CSTT Certification

What the Concrete Strength Testing Technician Certification Actually Is

The Concrete Strength Testing Technician (CSTT) credential verifies that a person can correctly prepare and break concrete specimens in a laboratory setting. It is narrower than many people expect. It does not cover sampling fresh concrete in the field, slump testing, air content or unit weight. Those belong to other ACI programs. If you are new to the acronym itself, our explainers on what CSTT certification is and what CSTT stands for cover the basics.

Instead, the certification centers on the work that happens after cylinders and beams arrive at the lab: capping cylinders, using unbonded caps, loading cylinders to failure for compressive strength, and breaking simple beams for flexural strength. A technician who holds this credential is expected to follow the governing ASTM procedures closely enough that the reported strength reflects the concrete rather than the testing technique.

Who Issues It and How Exams Are Delivered

The certification is issued through the American Concrete Institute (ACI). Examinations are not taken at a single national testing center. They are administered through ACI-approved Sponsoring Groups and resource centers, which are typically local ACI chapters, industry associations and training organizations. Each sponsor sets its own session calendar, location, bundling options and pricing, which is why the cost and schedule details later in this article differ from one provider to the next.

Practically, this means your first task is finding a sponsor near you that is running a Concrete Strength Testing Technician session. Our guide to CSTT exam dates and scheduling explains how to approach that search, and the CSTT requirements overview covers the administrative side in more depth.

Eligibility: No Prerequisites, But a One-Year Clock

ACI does not set a specific education or work-experience prerequisite for this certification. You do not need a degree, a minimum number of lab hours or an existing credential to register. That openness is part of why the program is popular as an entry credential for new lab hires.

The constraint that matters is time. Candidates must pass both the written and performance examinations within one year. If you pass one component and then let a year lapse before passing the other, you will have to retake both. Plan your sessions so that the written and performance components fall close together, ideally on the same day if your sponsor offers that format.

Inside the Written Examination

The written exam is one hour long, closed book and multiple choice. The question count is described slightly differently in two official places. The current program page describes approximately 40 questions with at least eight per standard, while Certification Program Policy CPP 620.2-19 describes approximately 35 to 40 questions with 8 to 10 per standard. The safest way to prepare is to treat the count as approximate and expect roughly eight to ten questions on each of the four standards.

That distribution is the most important structural fact about the written exam. Because questions are spread across all four standards, you cannot compensate for a weak area by being excellent in another. Skipping one standard is not a viable strategy, as the scoring rules below make clear.

Questions tend to test procedural recall: required tolerances, loading rates, curing and conditioning requirements, specimen measurement, and what makes a result invalid or a test non-compliant. For a sense of how this compares to other technician exams, see how hard the CSTT exam is.

Inside the Performance Examination

The performance examination is separate from the written test and is also closed book. An examiner observes you performing the procedures for all four standards and scores each against a pass/fail checklist. The checklist format matters: it rewards completing every required step in the proper way, not merely producing a plausible strength number.

Simple, non-programmable calculators are permitted. That is enough for the arithmetic involved, such as converting a failure load and measured diameter into a compressive strength, or computing modulus of rupture from beam dimensions and break load.

The Four Objective Areas, Standard by Standard

The four headings below come from ACI's Job-Task Analysis for this certification, approved February 29, 2020 and editorially updated February 8, 2022. They are unweighted examination-objective areas for both the written and performance exams. They are not four equally weighted domains, so do not assume each represents exactly one quarter of any score. The current technical basis is C617/C617M-15, C1231/C1231M-15, C39/C39M-18 and C78/C78M-18. For a broader walkthrough, read our complete guide to the four CSTT content areas.

Scoring Rules and Retake Mechanics

The written exam has a two-part pass requirement. You must score at least 60% on each standard and at least 70% overall. Both conditions apply at once. A candidate who scores very well overall but falls below 60% on one standard does not pass the written exam. Our CSTT passing score guide walks through the arithmetic, and the CSTT pass rate discussion explains why published figures should be treated carefully.

If you fail, re-examination covers the entire failed component, written or performance, not just the portion you missed. And if the one-year completion window expires before you have passed both, both components must be retaken. This is another reason to schedule the two exams together rather than spacing them out.

Fees: What Local Pricing Looks Like

There is no single national price, because each Sponsoring Group sets its own. The figures below are verified local 2026 examples, not national tariffs, and are included to show how the structure varies. Always confirm current pricing with the sponsor you plan to use. For broader context, see our CSTT certification cost breakdown.

The CP-19 Workbook and Preparation Materials

The current study workbook is CP-19, 25th Edition (2022). ACI also accepts the 23rd and 24th editions, because their technical basis is identical, which can matter if you are borrowing a coworker's copy. The 25th-edition workbook is listed at USD 71 for ACI members and USD 136 for non-members. It excludes the ASTM standards themselves, so reading the standards is a separate task.

ACI identifies errata for the first printing, but the linked errata document requires sign-in, so check it if you own an early copy. One caution: ACI also sells a separate on-demand preparation course. It is useful for learning the material, but it does not award certification. Only passing both examinations does.

Pair the workbook with a structured plan. Our CSTT study guide and one-page CSTT cheat sheet are good companions, and the CSTT practice tests let you rehearse the multiple-choice format under time pressure.

A Domain-Ordered Preparation Plan

Because the practical exam follows the physical sequence of lab work, it helps to study in the same order the work happens: capping first, then compression, then flexure.

The per-standard tracking in Week 4 is deliberate. The 60% floor on each standard means your weakest standard, not your average, is what puts you at risk.

Five-Year Validity and Recertification

Certification lasts five years. Recertification is not a paperwork renewal: it requires passing both the written and performance examinations again. Plan for that well before your expiration date, since sponsor sessions are scheduled periodically rather than on demand.

For career context, the credential matters most to employers that run or depend on concrete testing labs, such as commercial testing and inspection firms, ready-mix producers' quality-control labs, precast operations and contractors with in-house testing. See our pages on CSTT jobs, the CSTT salary guide and whether the certification is worth it for a closer look at the payoff.

Frequently Asked Questions