Study guide
1.1 ACI Certification Overview, Exam Structure & Passing Rules
ACI Aggregate Testing Technician Level 1 Exam
Track your progress as you read
Finished sections get a check mark.
1 Chapter 1: Certification Overview & Aggregate Fundamentals
1.1 ACI Certification Overview, Exam Structure & Passing Rules 1.2 Aggregate Classifications, Sieve Designations & ASTM C33 Specifications 1.3 Aggregate Moisture States, Phase Relationships & Mix Water Adjustments
2 Chapter 2: Sampling and Sample Reduction (ASTM D75 & ASTM C702)
2.1 ASTM D75 / AASHTO R 90: Scope, Segregation Mechanics & Minimum Field Sample Mass 2.2 ASTM D75 Sampling Procedures by Source: Belts, Streams, Stockpiles, Transportation Units & Roadways 2.3 ASTM C702 / AASHTO R 76: Reducing Field Samples to Testing Size
3 Chapter 3: Washing Test & Organic Impurities (ASTM C117 & ASTM C40)
3.1 ASTM C117 / AASHTO T 11: Apparatus, Specimen Masses & Washing Procedures A and B 3.2 ASTM C117: Calculation, Reporting Rules & ASTM C33 Fines Limits 3.3 ASTM C40 / AASHTO T 21: Organic Impurities in Fine Aggregates
4 Chapter 4: Sieve Analysis and Gradation (ASTM C136 & Fineness Modulus)
4.1 ASTM C136 / AASHTO T 27: Apparatus, Specimen Masses, Stack Assembly & Sieving Sufficiency 4.2 ASTM C136: Sieve Overload Limits, the 0.3% Mass Check, Oversize Particles & Split-Portion Arithmetic 4.3 Gradation Calculations, Reporting & Combined Wash-Sieve Analysis 4.4 Fineness Modulus (FM) Calculation, Application & Uniformity Limits
5 Chapter 5: Specific Gravity and Absorption of Coarse Aggregate (ASTM C127)
5.1 ASTM C127 / AASHTO T 85: Test Procedure & Wire Basket Buoyancy 5.2 Relative Density (Specific Gravity) and Absorption Calculations for Coarse Aggregate 5.3 Multi-Fraction Testing, Weighted Averages, Reporting & Precision for Coarse Aggregate
6 Chapter 6: Specific Gravity and Absorption of Fine Aggregate (ASTM C128)
6.1 ASTM C128 / AASHTO T 84: Pycnometer Method & Test Preparation 6.2 The Cone and Tamper Test for Saturated Surface-Dry (SSD) Condition 6.3 Relative Density and Absorption Calculations for Fine Aggregate
7 Chapter 7: Moisture Content & Performance Examination Preparation (ASTM C566 & Practical Lab Skills)
7.1 ASTM C566 / AASHTO T 255: Total Evaporable Moisture Content by Drying 7.2 Surface Moisture Determination and Concrete Batch Plant Adjustments 7.3 ACI Performance Examination Mastery & Practical Lab Checklists
1.1 ACI Certification Overview, Exam Structure & Passing Rules
Key Takeaways Explain This Topic AI
ACI Aggregate Testing Technician Level 1 certification requires passing both a 2-hour open-book written examination (~100 questions) and a closed-book performance examination demonstrating all eight standards.
The passing standard requires achieving a minimum of 70% on the overall written examination AND at least 60% on the individual question subsection for EACH of the eight required ASTM/AASHTO standards; failing a single standard fails the entire written exam.
The closed-book performance examination judges the examinee on the ability to correctly perform or describe all of the required procedures for each of the eight standards, with no reference materials permitted.
Certification is valid for exactly 5 years, with no renewal through continuing education units (CEUs); recertification requires re-taking and passing both the complete written and performance examinations.
The curriculum is anchored to the ACI CP-44 Technician Workbook (8th Edition), which contains the program information, checklists, and resource materials for the eight core standards: ASTM D75, C702, C117, C136, C127, C128, C566, and C40.
Last updated: September 2026
Official Credential & Professional Purpose
The ACI Aggregate Testing Technician Level 1 certification is an internationally recognized professional credential administered by the American Concrete Institute (ACI). This credential officially certifies that an individual has demonstrated the fundamental knowledge and practical hands-on skills necessary to properly sample, process, test, and evaluate mineral aggregates used in hydraulic-cement concrete, asphaltic paving mixtures, and structural base courses.
In modern civil engineering construction, mineral aggregates comprise approximately 60% to 75% of the total volume of concrete and up to 90% to 95% of asphalt mixtures . Consequently, the structural integrity, durability, workability, and economics of any construction project depend directly on the physical and chemical characteristics of these aggregates. If sampling is biased, sample reduction is non-representative, or test procedures deviate from standardized methods, the test results become legally and technically invalid—potentially leading to catastrophic structural failures, costly mix redesigns, or project rejections.
Career Context & Industry Recognition
Possession of the ACI Aggregate Testing Technician Level 1 card is an industry-standard requirement across multiple civil engineering and materials testing sectors:
Ready-Mix Concrete & Asphalt Production: Batch plant quality control (QC) technicians rely on daily aggregate testing to verify gradations, compute moisture corrections, and adjust mixing water.
Commercial Testing Laboratories: Independent quality assurance (QA) laboratories must maintain accredited personnel under ASTM E329 and ASTM C1077, both of which require certified technicians for aggregate testing.
State Departments of Transportation (DOTs) & Municipal Agencies: Highway agencies mandate certified personnel for material acceptance sampling and testing on public infrastructure projects.
Geotechnical & Earthwork Operations: Base-course contractors and aggregate quarry producers use these standardized procedures to certify quarry ledges, gravel pits, and manufactured sand operations.
Prerequisite Ladder: ACI requires a current Aggregate Testing Technician—Level 1 certification before it will grant Aggregate Testing Technician—Level 2 , which covers the advanced laboratory procedures. There are no prerequisites for Level 1 itself — no education, experience, or prior certification requirement.
The Two-Part Examination Structure
Obtaining ACI Aggregate Testing Technician Level 1 certification requires satisfying two completely independent, rigorous evaluation components: the Written Examination and the Performance Examination . +--------------------------------------------------------------------------+
- | ACI CERTIFICATION REQUIREMENTS |
- +--------------------------------------------------------------------------+
- |
- +----------------------------+----------------------------+
- | |
- v v
- +--------------------------------+ +--------------------------------+
- | WRITTEN EXAMINATION | | PERFORMANCE EXAMINATION |
- | - Open-Book (CP-44 / Standards)| | - Closed-Book (From Memory) |
- | - 2-Hour Time Limit | | - 8 Individual Standard Tables |
- | - ~100 Multiple-Choice Items | | - Hands-on Physical Execution |
- | - 8-12 Questions per Standard | | - Step-by-Step Checklist |
- +--------------------------------+ +--------------------------------+
- | |
- v v
- +--------------------------------+ +--------------------------------+
- | PASSING CRITERIA | | PASSING CRITERIA |
- | 1. Overall Score >= 70% | | Correctly perform OR describe |
- | 2. EACH Standard >= 60% | | ALL required procedures for |
- | | | EACH of the 8 standards |
- +--------------------------------+ +--------------------------------+
- | |
- +----------------------------+----------------------------+
- |
- v
- +--------------------------------+
- | 5-YEAR CERTIFICATION |
- | (No CEU Renewal Allowed) |
- +--------------------------------+
- 1. Written Examination Mechanics
Format: Open-book written exam administered in a proctored setting (paper-and-pencil or computer-based testing).
Duration: Exactly 2 hours (120 minutes).
Length: Approximately 100 multiple-choice questions, with 8 to 12 questions on each standard — ACI publishes the same allowance for all eight, so no standard is safe to skip.
Authorized Reference Material: The written examination is open-book. Examinees work from the official ACI CP-44 Technician Workbook (8th Edition) and copies of the governing ASTM/AASHTO standards. Confirm the exact reference-material and calculator rules with your sponsoring group before exam day, since administration details are set locally.
2. Performance (Practical) Examination Mechanics
Format: Closed-book practical examination.
Execution: Examinees must demonstrate, hands-on and from memory, the physical procedures for each of the eight standards before an authorized ACI certification examiner.
Checklist Evaluation: The examiner scores the candidate against a standardized rubric of critical procedural steps published in ACI CP-44. In ACI's own words, the examinee is judged on the ability to correctly perform or describe all of the required procedures for each standard , without prompting or coaching.
Verbalization Requirements: Certain actions (such as splitting sequences, visual decantation observations, or safety protocols) must be verbally articulated while being demonstrated.
The "Double Hurdle" Passing Criteria & Recertification Rules
The grading system for the ACI Aggregate Level 1 Written Examination utilizes a rigorous "Double Hurdle" threshold. Many candidates fail the written examination not because of their overall score, but because they neglected one individual standard.
The Dual Written Passing Rule
To earn a passing grade on the written examination, a candidate must achieve BOTH of the following:
An overall composite score of at least 70% across the entire ~100-question examination.
A sub-score of at least 60% on the questions associated with EACH of the eight individual standards .
Warning
The 60% Standard Trap: Even if a candidate earns a 92% overall composite score on the written exam, if that candidate scores 50% (e.g., 5 out of 10) on the ASTM C128 (Fine Aggregate Specific Gravity) section, the candidate FAILS the written examination . There is no rounding up or grade averaging across standards.
Performance Exam Scoring & Retest Policies
ACI states the performance requirement in one sentence: the examinee is judged on his or her ability to correctly perform or describe all of the required procedures for each standard. Certification is granted only to applicants who achieve both a passing grade on the written examination and successful completion of the performance examination.
Warning
ACI does not publish a universal retest rule for this program, so do not memorize one. Retest eligibility, waiting periods, whether individual failed standards may be re-attempted separately, the length of time a passed written result stays valid while you re-sit the performance exam, and the fee for each attempt are all set by the local ACI chapter or sponsoring group that administers your session . Get those terms in writing from your sponsoring group before you register. Any specific figure you see quoted online — a 12-month window, a two-standard threshold, a fixed number of attempts — is a chapter practice or an invention, not an ACI-published national policy.
Recertification Policy
Validity Period: ACI Aggregate Testing Technician Level 1 certification is valid for exactly 5 years from the date all examination requirements are satisfied.
No Continuing Education Renewal: ACI does not permit renewal through continuing education units (CEUs), professional development hours (PDHs), or supervisor letters of experience.
Mandatory Re-examination: To maintain active certification, technicians must re-register, re-take, and pass both the complete written examination and the complete performance examination prior to their expiration date.
The Eight Core Standards Covered in Level 1
The entire ACI Aggregate Testing Technician Level 1 program is built upon eight foundational standards established by ASTM International (and their equivalent AASHTO counterparts). The following table details each standard, its title, primary testing role, and relative weight:
ASTM Standard AASHTO Equiv. Standard Title Primary Engineering Function Typical Exam Items
ASTM D75 / D75M AASHTO R 90 Standard Practice for Sampling Aggregates Establishes protocols for obtaining representative field samples from stockpiles, conveyor belts, bins, transportation units, and roadways. 8–12
ASTM C702 / C702M AASHTO R 76 Standard Practice for Reducing Samples of Aggregate to Testing Size Specifies the three standardized reduction techniques (mechanical splitter, quartering, miniature stockpile) to prevent segregation. 8–12
ASTM C117 AASHTO T 11 Standard Test Method for Materials Finer than 75-µm (No. 200) Sieve in Mineral Aggregates by Washing Separates and quantifies micro-fine clay, silt, and dust coatings adhering to aggregate particles, using plain water (Procedure A) or a wetting agent (Procedure B). 8–12
ASTM C136 / C136M AASHTO T 27 Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates Determines the particle size distribution (grading) of dry aggregates using standard nested sieves and mechanical agitation. 8–12
ASTM C127 AASHTO T 85 Standard Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate Measures relative density (OD, SSD, apparent) and absorption of aggregate retained on the 4.75-mm (No. 4) sieve. 8–12
ASTM C128 AASHTO T 84 Standard Test Method for Relative Density (Specific Gravity) and Absorption of Fine Aggregate Measures relative density and absorption of fine aggregate by the pycnometer or Le Chatelier flask procedure, with the cone-and-tamper test for SSD. 8–12
ASTM C566 AASHTO T 255 Standard Test Method for Total Evaporable Moisture Content of Aggregate by Drying Quantifies total internal and surface moisture by thermal drying to compute batch plant scale and water adjustments. 8–12
ASTM C40 / C40M AASHTO T 21 Standard Test Method for Organic Impurities in Fine Aggregates for Concrete Assesses deleterious organic compounds (humic acid, decayed vegetable matter) using sodium hydroxide colorimetric comparison. 8–12
Note
All eight standards carry the same item allowance. ACI publishes a single figure — approximately 100 multiple-choice questions with 8 to 12 questions on each standard . It does not weight C136 or C127 more heavily than D75 or C40. Because the 60% per-standard hurdle applies to every one of the eight blocks, the standard you find least interesting is worth exactly as much of your study time as the one you find hardest.
Open-Book Test Strategy & Practical Lab Tips
While an open-book exam may sound straightforward, it is one of the most common pitfalls for unprepared candidates. With 120 minutes to solve ~100 technical and mathematical questions , examinees have an average of 1.2 minutes (72 seconds) per question .
Strategic Workbook Tabbing
Candidates who flip through pages searching for basic definitions run out of time before completing the calculation-heavy sections (such as C136 grading or C127/C128 specific gravity). To maximize efficiency:
Color-Code Standard Tabs: Affix durable index tabs to the start of each ASTM standard in your CP-44 workbook.
Tab Critical Tables: Specifically tab the minimum field sample mass table in ASTM D75 , the minimum test specimen mass table in ASTM C136 , and the maximum allowable sieve overload table in ASTM C136 .
Tab Critical Formulas: Place reference tabs directly on the relative density formulas in ASTM C127/C128 , the C566 moisture equation, and the two places where ASTM and AASHTO wording diverges — the C136 / T 27 sieving-sufficiency percentage and the C127 / T 85 water-temperature tolerance.
Practical Performance Exam Tips
Master the Cone and Tamper Test (ASTM C128): The cone-and-tamper test for fine aggregate SSD requires tactile familiarity. Practice tamping exactly 25 times from 5 mm above the sand surface and observing the partial slumping behavior.
Verbalize Steps Clearly: When performing the test in front of the proctor, clearly speak each step out loud: "I am checking that the wash water is clear," or "I am ensuring the mechanical splitter has at least eight equal-width chutes for coarse aggregate." This ensures the examiner checks off every rubric item.
Verify Equipment Calibration: Always verify that balances are leveled, tared, and meet the readability required by the governing standard (e.g., 0.1 g vs 0.5 g vs 1.0 g).