Email Address is required Invalid Email Address
In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Learn More
Become an ACI Member
Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
Staff Directory
ACI World Headquarters 38800 Country Club Dr. Farmington Hills, MI 48331-3439 USA Phone: 1.248.848.3800 Fax: 1.248.848.3701
ACI Middle East Regional Office Second Floor, Office #207 The Offices 2 Building, One Central Dubai World Trade Center Complex Dubai, UAE Phone: +971.4.516.3208 & 3209
ACI Resource Center Southern California Midwest Mid Atlantic
Feedback via Email Phone: 1.248.848.3800
Home > Tools > Frequently Asked Questions
Question: ACI code for evaluating existing buildings prior to repair
Question: Maximum temperature limits for hot-weather concreting
Question: Size of test cylinder
Question: Standards for 7-day and 28-day strength test results
Question: Definition of concrete, hydraulic cement, mortar, and grout
Question: How is the required strength selected, measured, and obtained?
Question: Legacy building codes
Question: Determining the cause of a crack
Question: Tolerances for floors supporting operable partitions
Question: What procedure should be followed for standard curing of specimens for strength tests?
Question: Could a sulfate-resisting cement and slag cement be combined and used for concrete exposed to su...
Question: How can durable aggregates be ensured?
Question: Low-strength cylinder test results
Question: What is a pozzolan?
Question: The effect of pozzolans on water demand
Question: What fibers are used in concrete?
Question: Improving the abrasion resistance of concrete
Question: Curing Cylinders for Acceptance Testing
Question: Rebound hammer and in-place strength testing
Question: Standard on detailing of concrete reinforcement
Question: Using cube tests in lieu of cylinder tests
Question: Why is Type IV cement rarely produced and Type V cement rarely used?
Question: The effect of maximum size of aggregate on concrete strength
Question: What are the ultrasonic pulse velocity and the pulse echo tests?
Question: Tolerances for concrete slabs supporting steel tanks
Question: The effect of pozzolans on shrinkage
Question: Requirements for storing and handling aggregate
Question: Aggregate classification by density
Question: What is meant by properly cured concrete?
Question: Air tests for non-air-entrained concrete
Question: Using core strength to calculate compressive strength of an existing structure
Question: What is slag cement or ground granulated blast-furnace slag (GGBFS)
Question: Benefits of using slag cement
Question: What does a pozzolan do in the concrete?
Question: Using and handling pozzolans
Question: Importance of using pozzolans in hydraulic and environmental structures
Question: Are pozzolans all alike?
Question: What is fly ash?
Question: What are blended cements?
Question: What is aggregate?
Question: The effect of aggregate shape on concrete strength
Question: The effect of aggregate grading on concrete strength
Question: The effect of aggregate strength on concrete strength
Question: The effect of aggregate characteristics on concrete shrinkage and permeability
Question: What is an admixture?
Question: What is an air-entraining admixture?
Question: The most important single factor affecting compressive strength
Question: What are rebound, penetration resistance, and pullout tests?
Question: How is the shrinkage of concrete determined?
Question: Curing Test Specimen at High Temperatures
Question: Estimating in-place concrete strength
Question: Standard specifications for cements
Question: Do all fly ashes behave in a similar way?
Question: What is silica fume?
Question: Why is combined aggregate grading used?
Question: The effect of aggregate on concrete durability
Question: What are water-reducing admixtures?
Question: What are set-controlling admixtures?
Question: Are retarding admixtures reliable as to the time of setting?
Question: Why is the workability of concrete important?
Question: How is workability measured and specified?
Question: When does the slump test provide a useful indication of workability?
Question: What test is available to evaluate the behavior of no-slump concrete as it is vibrated?
Question: Why are many non-destructive tests used as “estimators” of concrete strength?
Question: How is strength estimated by the maturity method?
Question: How is the resistance to alkali-aggregate reaction (AAR) determined?
Question: Air content common limits
Question: Factors affecting cement properties
Question: What are shrinkage-compensating expansive cement and concrete?
Question: Can you use any source of water as mixing water?
Question: What are high-density aggregates?
Question: Important requirements of a concrete aggregate
Question: Characteristics of aggregate affecting concrete strength
Question: The effect of surface texture and cleanness on concrete strength
Question: How can it be determined that an admixture will serve its intended purpose?
Question: Are there any tests that may be made directly on the structure to determine if the concrete has ...
Question: How is the temperature of concrete measured?
Question: What test conditions affect the results of compressive strength tests of concrete?
Question: Is pulse velocity related to strength?
Question: What other uses are there for the pulse velocity?
Question: How is the permeability of concrete determined?
Question: Definition of setting time
Question: The difference between setting and hardening
Question: Measurement of setting time
Question: False and flash set
Question: Strength of concrete
Question: Factors affecting permeability
Question: The relationship between porosity and permeability of concrete
Question: The purpose of calcium sulfate (gypsum)
Question: Effects of cement fineness on cement properties
Question: Unsoundness in portland cement
Question: The cause of false set
Question: Characteristics of cement that affect compressive strength
Question: Do different admixtures of a given type always perform the same?
Question: How are the relatively small dosages of an admixture measured reliably and placed in the mixer?
Question: Do some water-reducing admixtures induce bleeding?
Question: How can the adequacy of mixing be determined?
Question: How can the surface or free water carried by the aggregates be determined?
Question: How is the slump test made?
Question: Why is the slump test not an absolute measure of consistency or workability?
Question: When is the slump test useful in detecting changes in the concrete?
Question: How is the resistance to sulfate determined?
Question: How is the abrasion resistance of concrete determined?
Question: Curing and curling of concrete slabs over vapor retarders
Question: How is the air content of hardened concrete determined?
Search other resources on the ACI website for answers to technical questions