What Is ACI-AGGREGATE-L1?

What ACI-AGGREGATE-L1 Actually Is

ACI-AGGREGATE-L1 is the American Concrete Institute's Aggregate Testing Technician-Level 1 credential. In ACI's own program documentation it is internally abbreviated ATT1, but the site key used across reference material - including here - is ACI-AGGREGATE-L1. It exists to verify that a technician can correctly sample, reduce, sieve, wash, and analyze aggregate materials according to a defined set of AASHTO and ASTM test methods used in concrete and construction materials testing.

This is a hands-on, procedure-driven credential rather than a management or design certification. Someone holding it has demonstrated - under observation - that they can run the specific tests aggregate testing labs, DOTs, and construction materials firms rely on every day.

Who Administers and Grades the Exam

ACI-AGGREGATE-L1 testing is delivered through approved sponsoring groups - local chapters, testing organizations, and training providers - with ACI examiners and proctors running the sessions. ACI itself grades the results. Written retests carry a bit more flexibility: eligible candidates can also sit for a written retest through Prometric rather than waiting for another in-person sponsor session.

The governing policy document, CPP 620.3-25, was most recently revised May 16, 2025, and it sets the administrative rules examiners and sponsors follow. The underlying job-task analysis that defines what the exam actually covers was approved September 21, 2020, with minor editorial corrections made October 19, 2021. That job-task analysis is the real source of the eight domains discussed below.

Eligibility: No Prerequisites Required

Unlike many technical certifications that require documented work hours or a minimum education level before you can even sit for the exam, ACI-AGGREGATE-L1 has no specific education or work-experience prerequisites. Anyone can register for a session through an approved sponsor.

That openness is a double-edged sword. It removes the paperwork barrier, but it also means the exam itself has to do all the filtering - which is part of why the performance component is so strict. For a fuller breakdown of what "no prerequisites" does and doesn't mean in practice, see ACI-AGGREGATE-L1 Requirements 2026: Eligibility, Prerequisites & How to Qualify.

Exam Format: Written and Performance Components

ACI-AGGREGATE-L1 certification requires passing two distinct components, and both must be completed within one year of each other.

The Written Examination

The written exam is open-book, but only ACI-approved references may be used at the table - you can't bring in arbitrary notes or outside textbooks. It runs on a two-hour time limit and contains approximately 100 multiple-choice questions pulled from the eight standard areas below. Approved simple-function, nonprogrammable calculators are allowed; a phone or tablet calculator app is not permitted as a substitute.

Scoring is two-layered: you need at least 60% on each required standard individually, and at least 70% overall across the whole exam. That means you can't compensate for a weak domain by acing the others - every standard has its own floor. For the exact mechanics of this dual threshold, see ACI-AGGREGATE-L1 Passing Score 2026: Exactly What You Need to Pass.

The Performance Examination

The performance exam is closed-book and evaluated by an examiner watching you physically run the procedures. You must successfully complete every required procedure - there's no partial credit averaged across tasks the way there is on the written side. Verbal description of a step is only accepted where the policy explicitly permits it; otherwise you have to physically perform the action.

One detail candidates frequently get wrong: the performance exam does not have a single 30-minute cap for the entire session. Instead, performance calculation worksheets individually carry a maximum of 30 minutes each. Confusing the two can cause candidates to rush procedures unnecessarily.

The Eight AASHTO/ASTM Domains

The job-task analysis behind ACI-AGGREGATE-L1 organizes content into eight paired AASHTO/ASTM standard areas. These aren't loosely themed "topics" - they are the specific test methods you'll be examined on, both in multiple-choice form and physically at the bench.

For a deeper walkthrough of what examiners actually probe within each of these eight areas, see the ACI-AGGREGATE-L1 Exam Domains 2026: Complete Guide to All 8 Content Areas. If you're trying to gauge how tough the combined written-and-performance format really is relative to other certifications, How Hard Is the ACI-AGGREGATE-L1 Exam? Complete Difficulty Guide 2026 walks through that comparison in detail.

Study Materials and Fee Mechanics

The official program workbook is CP-44, eighth edition. It's worth noting explicitly that CP-44 includes the AASHTO standards, not the ASTM texts - if your lab or training program uses ASTM-numbered references day to day, don't assume the workbook mirrors that numbering exactly. As of a September 10, 2026 pricing check, ACI lists CP-44 at $138 for non-members and $72 for ACI members.

Session and testing fees are set independently by each sponsoring group, not by ACI centrally. As one dated example: Central Texas ACI's September 12, 2026 session in Pflugerville listed $675 for full certification, $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 figures. These numbers are specific to that sponsor and that session; other approved sponsors set their own local pricing.

Because fees vary by sponsor and location, treat the table above as an illustration of typical fee structure rather than a national price. For a wider breakdown of how these costs stack up against workbook purchases and potential retests, see ACI-AGGREGATE-L1 Certification Cost 2026: Complete Pricing Breakdown.

Certification Validity and Renewal

Once earned, ACI-AGGREGATE-L1 certification is valid for five years. Renewal is not a paperwork-only formality - it requires retaking both the written and performance examinations again, the same as initial certification. This structure keeps certified technicians current on procedure details rather than relying on a credential earned once and never re-verified.

If you're mapping out when to schedule a session relative to sponsor calendars, ACI-AGGREGATE-L1 Exam Dates 2026: Testing Windows, Deadlines & Scheduling covers how testing windows are typically organized by sponsors.

Who Pursues This Certification

ACI-AGGREGATE-L1 is aimed at technicians who physically run aggregate testing in the field or in a lab setting - commonly employed by materials testing and inspection firms, ready-mix and aggregate producers, state and local transportation departments, and construction quality-control programs. Because the credential centers on AASHTO/ASTM procedures tied to concrete materials, it's frequently listed as a preferred or required qualification on job postings for aggregate lab technician and materials inspector roles.

If you're evaluating whether pursuing this specific credential fits your career path, ACI-AGGREGATE-L1 Jobs and Is the ACI-AGGREGATE-L1 Certification Worth It? Complete ROI Analysis 2026 both dig into how the credential is actually used on the job market. For a broader look at earnings context tied to this specific certification, see ACI-AGGREGATE-L1 Salary Guide 2026: Complete Earnings Analysis.

Preparing Around the Domain Structure

Because passing requires clearing a 60% floor on each of the eight standard areas individually, a study plan built around equal exposure to every domain works better than one that leans heavily on your strongest procedures. A simple way to sequence review across the weeks before a session:

Practicing under realistic multiple-choice conditions matters as much as memorizing the procedures. You can run timed question sets on the main practice test platform to get a feel for the two-hour pace before sitting for the real written exam. A more detailed week-by-week strategy, including how to layer in performance-exam rehearsal, is available in the ACI-AGGREGATE-L1 Study Guide 2026: How to Pass on Your First Attempt.

Frequently Asked Questions