Course Aggregate

When discussing sieve sizes using "numbers" (i.e. "No. 8 sieve") , the number represents:

• Size of the opening in mm

• Size of the opening in inches

• The number of openings per inch

• Divide by 4, and that is the size of the opening in inches

Answer explanation

Course aggregate must be retained on sieve:

• #2

• #4

• #6

• #8

Fine aggregate must be retained on sieve:

• #400

• #200

• #50

• #30

Answer explanation

The "nominal maximum size" of an aggregate is:

• The largest sieve that retains any aggregate, but generally not more than 10%

• The smallest sieve through which 100% of the aggregate passes

• The largest dimension of the largest piece of aggregate in a sample

• The average size a piece of aggregate multiplied by 2.5

Answer explanation

Nominal Maximum vs. Maximum Aggregate Size

Maximum: Smallest sieve size through which 100% passes

Nominal Maximum: Largest sieve that retains any aggregate, but generally no more than 10%

Which picture represents aggregate that is air dry:

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Which picture represents aggregate that is saturated surface dry:

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Answer explanation

Tags

NGSS.MS-PS1-2

Bulk density is:

• Mass per unit volume, NOT including the voids

• Mass per unit volume, including the voids

• Mass divided by the mass of an equal volume of water, NOT including voids

• Mass divided by the mass of an equal volume of water, including voids

Answer explanation

Definition from ASTM C29

Specific gravity is:

• Mass per unit volume, NOT including the voids

• Mass per unit volume, including the voids

• Mass divided by the mass of an equal volume of water, NOT including voids

• Mass divided by the mass of an equal volume of water, including voids

Answer explanation

This definition is located ASTM C125: Terminology Related to Concrete and Concrete Aggregate. ASTM C127 does not contain any information in the terminology section, it references ASTM C125.

When performing ASTM C29 to calculate the bulk density of an aggregate, we will calibrate the volume of the measure ("metal bucket") by using:

• Water

• Sand

• Air

• Tape Measure

Answer explanation

When calibrating the measure with water, the temperature of the water maters because:

• Thermal deformation will change the volume of the measure

• Water's density changes as a function of temperature

• The meniscus of the water will increase as temperature increases

Answer explanation

Tags

NGSS.MS-PS1-4