What Is ACI-AGGREGATE-BASE Certification?

ACI-AGGREGATE-BASE is the shorthand this site uses for the Aggregate Base Testing Technician-ASTM Methods credential. It is administered under American Concrete Institute (ACI) certification programs, with testing delivered through approved sponsoring groups and ACI-trained examiners and proctors, and grading performed by ACI. This is not a generic "aggregate testing" badge - it is a specific credential tied to a defined set of ASTM test methods used to evaluate base and subbase materials in roadway, pavement, and site development work.

It's worth being precise about lineage here: this ASTM Methods track is one of the successors to an earlier, now-retired combined-methods Aggregate Base program. A parallel AASHTO Methods track also exists as a separate credential with its own workbook and job-task analysis. If you're researching what the letters actually mean before committing study time, our companion piece on what ACI-AGGREGATE-BASE is and the breakdown of what the designation actually stands for both dig into that naming history in more detail.

Why the Distinction Matters: Because the retired combined program and the current AASHTO and ASTM tracks all trace back to the same subject area, candidates sometimes study the wrong workbook or reference the wrong job-task analysis. Confirm you're preparing for the ASTM Methods version - CP-46, not CP-47 - before you buy materials.

Who Administers It and Where It Fits

The American Concrete Institute governs this certification through its published policy, currently CPP 620.5-25, approved February 14, 2025. The job-task analysis underlying the current ASTM Methods exam content was approved February 13, 2026, which means the exam reflects a relatively recent review of what field and lab technicians actually need to know when testing aggregate base materials against ASTM standards.

Testing itself does not happen at a generic testing center chain - it's delivered by ACI-approved sponsoring organizations, using ACI-trained examiners and proctors to run both the written and performance portions. ACI performs the grading. If you want the full regulatory and policy picture, including how this differs from the retired program, see our detailed requirements and eligibility breakdown.

Exam Structure: Written and Performance Components

Certification requires passing two distinct components, and understanding their format differences matters as much as knowing the content.

Written Examination

The written exam is open-book, but only ACI-approved references may be used during the session. Candidates get a two-hour time limit to answer approximately 75 multiple-choice questions drawn from the seven ASTM standard sections.

Open-book format still demands familiarity - you won't have time to look up every answer
Approved simple-function, nonprogrammable calculators are allowed
Mobile devices cannot be used as calculators under any circumstance

Performance Examination

The performance exam is closed-book and requires successful, hands-on demonstration of every required procedure. Verbal description of a step is only accepted where the official checklist specifically permits it - you generally cannot talk your way through a procedure that requires physical demonstration.

For a full comparison of question style, timing pressure, and how the two components interact, read our dedicated look at how hard the ACI-AGGREGATE-BASE exam actually is.

The Seven ASTM Domains You Must Master

Unlike some certifications that split content into evenly weighted categories, this credential's seven "domains" are simply the official ASTM standard sections themselves - they are not allocated equal weight on the exam. That distinction changes how you should prioritize study time.

Domain 1 - ASTM D75/D75M: Sampling of Aggregates

Standard practice for obtaining representative field samples before any testing occurs. Improper sampling technique invalidates downstream results, so this is foundational.

Domain 2 - ASTM C702/C702M: Reducing Samples to Testing Size

Covers mechanical and manual splitting methods used to reduce a field sample to a size appropriate for laboratory testing without introducing bias.

Domain 3 - ASTM D4318: Liquid Limit, Plastic Limit, and Plasticity Index

Atterberg limits testing on the fine fraction of base material, used to classify soil behavior and suitability.

Domain 4 - ASTM D7928: Particle-Size Distribution via Hydrometer Analysis

Sedimentation-based gradation testing for fine-grained soils, filling in the gradation picture below what sieve analysis can measure.

Domain 5 - ASTM D2216: Laboratory Water (Moisture) Content by Mass

A core moisture-determination procedure referenced repeatedly across other test methods and compaction calculations.

Domain 6 - ASTM D1557: Compaction Characteristics Using Modified Effort

Laboratory compaction testing at 56,000 ft-lbf/ft³ (2,700 kN-m/m³), used to establish maximum dry density and optimum moisture under modified effort.

Domain 7 - ASTM D698: Compaction Characteristics Using Standard Effort

The standard-effort counterpart at 12,400 ft-lbf/ft³ (600 kN-m/m³), commonly compared against Domain 6 results on the exam.

For a section-by-section breakdown of exactly what each standard tests and how questions tend to be framed, see our full exam domains guide.

Key Takeaway

Because the seven domains map directly to ASTM standard numbers rather than equal-weight buckets, memorize which standard governs which procedure first - confusing D1557 with D698 details, or D75 sampling steps with C702 reduction steps, is a common source of missed points.

Scoring, Retesting, and the One-Year Rule

The passing threshold on the written exam has two layers: candidates must score at least 60% within every required standard section and at least 70% overall. Scoring well overall but weak in one domain-section will not clear the bar. The performance exam has its own pass condition - successful demonstration of all required procedures per the checklist.

Both the written and performance components must be passed within a one-year window of each other. If a retest is needed, it covers the entire failed component, not just the specific sections or procedures missed - there is no partial retest option for individual weak spots. That makes preparation across all seven domains important rather than optional. Our passing score deep-dive walks through the section-by-section math in more detail.

Component	Format	Passing Standard
Written Exam	Open-book (ACI-approved references), 2-hour limit, ~75 multiple-choice questions	60% minimum per required section, 70% overall
Performance Exam	Closed-book, hands-on demonstration, verbal only where checklist permits	Successful demonstration of all required procedures

Pathways: AASHTO Holders and Level 1 Exemptions

There are two documented shortcuts into this specific ASTM credential, and both are worth checking before you assume you need to start from zero.

Current AASHTO Methods holders: If you already hold the separate Aggregate Base Testing Technician-AASHTO certification, you can earn this ASTM credential by passing only the ASTM written examination, provided you do so within one year of obtaining the AASHTO certification.
Current Aggregate Testing Technician-Level 1 holders: Candidates who already hold this credential may receive specified exemptions on certain performance-procedure requirements.

Neither pathway eliminates the need to understand the seven ASTM standard sections for written-exam purposes. See full eligibility requirements for the specifics of qualifying prerequisites.

Materials, Calculators, and Workbook Costs

The official workbook for this track is CP-46, first edition, and candidates should use it along with any applicable errata ACI has published for that edition. Do not confuse it with CP-47, which belongs strictly to the separate AASHTO Methods track - using the wrong workbook is a real risk given how similarly the two credentials are named.

As of a September 10, 2026 check, ACI listed CP-46 at $133 for non-members and $69 for ACI members. These figures are workbook prices only, not examination or certification fees, so budget for the workbook and the separate registration/testing costs independently. For a fuller cost picture across workbook, registration, and renewal, see our certification cost breakdown.

On exam day, approved simple-function, nonprogrammable calculators are permitted for the written exam. Mobile phones, even in calculator mode, are not acceptable substitutes - bring a dedicated calculator.

Renewal Reminder: Certification is valid for five years. Renewal requires passing both the written and performance examinations again - there is no simple continuing-education renewal path for this credential.

Who Actually Needs This Credential

This certification is built for technicians performing or supervising aggregate base sampling and testing under ASTM methods - typically in geotechnical labs, materials testing firms, DOT-adjacent construction quality programs, and site-development or pavement-subgrade projects where base material properties must be documented against ASTM standards rather than AASHTO's parallel framework. If your employer or project specifications explicitly call out ASTM test methods (D75, C702, D4318, D7928, D2216, D1557, D698), this is the matching credential - not the AASHTO track and not the retired combined program.

If you're weighing whether pursuing it is worth the time investment against career or project requirements, our ROI analysis and earnings-related guide go into that decision in more depth. For a sense of where certified technicians typically find work, see job opportunities tied to this certification.

A Domain-Aware Approach to Preparation

Rather than generic study advice, the smartest sequencing here follows the exam's own structure: since each of the seven domains is a full ASTM standard with its own required 60% minimum, uneven prep creates real risk even if your overall knowledge feels strong.

Early

Sampling and Reduction Fundamentals

Work through D75/D75M sampling procedures
Practice C702/C702M splitting and reduction steps

Middle

Soil Classification Testing

Drill into D4318 Atterberg limits calculations
Study D7928 hydrometer analysis and D2216 moisture content procedures

Late

Compaction Comparisons

Contrast D1557 modified effort with D698 standard effort
Run full practice sets covering all seven domains together

Because the written exam is open-book, part of your preparation should include practicing efficient navigation of your approved references under time pressure - two hours for roughly 75 questions leaves little room for slow searching. Our study guide and condensed one-page cheat sheet are built around that same domain sequencing, and running timed questions on our practice test platform before exam day helps convert reference familiarity into actual speed.

Before you lock in a testing date, also confirm current exam scheduling windows and deadlines, since both components must be completed within the one-year pairing rule described earlier.

Frequently Asked Questions

Is ACI-AGGREGATE-BASE the same as the AASHTO Methods credential?

No. They are separate credentials under the same general Aggregate Base Testing Technician program area. This article covers the ASTM Methods track specifically, which uses the CP-46 workbook rather than the AASHTO track's CP-47.

How many questions are on the written exam and how long do I get?

The written exam contains approximately 75 multiple-choice questions and must be completed within a two-hour limit. It is open-book, but only ACI-approved references may be used.

What score do I need to pass?

You need at least 60% within every required standard section and at least 70% overall on the written exam. The performance exam requires successful demonstration of all required procedures per the checklist.

What happens if I fail one component?

A retest covers the entire failed component - either the full written exam or the full performance exam - rather than just the specific sections or procedures you missed. Both components must ultimately be passed within one year of each other.

Can I use my phone as a calculator during the written exam?

No. Only approved simple-function, nonprogrammable calculators are permitted. Mobile devices cannot be used as calculators under exam rules.

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