Relative Density 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 % AbsAW 100% MD
MAW
CIVL 3137 4 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?
CIVL 3137 5 Particle Density
Particle density is the ratio of the mass 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 water (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 Buoyancy
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