Technical Questions

Question: Mixture design and strength submittals

Question: What is involved in the process of mixture proportioning?

Question: A fiber manufacturer uses a proprietary design method. How can the validity of this method be co...

Question: ACI code for evaluating existing buildings prior to repair

Question: How should the appropriate fiber be selected for a specific application, and how is fiber dosage...

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

Question: Reinforced concrete vs. prestressed concrete

Question: How does the relative amount of each ingredient used in concrete influence the properties of con...

Question: Are the proportions of ingredients inter-related to produce concrete of a given workability?

Question: The basic approach used in the ACI mixture proportioning method

Question: Does additional curing improve the properties of concrete in other ways than in strength?

Question: Determining the cause of a crack

Question: Low-strength cylinder test results

Question: Improving the abrasion resistance of concrete

Question: What steps are taken in the repair of concrete structures?

Question: What is shotcrete and when is it used?

Question: How are properties of concrete in the structure measured?

Question: Consolidation of concrete—required or not?

Question: Where is fiber-reinforced concrete mostly used in practice?

Question: Standards for 7-day and 28-day strength test results

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

Question: The effect of changes in proportions of the fine and coarse aggregate or the quantity of cementi...

Question: When heated enclosures are used to protect freshly placed concrete, what precautions are necessary?

Question: What methods of capping are recommended for compression specimens?

Question: Form release agents

Question: Curing Cylinders for Acceptance Testing

Question: Tolerances for floors supporting operable partitions

Question: When should saw cuts be made on a concrete slab?

Question: What properties of concrete are enhanced by the addition of fiber?

Question: Estimating in-place concrete strength

Question: The importance of proper drainage

Question: Characteristics of cement that affect compressive strength

Question: The ultimate objective in proportioning concrete

Question: If time is not available for preliminary tests, how can the desired strengths be ensured?

Question: What procedure should be followed for standard curing of specimens for strength tests?

Question: How to Control Mass Concrete Temperature during Construction

Question: Embedded metals other than reinforcing steel

Question: What are the primary benefits of using fiber-reinforced concrete compared to traditionally reinf...

Question: Requirements for durable concrete

Question: Evaluating the properties of hardened concrete

Question: Other important properties of concrete

Question: Epoxy-coated reinforcement

Question: Materials used to produce portland cement

Question: Factors affecting cement properties

Question: What are blended cements?

Question: What fibers are used in concrete?

Question: Protecting against excessive expansion due to alkali-aggregate reaction (AAR)

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

Question: How can segregation of the concrete between the mixer and its final point of placement be prevented?

Question: Is storing the specimens on the structure always a satisfactory procedure for estimating in-plac...

Question: Why are many non-destructive tests used as “estimators” of concrete strength?

Question: Acceptable concrete cracking

Question: Minimum concrete cover for balconies with PT cables

Question: Resistance to cycles of freezing and thawing

Question: Why is Type IV cement rarely produced and Type V cement rarely used?

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

Question: Who selects the requirements for concrete for a project?

Question: How is the required strength selected, measured, and obtained?

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

Question: What is meant by properly cured concrete?

Question: Do we always need to repair cracked concrete?

Question: How should samples of freshly mixed concrete be taken in the field to provide information on con...

Question: Aggregate blending

Question: Why are fibers used in concrete?

Question: Why might fibers “ball up” in concrete mixes?

Question: Are there any challenges or common issues encountered during the testing of fiber-reinforced con...

Question: Knowledge of concrete properties

Question: The importance of concrete cover

Question: Standard specifications for cements

Question: Requirements for storing and handling aggregate

Question: Specialty admixtures

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

Question: Are there data relating w/cm to flexural strength that are as reliable as those for compressive ...

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

Question: Is personal protection needed when handling concrete?

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

Question: Can the importance of proper consistency for placing be overemphasized?

Question: Can the heat liberated by the hydrating cement be relied on to give protection during cold weather?

Question: Can trial mixtures be made with full-size batches at the start of a job?

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

Question: Alternative methods for measuring crack width

Question: Simplified design for reinforced concrete buildings

Question: Curing and curling of concrete slabs over vapor retarders

Question: Can fresh concrete be used around aluminum framing or in aluminum molds??

Question: Will the use of fibers impact the compressive strength of the concrete?

Question: Does incorporating fiber as an alternative to traditional reinforcement enhance the environmenta...

Question: Factors affecting permeability

Question: Definition of portland cement

Question: Effects of cement fineness on cement properties

Question: Notable changes in modern portland cement properties

Question: What water-cementitious material ratio should be used for a particular job when strength require...

Question: When can the finishing procedure be started?

Question: What is the effect of freezing on concrete?

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

Question: Will concrete continue to increase in strength if there is no moisture present?

Question: What test conditions affect the results of compressive strength tests of concrete?

Question: Joint deterioration mechanism and prevention

Question: What is the difference between synthetic microfibers and macrofibers?

Question: How does the type of fiber (material, shape, and form) impact the design methodology used for fi...

Question: Will fiber-reinforced concrete have a hairy appearance?

Question: How does the testing methodology for fiber-reinforced concrete differ from that of traditional c...

Question: Using core strength to calculate compressive strength of an existing structure

Question: The effect of air content on concrete strength

Question: What is reinforced concrete?

Question: Advantages of low-density aggregate

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

Question: What nominal maximum sizes of aggregate are recommended?

Question: How is concrete placed?

Question: Why is consolidation needed?

Question: How should the concrete be consolidated to obtain a complete filling of the forms and around the...

Question: Does over-vibration cause segregation and loss of air content?

Question: When is steam curing used?

Question: Are polymer concrete and polymer-modified concrete used in repairs?

Question: Increasing the load capacity of a slab-on-ground using an overlay

Question: Epoxy-coated reinforcement and cover depth against ground

Question: What is the difference between corrected and uncorrected weight in a concrete mix design?

Question: What are the test methods used for evaluating fiber-reinforced concrete?

Question: Maximum temperature limits for hot-weather concreting

Question: Consistency, plastic consistency, and workability

Question: Definition of setting time

Question: The purpose of calcium sulfate (gypsum)

Question: Benefits of using slag cement

Question: What are shrinkage-compensating expansive cement and concrete?

Question: How can durable aggregates be ensured?

Question: What is an admixture?

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

Question: Commonly used accelerating admixture

Question: Protecting concrete from cycles of freezing and thawing

Question: The most important single factor affecting compressive strength

Question: Why is a plastic consistency usually desirable for placing concrete?

Question: How is concrete consolidated?

Question: What is the purpose of finishing and texturing concrete surfaces?

Question: What methods are commonly used to ensure sufficient moisture for curing concrete?

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

Question: Are load tests on completed structures ever employed?

Question: What is calcium-aluminate cement?

Question: Why use fiber-reinforced concrete?

Question: What is minimum reinforcement for crack-width control and how is design accomplished using fiber?

Question: Slabs-on-ground

Question: Strength of concrete

Question: The effect of pozzolans on shrinkage

Question: What is silica fume?

Question: The effect of aggregate shape on concrete strength

Question: The effect of aggregate grading on concrete strength

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

Question: Why is the workability of concrete important?

Question: How is workability measured and specified?

Question: Precautions against sulfate attack

Question: What consideration should be given to water that may be lost from concrete between the time it l...

Question: What factors affect the mixing time?

Question: What range in slump is recommended for various types of construction?

Question: How can the effectiveness of curing be measured?

Question: What tests are necessary or desirable in making a series of trial mixtures to arrive at a suitab...

Question: How is the air content of freshly mixed concrete determined?

Question: What are rebound, penetration resistance, and pullout tests?

Question: Could a sulfate-resisting cement and slag cement be combined and used for concrete exposed to su...

Question: Difference between a contraction joint, isolation joint, expansion joint, construction joint, an...

Question: Standard on detailing of concrete reinforcement

Question: Is chiseled concrete a common technique for facades

Question: How do fibers work?

Question: How do you mix fibers into concrete?

Question: Hardening of hydraulic cement

Question: Aging of concrete

Question: Factors affecting time of setting

Question: Air content common limits

Question: The effect of joints on the durability of concrete structures

Question: The earliest use of portland cement

Question: Unsoundness in portland cement

Question: The cause of false set

Question: What is slag cement or ground granulated blast-furnace slag (GGBFS)

Question: Importance of using pozzolans in hydraulic and environmental structures

Question: What is fly ash?

Question: Can you use any source of water as mixing water?

Question: What is an air-entraining admixture?

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

Question: What is the intention of the ACI 318 Building Code?

Question: What correction should be made for absorbed water and surface water carried by the aggregates?

Question: What are the essential requirements of consistency?

Question: What is curing?

Question: Is density a good indicator of air content?

Question: Popouts or popoffs?

Question: What is autogenous shrinkage?

Question: What is D-cracking?

Question: What is an expansive cement and what are the different types of expansive cement?

Question: Two-way slabs design, ACI 318 vs. FEM

Question: Guidance on designing reinforced concrete retaining walls

Question: Reinforcement termination in wastewater concrete containment

Question: Placement of welded wire reinforcement (WWR) in a slab-on-ground

Question: Tolerances for concrete slabs supporting steel tanks

Question: Shear Design Provisions in ACI 318-19

Question: How is reinforced concrete designed using fibers instead of traditional steel?

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

Question: What is mass concrete?

Question: Requirements for a successful concrete structure

Question: The difference between setting and hardening

Question: False and flash set

Question: The relationship between porosity and permeability of concrete

Question: The making of portland cement

Question: What is a pozzolan?

Question: The effect of pozzolans on freezing and thawing resistance

Question: Do all fly ashes behave in a similar way?

Question: Why is combined aggregate grading used?

Question: What are high-density aggregates?

Question: Characteristics of aggregate affecting concrete strength

Question: The effect of surface texture and cleanness on concrete strength

Question: The effect of maximum size of aggregate on concrete strength

Question: What are water-reducing admixtures?

Question: What are set-controlling admixtures?

Question: Do some water-reducing admixtures induce bleeding?

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

Question: Precautions to resist acid attack

Question: Definition of controlled low-strength material (CLSM)

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

Question: How can the adequacy of mixing be determined?

Question: Can you have too much paste or mortar?

Question: What is yield?

Question: How does the temperature influence curing?

Question: What is the importance of curing on strength?

Question: Are there any tests that may be made directly on the structure to determine if the concrete has ...

Question: Can tests be conducted by anyone?

Question: Does a wet specimen test higher than a dry one?

Question: Is pulse velocity related to strength?

Question: How is strength estimated by the maturity method?

Question: Curling, shrinkage, and w/cm

Question: Governing version of ACI 318

Question: Legacy building codes

Question: Load factors used in the 1963 building code

Question: Design Properties of Lightweight Concrete

Question: Predicating Temperature for Mass Concrete

Question: Rebound hammer and in-place strength testing

Question: Chloride concentration in soil and exposure classes

Question: What is the minimum fiber dosage? Is it possible to use less than the minimum dosage?

Question: Does the color or finish of fiber-reinforced concrete differ from regular concrete?

Question: Using cube tests in lieu of cylinder tests

Question: Air tests for non-air-entrained concrete

Question: Size of test cylinder

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

Question: Measurement of setting time

Question: Heat of hydration and the importance of controlling it

Question: Factors governing the strength of concrete

Question: The importance of reinforcement in concrete

Question: Definition of low-density concrete

Question: Definition of “hot cement”

Question: What does a pozzolan do in the concrete?

Question: Pozzolans in mass concrete

Question: Are pozzolans all alike?

Question: The effect of pozzolans on water demand

Question: What is a natural pozzolan?

Question: What is aggregate?

Question: Important requirements of a concrete aggregate

Question: The effect of aggregate on concrete durability

Question: The effect of aggregate strength on concrete strength

Question: If the cementitious material paste is not sufficient in amount to float all of the aggregate par...

Question: What is the importance of consolidation on strength?

Question: Is there any measure of the completeness or adequacy of curing?

Question: How much water goes into combination with the cement during the hardening of concrete?

Question: Are any temperature limitations necessary in curing concrete in hot weather?

Question: Is the slump test of value as a measure of consistency or workability?

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: What irregularities are to be avoided in the test specimen?

Question: Is the cutting of cores or other shaped specimens directly from a completed structure ever used ...

Question: What are the ultrasonic pulse velocity and the pulse echo tests?

Question: What other uses are there for the pulse velocity?

Question: What is architectural concrete?

Question: How much does a bag of cement weigh?

Question: Substantial structural damage

Question: Vapor barriers

Question: Curing Test Specimen at High Temperatures

Question: Definition of shallow and deep foundations

Question: Temperature limits for mass concrete

Question: Cleaning slabs during tilt-up construction

Question: Are stiffness modifiers mandatory in the ACI 318 Code?

Question: What is fiber-reinforced concrete?

Question: Are all fibers used in concrete the same?

Question: Will the use of fibers impact the air content of the concrete?

Question: Do fibers react when added to concrete mix?

Question: Using and handling pozzolans

Question: Aggregate classification by density

Question: The effect of aggregate characteristics on concrete shrinkage and permeability

Question: How do the code requirements get to the contractor?

Question: The effect of water-cementitious ratio on permeability and shrinkage

Question: If the paste is ample in amount, but is too thin and watery to float the aggregate particles, wh...

Question: When water and aggregate are heated, are any limitations necessary?

Question: Can the strength gain of concrete that has ceased due to drying out at early ages be restored by...

Question: How can the surface or free water carried by the aggregates be determined?

Question: How is the slump test made?

Question: What test is available to evaluate the behavior of no-slump concrete as it is vibrated?

Question: How is the temperature of concrete measured?

Question: Does the method of molding test specimens affect the test results?

Question: Why is a spherically seated bearing block required in testing cylinders?

Question: How is the air content of hardened concrete determined?

Question: How is the resistance to freezing and thawing determined?

Question: How is the permeability of concrete determined?

Question: How is the resistance to sulfate determined?

Question: How is the resistance to alkali-aggregate reaction (AAR) determined?

Question: How is the abrasion resistance of concrete determined?

Question: How is the shrinkage of concrete determined?

Question: Minimum thickness of bearing walls

Question: Painting the floor

Question: Punching shear check for shear wall foundations

Question: Decorative concrete finishes

Question: The intent of the 0.8 factor in Section 17.7.1.2.1 of ACI 318-19

Question: Addition of lime in curing tanks

Question: Temperature Control Time

Question: Water Curing Mass Concrete Structures

Question: Design of Slabs-on-ground

Question: Shear reinforcement for beam-column connections

Question: Material Requirements for Mass Concrete

Question: Minimum Dimension of a Structure