- Two Exams, Two Sets of Pass Rules
- The Written Exam Scoring Math: 60% Per Standard, 70% Overall
- What Each Standard Asks of You
- How the Performance Exam Is Scored
- What Happens If You Fail
- What It Costs to Take Each Attempt
- A Study Sequence Built Around the Passing Rules
- After You Pass: Five Years and a Full Retest
- Frequently Asked Questions
- The written exam requires at least 60% on each standard and at least 70% overall; both conditions must be met.
- The performance exam is separate, closed-book, and graded pass/fail on checklists covering all four procedures.
- Both exams must be passed within one year; after that window, both components must be retaken.
- The written exam is one hour, closed-book, multiple choice, with approximately 35-40 questions and 8-10 per standard.
Two Exams, Two Sets of Pass Rules
The Concrete Strength Testing Technician credential, administered by the American Concrete Institute (ACI) through approved Sponsoring Groups and resource centers, does not use a single score. You earn certification by passing two separate examinations, and each has its own standard of success:
- Written examination: a one-hour, closed-book, multiple-choice test scored against percentage thresholds.
- Performance examination: a closed-book practical in which an examiner watches you perform each procedure and grades you against a pass/fail checklist.
That split is the first thing to understand about "the passing score." There is no scaled score, no cut score that shifts from year to year, and no curve. The written exam has a transparent, published rule, and the performance exam is a checklist you either satisfy or do not. Candidates have one year to pass both. If you are still weighing the credential, our guide on how hard the CSTT exam is puts the two components in context, and the CSTT requirements guide covers eligibility, which has no specific education or work-experience prerequisite.
The Written Exam Scoring Math: 60% Per Standard, 70% Overall
The written exam is where candidates most often misunderstand the rule. ACI's passing requirement has two conditions, and you must satisfy both at once:
- At least 60% on each standard, and
- At least 70% overall.
Question count and distribution
The question count is described slightly differently in two ACI sources, so treat it as an approximation rather than a fixed number:
| Source | Approximate questions | Minimum per standard |
|---|---|---|
| Current ACI program page | About 40 | At least 8 |
| Certification Program Policy CPP 620.2-19 | About 35-40 | 8-10 |
With roughly 8-10 questions per standard, each individual question carries real weight in the per-standard calculation. On a standard with eight questions, the 60% floor means you need at least five correct (4.8 rounds up to five). With ten questions you need at least six. The lesson: do not treat any single standard as the one you can afford to skip, because a handful of misses concentrated in one area can sink an otherwise good attempt. For a fuller picture of how results have trended, see the CSTT pass rate analysis.
Key Takeaway
Aim for comfortable margin on every standard rather than excellence on three. A realistic personal target is to be answering well above the 60% floor on your weakest standard in practice tests, because exam-day nerves cost points on short, eight-to-ten-question sections.
What Each Standard Asks of You
The four exam areas map directly to four ASTM standards. According to ACI's Job-Task Analysis (approved February 29, 2020, editorially updated February 8, 2022), these are unweighted examination-objective areas, not four equally weighted domains. In practice, the written exam draws roughly the same number of questions from each. The program's technical basis is C617/C617M-15, C1231/C1231M-15, C39/C39M-18, and C78/C78M-18. For a deeper walkthrough, read our complete guide to the four CSTT content areas.
ASTM C617/C617M: Standard Practice for Capping Cylindrical Concrete Specimens
This standard covers preparing the ends of cylinders so load is applied evenly during compression testing.
- Know the capping materials and when each is appropriate.
- Understand end-surface planeness and perpendicularity requirements, and why poor capping produces artificially low strength results.
- Be able to explain timing and curing considerations for caps before testing.
ASTM C1231/C1231M: Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders
The alternative to bonded caps. Questions here test whether you know the conditions and limits of using unbonded caps.
- Understand the cap components and the restrictions on their reuse and condition.
- Know how unbonded-cap results relate to the acceptable testing situation and what disqualifies a setup.
- Be able to distinguish C1231 requirements from C617 requirements, since candidates often blur the two.
ASTM C39/C39M: Compressive Strength of Cylindrical Concrete Specimens
The core compression test and typically the most familiar procedure to working technicians.
- Know the loading rate requirements and how they affect measured strength.
- Understand specimen measurement, alignment in the machine, and the fracture patterns that indicate a valid or questionable break.
- Be fluent in the calculation of compressive strength from load and area, since simple non-programmable calculators are allowed.
ASTM C78/C78M: Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)
The beam test, which uses a different geometry and different calculations than cylinder work.
- Understand the third-point loading arrangement and the span and support requirements.
- Know where the fracture occurs relative to the loading points and how that location affects the modulus of rupture calculation.
- Practice the flexural strength formula, since this is the standard many field-oriented technicians use least often.
One practical observation: technicians who spend their days breaking cylinders often feel confident on C39 and underprepared on C78, C617, or C1231. Because every standard carries its own 60% floor, honest self-assessment about your weakest procedure is the most useful preparation you can do.
How the Performance Exam Is Scored
The performance examination is a closed-book practical that assesses all four procedures using pass/fail checklists. There is no percentage here. For each procedure, the examiner is looking for specific required steps performed correctly and in sequence. Missing a required step on a checklist can result in a failed procedure.
- It is closed book, so you must know the sequence and critical requirements from memory.
- Simple, non-programmable calculators are permitted for the calculation portions.
- A failed practical procedure allows a second trial on the same day.
Many ACI Sponsoring Groups bundle a review session with the exam. Whether you choose that route or study independently, make sure you get supervised practice on the equipment you will be examined with, since familiarity with the physical setup removes a common source of avoidable errors.
What Happens If You Fail
The retake rules are specific, and misunderstanding them is costly. According to ACI's Certification Program Policy CPP 620.2-19 and the current program page:
| Situation | What the policy allows |
|---|---|
| Fail one practical procedure | A second trial of that procedure on the same day |
| Fail a component after that | Subsequent re-examination covers the entire failed written or performance component, not just the part you missed |
| One-year window expires with a component unpassed | Both components must be retaken |
Two takeaways follow. First, the same-day second trial on a practical procedure is a genuine safety net, but it applies to the practical, so do not count on it for the written exam. Second, a re-examination means redoing the whole failed component. If you fail the written exam by missing the 60% floor on a single standard, you still retake the entire written exam, not just that standard.
Key Takeaway
Treat the one-year window as a real deadline. If you pass one component early, schedule the second promptly instead of letting the window run down, because missing it forces you to retake both examinations.
What It Costs to Take Each Attempt
Because exams are administered through ACI-approved Sponsoring Groups, there is no single national price. The figures below are verified local 2026 examples, not national tariffs, and they show how much the structure can vary by provider. Always confirm current pricing with your own Sponsoring Group. Our CSTT certification cost breakdown goes deeper on budgeting.
| Provider | What is included | Member price | Non-member price |
|---|---|---|---|
| Las Vegas Chapter | Certification/recertification including workbook, review, and both exams (optional training excluded) | USD 475 | USD 550 |
| Las Vegas Chapter | Optional training | USD 225 | USD 300 |
| Las Vegas Chapter | Failed-component retest | USD 235 | USD 290 |
| Ohio Concrete | Full exam-only | USD 330 | USD 490 |
| Ohio Concrete | Review, workbook, and exams | USD 450 | USD 700 |
Note that the Ohio Concrete prices reflect Ohio Concrete membership, not ACI membership rates. The Las Vegas Chapter listed an October 24, 2026 session. For other regions, see our CSTT exam dates and scheduling guide.
The failed-component retest fee is the number that makes the passing rules concrete. A single below-floor standard on the written exam can mean paying for a full retest, so preparing to clear the 60% threshold on every standard is also a financial decision.
The workbook
The current study workbook is CP-19, 25th Edition (2022). ACI also accepts the 23rd and 24th editions because their technical basis is identical. The 25th-edition workbook excludes the ASTM standards themselves and is listed at USD 71 for ACI members or USD 136 for non-members. ACI notes first-printing errata exists, but the linked document requires sign-in, so check it if you use an early printing. ACI also sells a separate on-demand preparation course, but it does not award certification.
A Study Sequence Built Around the Passing Rules
Because the 60% per-standard floor punishes uneven preparation, the sequence below deliberately spends the most time on the standards candidates tend to know least. It assumes about four weeks and should be adjusted to your own baseline. For a broader plan, see the CSTT study guide.
Baseline and the two capping standards
- Take a diagnostic practice test to find your weakest standard.
- Study C617/C617M and C1231/C1231M together, then contrast them side by side.
Compression testing (C39/C39M)
- Drill loading rates, specimen measurement, fracture patterns, and the strength calculation.
- Rehearse the full procedure aloud, step by step.
Flexural testing (C78/C78M)
- Work the third-point loading setup and the modulus of rupture calculation repeatedly.
- Spend extra time here if beams are not part of your daily work.
Integration and timed practice
- Take timed, closed-book practice sets, checking that each standard stays comfortably above 60%.
- Run each performance procedure end to end without notes.
Use the practice questions on our CSTT practice test site to measure each standard separately instead of relying on one blended score, and keep a quick reference like the CSTT cheat sheet for final review.
After You Pass: Five Years and a Full Retest
Certification lasts five years. Recertification is not a paperwork renewal: it requires passing both the written and performance examinations again. That makes the credential a periodic proof of competence rather than a one-time achievement, which is worth factoring into long-term planning. If you are weighing the investment, our analyses of whether the CSTT certification is worth it, the earnings picture, and CSTT jobs cover what the credential can mean for your career.
Frequently Asked Questions
You need at least 60% on each standard and at least 70% overall. Both conditions must be met, so a high overall score does not save an attempt if any single standard falls below 60%.
ACI describes it as approximately 35-40 questions in the policy document and about 40 on the current program page, with roughly 8-10 per standard. Treat the count as an approximation rather than a fixed number. The exam is one hour, closed book, and multiple choice.
No. The performance exam is graded on pass/fail checklists across all four procedures. If you fail a practical procedure, you may make a second trial on the same day.
You have one year to pass both the written and performance examinations. Re-examination covers the entire failed component, and if the one-year window passes, both components must be retaken.
Certification lasts five years. Recertification requires passing both the written and performance examinations again.
Knowing the exact passing rules turns preparation into a targeted plan: clear the floor on every standard, rehearse each procedure until the checklist is automatic, and use the CSTT passing score reference alongside the practice test to track your readiness before exam day.