CM 2050 - Chapters 4, 5, 6 - Water/Aggregates/Admixtures

Water fit for human consumption

Potable Water

Potential blending of multiple water sources

Combined water

Process (wash) water or storm water collected; also referred to as recycled water.

Concrete production water

Water from wells, streams, or lakes that might have objectionable taste or smell

Non-Potable water

True or false; Water needs to be suitable quality for use in concrete to not adversely impact the potential properties of concrete.

True

According to the ASTM C1602: Standard Specification for Mixing Water Used in the production of Hydraulic Cement Concrete, which of the following water sources can be used in concrete without any testing or qualification?

Potable water

If water utilized for concrete is suspect (as per quality and content) what is recommended? 

Have the water tested to make an educated decision.

Water from remote sites, wells, ponds, rivers, other project sites.

Site-Sourced Water

Water reclaimed and used from the production of concrete, returned fresh concrete, reclaimed aggregates, and etc.

Recycled Water

Water supplied (possibly processed and/or treated) to meet drinking water standards. Water out of the tap.

Municipal Water Supply

Treated wastewater, used for non-potable applications

Municipal Reclaimed Water

Aggregates for use in concrete are classified into three categories. What is approximate bulk density range of Lightweight aggregate?

35 lbs/ft³ to 70 lbs/ft³ 

Aggregates for use in concrete are classified into three categories. What is the approximate bulk density range of Normal-Weight aggregate?

75 lbs/ft^3 to 110 lb/ft^3

Aggregates for use in concrete are classified into three categories. What is the approximate bulk density range of Heavyweight aggregate?

Typically over 130 lb/ft^3

Material produced by crushing sound parent rock at stone crushing plants are defined as

Manufactured aggregate

materials that can be readily used in concrete with minimal processing are defined as

Natural aggregate

True or false; grading is the particle-size distribution of an aggregate as determined by a sieve analysis.

True

Maximum size aggregate is defined as the aggregate size in which the smallest sieve size through which the major portion of the aggregate must pass (typically 85% to 95% passing through)

False; maximum size must pass 100%

True or false; Normal maximum size is defined as an aggregate is the smallest sieve that all of the particular aggregate must pass through (100% passing)

False; majority of aggregates will pass through

Material containing an excess of moisture on the surface (free water) is defined as….

Damp or Wet

Material neither absorbing water from nor contributing water to concrete mixture, equal to potential absorption is defined as….

Saturated Surface Dry (SSD)

Material that is dry at the particle surface but containing some interior moisture, less that potential absorption is defined as…

Air dry

Material containing zero moisture content being fully absorbent is defined as…..

Ovendry

Speeds the rate of hydration, shortens normal setting time.

Set Accelerator

Admixture whose properties permit a reduction of water required to produce a concrete mix of a certain slump, reduce water-cement ratio, reduce cement content, or increase slump.

Water-Reducer

Ingredients in concrete (other than hydraulic cement, SCMs, water, aggregate, fiber reinforcement) used to the mixture immediately before or during mixing. 

Chemical Admixture

Delays the setting and hardening of concrete

Set Retarder

Incorporated into the mixture in the form of minute bubbles during mixing, usually increases the material’s workability and frost resistance.

Air-Entraining

The major reason for using chemical admixtures in concrete mixtures is to________

All of the above

True or false; when cement-admixtures (cement to admixtures) or admixture-admixture (admixture to admixture) is not compatible fresh concrete problems of varying degrees of severity are encountered that affect the plastic-state performance of concrete but never affect the long term hardened concrete performance.

False; affect the long term hardened performance of concrete.

Which description best fits the term description for admixture?

Ingredients which are added to in cement before or after concrete mix

Which of the following statements is incorrect about the function of admixtures.

To retard the initial set, to keep concrete workable for a shorter time for placement.

Which of the following statements is incorrect about the function of admixtures

To increase the capillary flow of water through concrete and to increase its impermeability to liquids.

The most common, and perhaps arguably the most useful, chemical admixture for concrete exposed to outdoor elements in our region is

Entrained air

Super plasticizers ________ water requirements in the concrete mix.

Reduce

All of the following options are chemical admixtures, EXCEPT

Pozzolanic

Admixtures which cause early setting, and hardening of concrete are called ________.

Accelerators

The dosage (amount of) air-entrainment added to a concrete mix depends on all the following, EXCEPT:

All the above are factors in the dosage of air-entrainment utilized

A major function of set retarders is

Slows curing Rate