- Overview: What "7 Domains" Actually Means for This Exam
- Domain 1: ASTM D75/D75M - Sampling Aggregates
- Domain 2: ASTM C702/C702M - Reducing Samples to Testing Size
- Domain 3: ASTM D4318 - Liquid Limit, Plastic Limit, Plasticity Index
- Domain 4: ASTM D7928 - Hydrometer (Sedimentation) Analysis
- Domain 5: ASTM D2216 - Moisture Content of Soil and Rock
- Domain 6: ASTM D1557 - Modified Effort Compaction
- Domain 7: ASTM D698 - Standard Effort Compaction
- Written vs. Performance Exam: How Domains Show Up in Each
- Are the Domains Weighted Equally?
- Mapping Domains to a Study Schedule
- FAQ
- The 7 domains are the actual ASTM standard sections in CP-46, not an arbitrary equal-weight breakdown.
- You must score at least 60% on every required standard section and 70% overall to pass the written exam.
- The written exam is open-book, two hours, roughly 75 multiple-choice questions using ACI-approved references only.
- The closed-book performance exam requires hands-on demonstration of procedures tied to these same 7 domains.
Overview: What "7 Domains" Actually Means for This Exam
Unlike certifications that slice content into abstract "knowledge areas," the Aggregate Base Testing Technician-ASTM Methods credential organizes its content around seven specific ASTM standards. Each one corresponds to a real laboratory or field procedure a technician performs on soil and aggregate base materials. Understanding this structure matters because ACI's job-task analysis for the ASTM track - approved February 13, 2026 - draws exam questions directly from these standards, and the ACI-approved workbook (CP-46, first edition) is organized the same way.
If you're just getting oriented to this credential, it helps to first read What Is ACI-AGGREGATE-BASE? and ACI-AGGREGATE-BASE Certification before diving into domain-level detail. This guide assumes you already know the exam exists and want to know exactly what's tested inside each of the seven sections.
Domain 1: ASTM D75/D75M - Standard Practice for Sampling Aggregates
What this domain covers
D75/D75M governs how aggregate samples are obtained so that they represent the material being tested - from stockpiles, conveyor belts, transportation units, and roadways. Technicians must understand why improper sampling location and technique invalidates every downstream test result, no matter how carefully those later tests are run.
- Sampling from moving streams, stockpiles, and transportation units
- Minimum sample size requirements based on aggregate size
- Proper equipment for obtaining representative samples
- Handling and protecting samples between the field and the lab
Expect exam questions that test your understanding of why a sampling method is specified for a given condition, not just rote memorization of a procedure list. Because this is the first standard in the sequence, errors here propagate into every other domain's test.
Domain 2: ASTM C702/C702M - Standard Practice for Reducing Samples of Aggregate to Testing Size
What this domain covers
Once a field sample is obtained, it's almost always too large to test directly. C702/C702M describes the mechanical splitter and quartering methods used to reduce bulk samples down to a testing-size portion without introducing bias.
- Mechanical splitter procedure and calibration checks
- Quartering method on a clean, hard surface
- Miniature stockpile sampling technique
- Choosing the correct reduction method for sample moisture and gradation
This domain pairs tightly with Domain 1 - questions often present a sampling scenario and then ask which reduction method is appropriate for the material condition described.
Domain 3: ASTM D4318 - Liquid Limit, Plastic Limit, and Plasticity Index of Soils
What this domain covers
D4318 addresses Atterberg limits testing, a core classification tool for fine-grained soils used in aggregate base evaluation. Candidates need working familiarity with both the multipoint and one-point liquid limit methods, plus the plastic limit rolling procedure.
- Liquid limit device setup, groove cutting, and drop-count technique
- One-point versus multipoint liquid limit calculation methods
- Plastic limit determination by hand-rolling threads
- Computing the plasticity index from liquid and plastic limit results
This is one of the more calculation-heavy domains, so make sure your approved simple-function calculator skills are sharp - mobile devices cannot be used as calculators during the written exam.
Domain 4: ASTM D7928 - Particle-Size Distribution (Gradation) of Fine-Grained Soils Using Sedimentation (Hydrometer) Analysis
What this domain covers
D7928 extends particle-size analysis below the range sieves can measure, using hydrometer readings and sedimentation principles (Stokes' Law behavior) to characterize the fine fraction of a soil sample.
- Sample preparation, dispersion, and pretreatment steps
- Hydrometer reading technique and correction factors
- Temperature and meniscus corrections
- Interpreting sedimentation data into a particle-size distribution curve
Because this procedure involves multiple correction steps, expect questions that test whether you know when a correction applies, not just the raw formula. This tends to be one of the harder domains for candidates without prior soils-lab experience - a theme explored further in How Hard Is the ACI-AGGREGATE-BASE Exam? Complete Difficulty Guide 2026.
Domain 5: ASTM D2216 - Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
What this domain covers
D2216 is the standard oven-drying moisture content test, and it's foundational because moisture content values feed directly into the compaction calculations in Domains 6 and 7.
- Specimen mass minimums based on maximum particle size
- Oven temperature and drying-to-constant-mass criteria
- Correct sequence of tare, wet mass, and dry mass measurements
- Calculating percent moisture content and identifying common rounding errors
This is a comparatively straightforward domain conceptually, but exam questions often embed it inside a compaction-test scenario, so you need to recognize D2216 steps even when they're not labeled as such.
Domain 6: ASTM D1557 - Laboratory Compaction Characteristics of Soil Using Modified Effort
What this domain covers
D1557 covers the modified Proctor compaction test (56,000 ft-lbf/ft³), used to establish maximum dry density and optimum moisture content under higher compactive effort - relevant for base materials under heavier loading conditions.
- Method selection (A, B, or C) based on gradation and mold size
- Rammer drop height, weight, and layer/blow-count requirements
- Oversize particle correction procedures
- Plotting the moisture-density curve and reading maximum dry density
Domain 7: ASTM D698 - Laboratory Compaction Characteristics of Soil Using Standard Effort
What this domain covers
D698 mirrors D1557's structure but uses standard compactive effort (12,400 ft-lbf/ft³). The exam frequently tests whether candidates can distinguish which standard applies to a given project specification and correctly identify the differences in mold size, rammer weight, and blow counts between the two.
- Standard effort method selection and equipment specifications
- Recognizing the numerical differences between standard and modified effort setups
- Layer count and compaction sequence for each method variant
- Comparing standard vs. modified maximum dry density outcomes conceptually
| Domain | ASTM Standard | Core Skill Tested |
|---|---|---|
| 1 | D75/D75M | Representative field sampling technique |
| 2 | C702/C702M | Reducing samples to testing size without bias |
| 3 | D4318 | Liquid limit, plastic limit, plasticity index |
| 4 | D7928 | Hydrometer sedimentation analysis of fines |
| 5 | D2216 | Oven-drying moisture content determination |
| 6 | D1557 | Modified effort compaction curve |
| 7 | D698 | Standard effort compaction curve |
Written vs. Performance Exam: How Domains Show Up in Each
The written examination is open-book, meaning you may use ACI-approved references during the two-hour, approximately 75-question multiple-choice session. But "open-book" doesn't mean "easy" - with roughly 75 questions spread across seven distinct standards in two hours, you have limited time to look up every answer. Passing requires at least 60% in every required standard section and 70% overall, so you can't coast through a weak domain by over-performing on an easier one.
The performance examination is closed-book and requires you to physically demonstrate the required procedures from these same domains, with verbal description permitted only where the checklists explicitly allow it. This means memorizing the general idea of a test isn't enough - you need muscle memory for the actual steps, especially for hands-heavy domains like D4318's plastic limit rolling or the compaction procedures in D1557 and D698.
Key Takeaway
Both components must be passed within one year of each other, and a retest covers the entire failed component - not just the sections you missed. Treat every domain as pass/fail territory, not a point-banking exercise.
For a deeper breakdown of exactly how the 60%/70% thresholds work in practice, see ACI-AGGREGATE-BASE Passing Score 2026: Exactly What You Need to Pass.
Are the Domains Weighted Equally?
No - the seven domain entries are the official ASTM standard sections in the job-task analysis, not an equal-weight allocation across the exam. Some standards involve more procedural steps and calculation types (like D4318 and D7928) and naturally generate more question opportunities than a narrower standard. Rather than guessing at weighting, plan to reach the required minimum in every section, since the 60%-per-section rule means no domain can be safely ignored regardless of its apparent size.
If you're deciding whether the overall investment in preparing for all seven domains is worthwhile relative to your career goals, Is the ACI-AGGREGATE-BASE Certification Worth It? Complete ROI Analysis 2026 walks through that decision in more depth.
Mapping Domains to a Study Schedule
A simple way to structure preparation is to group domains by workflow stage rather than study them in numerical order alone - sampling and sample reduction first, since every later test depends on a properly prepared specimen, then move into classification testing, then finish with the two compaction standards, which build on the moisture-content skills from Domain 5.
Sampling & Sample Prep
- Study D75/D75M sampling locations and equipment
- Study C702/C702M reduction methods and when each applies
Soil Classification
- Drill D4318 liquid limit and plastic limit calculations
- Work through D7928 hydrometer correction factors
Moisture & Compaction
- Master D2216 oven-drying procedure and moisture math
- Compare D1557 vs. D698 rammer weights, drops, and effort values side by side
Integration & Performance Practice
- Run full practice questions across all seven domains
- Rehearse performance-exam procedures under closed-book conditions
For a more detailed, day-by-day approach to first-attempt preparation, see the ACI-AGGREGATE-BASE Study Guide 2026: How to Pass on Your First Attempt. And once you've internalized the seven domains, a condensed reference like the ACI-AGGREGATE-BASE Cheat Sheet 2026: One-Page Review of Must-Know Facts can help during final review.
You can also build domain-specific familiarity by working through timed practice questions on our practice test platform, which mirrors the open-book, multiple-choice format of the actual written exam.
FAQ
The written exam covers knowledge across all seven ASTM standard sections in multiple-choice format. The performance exam requires physical demonstration of the required procedures tied to these standards, with verbal description allowed only where checklists permit it.
Many candidates find ASTM D7928 (hydrometer analysis) and the D1557/D698 compaction pair challenging because of multiple correction factors and easily confused procedural details. See How Hard Is the ACI-AGGREGATE-BASE Exam? Complete Difficulty Guide 2026 for more detail.
No. Approved simple-function, nonprogrammable calculators are permitted, but mobile devices cannot be used as calculators during the exam.
CP-46, first edition, is the ASTM workbook covering all seven domains, and candidates should apply its applicable errata. It's listed by ACI at $133 non-member/$69 member (checked September 10, 2026), which reflects workbook pricing, not the examination fee itself.
A current AASHTO Methods holder can earn the ASTM credential by passing the ASTM written examination within one year of obtaining AASHTO certification, so you'd still need to prepare for these seven ASTM-specific domains. Eligibility nuances are covered in ACI-AGGREGATE-BASE Requirements 2026: Eligibility, Prerequisites & How to Qualify.