Technical Questions

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




Question: Specialty admixtures

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

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

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

Question: What are set-controlling admixtures?

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

Question: What is an admixture?

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

Question: What is an air-entraining admixture?

Question: What are water-reducing admixtures?

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

Question: Commonly used accelerating admixture

Question: Do some water-reducing admixtures induce bleeding?

Question: Air content common limits

Question: Air tests for nonair-entrained concrete

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

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

Question: Factors affecting time of setting

Question: Resistance to cycles of freezing and thawing

Question: What factors affect the mixing time?

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

Question: Curling, shrinkage, and w/cm

Question: Using cube tests in lieu of cylinder tests

Question: Maximum temperature limits for hot-weather concreting

Question: Consistency, plastic consistency, and workability

Question: Heat of hydration and the importance of controlling it

Question: The effect of air content on concrete strength

Question: Epoxy-coated reinforcement

Question: The purpose of calcium sulfate (gypsum)

Question: The effect of pozzolans on water demand

Question: What fibers are used in concrete?

Question: How is workability measured and specified?

Question: Protecting concrete from cycles of freezing and thawing

Question: How do the requirements of placing affect the selection of proportions of aggregates and cementitious material?

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

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

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

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: What are the essential requirements of consistency?

Question: Why is consolidation needed?

Question: How does the temperature influence curing?

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

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

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

Question: Mixture design and strength submittals

Question: How to Control Mass Concrete Temperature during Construction


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