Frequently Asked Questions

In This Section

Other Sources for Answers

Search other resources on the ACI website for answers to technical questions

Technical Questions

ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics.



Found 49 FAQs.

Question: Specialty admixtures

Question: What does ACI recommend regarding water-cement (w/c) ratios or admixtures to improve workability...

Question: How do fibers affect the workability of concrete? Do fibers require additional water for placement?

Question: Maximum temperature limits for hot-weather concreting

Question: Air tests for non-air-entrained concrete

Question: Would adding more cement serve the purpose of admixtures?

Question: What fibers are used in concrete?

Question: The effect of entrained air on the workability of concrete

Question: Do different admixtures of a given type always perform the same?

Question: How can it be determined that an admixture will serve its intended purpose?

Question: Epoxy-coated reinforcement

Question: Are retarding admixtures reliable as to the time of setting?

Question: Are epoxy resins widely used in concrete construction and repair?

Question: What is an admixture?

Question: What are set-controlling admixtures?

Question: Commonly used accelerating admixture

Question: Definition of concrete, hydraulic cement, mortar, and grout

Question: How are the relatively small dosages of an admixture measured reliably and placed in the mixer?

Question: Mixture design and strength submittals

Question: Heat of hydration and the importance of controlling it

Question: Consistency, plastic consistency, and workability

Question: The effect of air content on concrete strength

Question: The effect of water-reducing admixtures on drying shrinkage

Question: How is workability measured and specified?

Question: What allowance should be made for strengths where air-entrained concrete is to be used?

Question: Why is consolidation needed?

Question: What are water-reducing admixtures?

Question: How to Control Mass Concrete Temperature during Construction

Question: Using cube tests in lieu of cylinder tests

Question: What is an air-entraining admixture?

Question: What methods are used for protecting concrete against low temperatures?

Question: Resistance to cycles of freezing and thawing

Question: Do some water-reducing admixtures induce bleeding?

Question: Protecting concrete from cycles of freezing and thawing

Question: The effect of pozzolans on water demand

Question: Curling, shrinkage, and w/cm

Question: Air content common limits

Question: Factors affecting time of setting

Question: How do the requirements of placing affect the selection of proportions of aggregates and cementi...

Question: What is the basis of proportioning to ensure concrete of the desired weather resistance?

Question: How should the aggregates and other ingredients be measured to obtain uniformity in proportions?

Question: When is the slump test useful in detecting changes in the concrete?

Question: The purpose of calcium sulfate (gypsum)

Question: How is the selection of mixture proportions affected by the materials to be used and the placing...

Question: What factors affect the mixing time?

Question: How does the temperature influence curing?

Question: What are the essential requirements of consistency?

Question: How is the water-cementitious material ratio (w/cm) expressed?

Question: When does the slump test provide a useful indication of workability?