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Relative Density and Absorption

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Page 1: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Relative Density and Absorption

Page 2: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

CIVL 3137 76

Aggregate Moisture

Dry SSD Wet

Page 3: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Absorption

AW

D

M% Abs 100%M

MD

MAW

Page 4: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Question

A 1-ft3 bucket holds 100 lb. of aggregate. How much volume is occupied by the air and how much by the aggregate particles?

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Page 5: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Particle Density

Particle density is the ratio of the massof an aggregate particle to its own volume(also called mass density of solids).

MV

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Page 6: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Relative Density

Relative density is the mass densityof an object relative to the mass densityof water (also called specific gravity).

w

RD w

M V

w

MV

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Page 7: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Relative Density

Relative density depends on the volumeyou assume for the aggregate particles.

NetVolume

BulkVolume

Page 8: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Apparent Relative Density

D

NA

w

MR

VD

Net volume

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Page 9: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Bulk Relative Density

D

BB

w

MR

VD

Bulk volume

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Page 10: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

SSD Relative Density

SSD

BSSD

wVM

RD

SSD aggregate

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Page 11: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Example

An aggregate sample has an oven-dry mass of3954.2 g, an SSD mass of 4006.8 g, and a netvolume of 1532.6 cm3.

Find RDA, RDB, RDSSD, and %Abs

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Page 12: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Measuring Relative Density

CIVL 3137 86

Page 13: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Measuring Relative Density

CIVL 3137 87

Page 14: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Measuring Relative Density

w

MRD

Vmass of water displaced

CIVL 3137 88

Page 15: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Measuring Relative Density

aggregate

water displaced

MRD

M

Page 16: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Buoyancy

Mwater displaced × g

Min water × g

=Min air × g

Page 17: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Measuring Relative Density

water displaced in air in waterM M M

Page 18: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Apparent Relative Density

in air

Ain

OD

ODair in water

MRD

M M

Net volume

Page 19: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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Bulk Relative Density

in air

Bin aSSD

OD

ir in water

MRD

M M

Bulk volume

Page 20: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

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SSD Relative Density

in air

SSDi

SSD

SSDn air in water

MRD

M M

Bulk volume

Page 21: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Achieving an SSD State

Coarse aggregate should be soaked in room temperature water for 24±4 h then rolled in a large absorbent cloth to remove all visible surface moisture.

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Page 22: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Achieving an SSD State

Fine aggregate should be brought to a moisture content of at least 6% and allowed to stand for 24±4 h. Aggregate is then spread out on a nonabsorbent surface and air is blown across it until it attains a free flowing condition.

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Page 23: Relative Density and Absorption - Memphis - Civil Engineering Handouts/3 - Relative Density... · Relative Density Relative density is the mass density of an object relative to the

Achieving an SSD State

CIVL 3137 97