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Relative and Absorption Important Properties

Gradation Relative density and absorption Hardness (resistance to wear) Durability (resistance to weathering) Shape and surface texture Deleterious substances Crushing strength Soft and lightweight particles Chemical stability

CIVL 3137 2 Absorption

Dry SSD Wet

CIVL 3137 3 Absorption

MD M % AbsAW 100% MD

MAW

CIVL 3137 4 Question

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

CIVL 3137 5 Particle Density

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

Mkg g or  33 V mcm

CIVL 3137 6 Particle Density

Particle density can also be expressed as the ratio of the weight of an aggregate particle to its own volume.

Wlb  3 V ft

CIVL 3137 7 Relative Density

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

 MV M RD    w w V  w

CIVL 3137 8 Relative Density

Relative density (specific gravity)can also be expressed in weight-based units.

 WV W RD    w w V  w

CIVL 3137 9 Relative Density

Relative density depends on the volume you assume for the aggregate particles.

Net Bulk Volume Volume

CIVL 3137 10 Relative Density

It also depends on the mass you assume for the aggregate particles.

Dry SSD Mass Mass

CIVL 3137 11 Apparent Relative Density

MD RDA  VN  w

Net volume

CIVL 3137 12 Bulk (OD) Relative Density

MD RDB  VB  w

Bulk volume

CIVL 3137 13 SSD Relative Density

MSSD RDSSD  VB  w

SSD aggregate

CIVL 3137 14 Example

An aggregate sample has an oven-dry mass of 3954.2 g, an SSD mass of 4006.8 g, and a net volume of 1532.6 cm3.

Find RDA, RDB, RDSSD, and %Abs

CIVL 3137 15 Question

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

CIVL 3137 18 Question

A 1-m3 bucket holds 1500 kg of aggregate from the last example. How much volume is occupied by the air and how much by the aggregate particles?

CIVL 3137 21 Measuring Relative Density Lab 4.8-2

CIVL 3137 24 Measuring Relative Density

M RD  V  w

mass of water displaced

CIVL 3137 25 Measuring Relative Density

M RD  aggregate Mwater displaced

CIVL 3137 26

Mwater displaced × g =

Min water × g Min air × g

CIVL 3137 27 Measuring Relative Density

MMMwater displaced in air in water

CIVL 3137 28 Apparent Relative Density

OD Min air RDA  OD MMin air in water

Net volume

CIVL 3137 29 Bulk (OD) Relative Density

OD Min air RDB  SSD MMin air in water

Bulk volume

CIVL 3137 30 SSD Relative Density

SSD Min air RDSSD  SSD MMinair inwater

Bulk volume

CIVL 3137 31 Measuring Relative Density Lab 4.8-3

CIVL 3137 32 Measuring Relative Density

~ 500 g

~ 500 g ~ 500 g

Mwater Msand Mblend

CIVL 3137 33 Measuring Relative Density

MMMMwater displaced water sand blend

CIVL 3137 34 Apparent Relative Density

MOD RD  sand A OD MMMwater sand blend

Net volume

CIVL 3137 35 Bulk (OD) Relative Density

MOD RD  sand B SSD MMMwater sand blend

Bulk volume

CIVL 3137 36 SSD Relative Density

MSSD RD  sand SSD SSD MMMwater sand blend

Bulk volume

CIVL 3137 37 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.

CIVL 3137 38 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.

CIVL 3137 39 Achieving an SSD State

CIVL 3137 40 CIVL 3137 41