ACI Study Guide 2026
Everything you need to pass the ACI exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 ACI Exam Format at a Glance
📚 ACI Topics to Study (69)
✍️ Sample ACI Questions & Answers
1. What is the purpose of the 'gradual cooling' recommendation after the cold-weather protection period ends?
Gradually reducing heat prevents rapid temperature differentials between the concrete surface and interior that could cause thermal shock cracking.
2. What does the term 'modulus of rupture' describe in concrete testing?
Modulus of rupture (MOR) is the flexural tensile strength determined by loading a concrete beam to failure per ASTM C78.
3. When is the use of a vapor retarder most critical under a concrete slab?
Vapor retarders are essential when the slab will support materials sensitive to moisture vapor transmission, such as vinyl tile, hardwood, or epoxy coatings.
4. Why is it important to cure concrete after finishing?
Curing retains moisture needed for cement hydration, ensuring concrete achieves its design strength and durability.
5. What is the primary cause of scaling on a concrete surface after the first winter?
Scaling results from a weakened surface layer caused by premature finishing over bleed water or early curing compound application, which is then damaged by freeze-thaw action.
6. Which placement method is preferred when placing concrete in a wall form that connects to a flatwork slab to prevent cold joints?
Monolithic placement or a properly prepared construction joint with bonding agent ensures structural continuity between a wall and slab without a weak cold joint.