Aggregate (T 84/C128)
- Domain 7: Total Evaporable Moisture Content (T 255/C566)
- Domain 8: Organic Impurities in Fine Aggregates (T 21/C40)
- How the Domains Map to the Written and Performance Exams
- Building a Domain-by-Domain Study Schedule
- FAQ
- ACI-AGGREGATE-L1 covers exactly eight paired AASHTO/ASTM standard areas, from sampling through organic impurities testing.
- The written exam is open-book, two hours, roughly 100 multiple-choice questions, using ACI-approved references only.
- You need at least 60% on each required standard and 70% overall to pass the written component.
- The performance exam is closed-book and requires successful completion of every required procedure, calculation worksheets capped at 30 minutes each.
Overview: What the 8 Domains Actually Are
Aggregate Testing Technician-Level 1 (ACI-AGGREGATE-L1) is organized around eight paired AASHTO/ASTM standard areas rather than abstract "domains" with percentage weightings. Each one corresponds to a specific laboratory or field procedure that a technician must know well enough to answer written questions about and, separately, physically perform under closed-book conditions. If you've read the ACI-AGGREGATE-L1 Study Guide 2026, you already know the exam has two distinct components. This article breaks down exactly what lives inside each of the eight standard areas so you know what to actually study, not just how to study it.
Because the certification workbook, CP-44 (eighth edition), includes the AASHTO standards rather than the ASTM texts, most candidates study from the AASHTO numbering (R 90, T 11, T 27, and so on) even though the ASTM equivalents (D75, C117, C136) describe the same procedures. Knowing both numbering systems matters because exam questions may reference either.
Domain 1: Sampling of Aggregates (AASHTO R 90/ASTM D75)
What This Standard Covers
Sampling is the foundation of every other domain - if a sample isn't representative, nothing downstream is valid. Candidates must understand how to obtain aggregate samples from stockpiles, conveyor belts, transportation units, and roadways in a way that avoids segregation and bias.
- Sampling locations and techniques appropriate to different source types (stockpile vs. moving belt vs. stationary source)
- Minimum sample size requirements tied to maximum aggregate particle size
- Proper handling, containers, and documentation to preserve sample integrity before it reaches the lab
Written questions on this domain often test judgment: given a described sampling scenario, which method or location introduces the least bias? Expect scenario-based multiple-choice items rather than pure definition recall.
Domain 2: Reducing Samples to Testing Size (AASHTO R 76/ASTM C702)
What This Standard Covers
Once a field sample is obtained, it's almost always larger than what's needed for a given test. This domain covers the accepted methods for splitting that sample down without distorting its gradation or composition.
- Mechanical splitter (riffle splitter) technique and proper loading
- Quartering method for reducing samples without mechanical equipment
- Miniature stockpile sampling method as an alternative reduction technique
On the performance exam, this is a hands-on procedure that examiners watch closely - sloppy splitter technique or uneven quartering is an easy way to fail a required procedure. This is one of the areas candidates most often underestimate before they've actually watched or practiced it in person.
Domain 3: Materials Finer than 75-µm (No. 200) Sieve by Washing (AASHTO T 11/ASTM C117)
What This Standard Covers
This test determines the amount of material passing the No. 200 sieve after a wash procedure, which is critical for identifying excess fines that can affect concrete workability and durability.
- Correct washing technique to avoid loss of coarser particles
- Drying requirements before and after the wash
- Calculating percent finer than 75-µm from mass before and after washing
Because this procedure is frequently combined with sieve analysis (Domain 4) in practice, expect written questions that connect the two - for example, how a washed loss figure gets incorporated into a full gradation report.
Domain 4: Sieve Analysis of Fine and Coarse Aggregates (AASHTO T 27/ASTM C136)
What This Standard Covers
Sieve analysis is arguably the most calculation-heavy of the eight domains. Candidates must be able to run a full gradation test and correctly compute the results by hand using an approved calculator.
- Proper sieve stacking order and shaking duration/technique
- Calculating percent retained, percent passing, and cumulative percentages per sieve
- Checking mass balance to confirm no material was lost during the test
Domain 5: Specific Gravity and Absorption of Coarse Aggregate (AASHTO T 85/ASTM C127)
What This Standard Covers
This domain tests understanding of bulk specific gravity, bulk saturated-surface-dry (SSD) specific gravity, apparent specific gravity, and absorption for coarse aggregate.
- Achieving and recognizing the SSD condition for coarse particles
- Submerged mass determination using a wire basket and water bath
- Formula-based calculation of each specific gravity value and absorption percentage
This is one of two "specific gravity" domains, and candidates frequently mix up which formulas and equipment apply to coarse versus fine aggregate. Keep a clean reference sheet distinguishing Domain 5 from Domain 6 as you study.
Domain 6: Specific Gravity and Absorption of Fine Aggregate (AASHTO T 84/ASTM C128)
What This Standard Covers
The fine aggregate counterpart to Domain 5, this procedure uses a pycnometer and requires a different SSD verification method - the cone slump test - since fine particles can't be visually inspected for surface moisture the way coarse particles can.
- Cone test technique to confirm SSD condition in fine aggregate
- Pycnometer calibration and volume displacement calculation
- Bulk, bulk SSD, apparent specific gravity, and absorption formulas specific to fine aggregate
Performance graders watch closely for correct cone-slump technique - too much or too little tamping produces a false SSD reading, which cascades into an incorrect specific gravity result.
Domain 7: Total Evaporable Moisture Content by Drying (AASHTO T 255/ASTM C566)
What This Standard Covers
This domain covers determining the total moisture content of an aggregate sample by comparing wet and dry mass after drying to a constant mass.
- Proper drying method and equipment (oven, hot plate, or other approved heat source)
- Recognizing "constant mass" versus premature termination of drying
- Moisture content calculation as a percentage of dry mass
This procedure often ties into batching corrections used in concrete production, so written questions may frame it in a practical field context rather than as an isolated lab calculation.
Domain 8: Organic Impurities in Fine Aggregates for Concrete (AASHTO T 21/ASTM C40)
What This Standard Covers
This qualitative test uses a sodium hydroxide solution and a color-comparison standard to detect organic impurities in fine aggregate that could interfere with concrete setting and strength.
- Correct reagent preparation and sample-to-solution ratio
- Standing time before color comparison
- Comparing resulting solution color against organic plate or standard color solution references
Unlike the calculation-based domains, this test is judged by visual comparison, so written questions here tend to focus on procedure sequencing and safe reagent handling rather than arithmetic.
How the Domains Map to the Written and Performance Exams
All eight domains show up across both exam components, but they're tested differently. The written examination is open-book using ACI-approved references, runs on a two-hour limit, and contains approximately 100 multiple-choice questions drawn from across all eight standards. To pass, you need at least 60% on each required standard and 70% overall - meaning you can't coast through by acing a few domains while bombing others.
The performance examination is closed-book and requires successful completion of every required procedure across the eight domains, with verbal descriptions permitted only where the standard allows it. Calculation worksheets tied to specific procedures are capped at 30 minutes each - this is a per-worksheet limit, not a single 30-minute cap for the entire performance exam. Both the written and performance components must be passed within one year of each other, and if you fail one, your retest covers that entire component again, not just the domains you missed.
| Exam Component | Format | Passing Standard |
|---|---|---|
| Written Exam | Open-book, ACI-approved references, ~100 multiple-choice questions, 2-hour limit | 60% minimum per required standard, 70% overall |
| Performance Exam | Closed-book, hands-on procedures across all 8 domains, worksheets capped at 30 min each | Successful completion of every required procedure |
Key Takeaway
Don't study the eight domains as isolated flashcard topics. Study them as procedures you'll physically demonstrate, because the performance exam grades execution, not memorization. For a deeper breakdown of exactly what score you need on each component, see the ACI-AGGREGATE-L1 Passing Score 2026 guide.
Building a Domain-by-Domain Study Schedule
Because there are eight domains and two very different exam formats to prepare for, most candidates benefit from sequencing their study so foundational domains come first and calculation-heavy domains get extra repetition. A simple four-week structure works well for many candidates preparing alongside a full-time job.
Sampling and Reduction Fundamentals
- Master Domain 1 (sampling) and Domain 2 (sample reduction) since every later test depends on getting a valid sample first
- Practice splitter and quartering technique physically, not just by reading the standard
Gradation and Washing
- Work through Domain 3 (washing) and Domain 4 (sieve analysis) together since they're often run in sequence
- Drill the percent-passing and percent-retained calculations until they're automatic
Specific Gravity Pair
- Study Domain 5 (coarse) and Domain 6 (fine) side by side to lock in the differences in SSD verification and equipment
- Build a formula reference card distinguishing bulk, bulk SSD, and apparent specific gravity for each
Moisture, Organics, and Full Review
- Finish Domain 7 (moisture content) and Domain 8 (organic impurities)
- Run a full practice cycle across all eight domains and rehearse the performance procedures start to finish
If you want a condensed, print-friendly version of the formulas and thresholds across all eight domains, the ACI-AGGREGATE-L1 Cheat Sheet 2026 is designed to sit alongside this domain breakdown. And if you're still deciding whether the certification fits your career plans, the ROI analysis and jobs guide cover who typically hires ACI-AGGREGATE-L1 holders, including aggregate producers, ready-mix concrete testing labs, and highway materials programs.
Once you've mapped out which domains need the most repetition, running timed practice questions against realistic multiple-choice formats on our practice test platform is one of the fastest ways to find weak spots before exam day. It's also worth reviewing how the exam is typically scheduled through sponsoring groups - the exam dates guide walks through testing windows and deadlines in more detail, and the cost breakdown explains what a full certification cycle, including workbook and potential retests, typically involves.
FAQ
The certification does not publish domain-by-domain weightings the way some percentage-based exams do. Instead, passing requires at least 60% on each required standard and 70% overall, so every domain has to be handled competently rather than relying on strength in a few areas.
It helps to recognize both, since the workbook (CP-44, eighth edition) uses AASHTO numbering while the domains are officially paired with ASTM equivalents. Questions may reference either system, so familiarity with both reduces confusion on exam day.
Candidates most often struggle with the two specific gravity domains (5 and 6) because of the SSD determination techniques and multiple similar-looking formulas, and with sample reduction technique (Domain 2) on the performance exam, since it's a physical skill that's easy to underpractice.
Yes. Both components must be passed within one year of each other, and a retest only covers the entire component you failed, not the one you already passed.
See What Is ACI-AGGREGATE-L1? and ACI-AGGREGATE-L1 Certification for an overview, or How Hard Is the ACI-AGGREGATE-L1 Exam? for a difficulty-focused breakdown that complements this domain guide.