Hot Mix Asphalt (HMA)
Volumetric Properties
HMA Volumetric Terms
Bulk specific gravity (BSG) of compacted
HMA
 Maximum specific gravity
 Air voids
 Effective specific gravity of aggregate
 Voids in mineral aggregate, VMA
 Voids filled with asphalt, VFA

Volumetric Relationships
Va
VMA
Vb V
ba
Vmb
Vse Vmm
Vsb
BSG of Compacted HMA

AC mixed with agg. and compacted
into sample
Mass agg. and AC
Gmb =
Vol. agg., AC, air voids
Testing
Mixing of asphalt and aggregate
 Compaction of sample
 Mass of dry sample
 Mass under water
 Mass saturated surface dry (SSD)

Testing
Obtain mass of dry
compacted sample
Testing
Obtain mass of
specimen at SSD
Calculations

Gmb = A / ( B - C )
Where:
A = mass of dry sample
B = mass of SSD sample
C = mass of sample under water
Maximum Specific Gravity

Loose (uncompacted) mixture
Mass agg. and AC
Gmm =
Vol. agg. and AC
Testing
Mixing of asphalt and aggregate
 Mass in air
 Mass under water

Testing
Loose Mix at
Room
Temperature
Testing
Residual
Manometer
Metal Bowl with Lid
Vacuum Pump
Shaker Table
Calculations

Gmm = A / ( A - C )
Where:
A = mass of dry sample
C = mass of sample under water
Percent Air Voids

Calculated using both specific gravities
Air voids = ( 1 -
Gmb
Gmm
Mass agg + AC
Vol. agg, AC, Air Voids
Mass agg + AC
Vol. agg, AC
) 100
Vol. agg, AC
=
Vol. agg, AC, Air Voids
Example Calculations

Air voids:
– Gmb = 2.222
– Gmm = 2.423
( 1 - 2.222 / 2.423 ) 100 = 8.3 %
Effective Specific Gravity
Surface Voids
Gse =
Solid Agg.
Particle
Mass, dry
Effective Volume
Vol. of water-perm. voids
not filled with asphalt
Absorbed asphalt
Effective volume = volume of solid aggregate particle +
volume of surface voids not filled with asphalt
Effective Specific Gravity
Gse =
100 - Pb
100 - Pb
Gmm
Gb
Gse is an aggregate property
Example Calculations
Mixed with 5 % asphalt cement
 Gmm = 2.535
 Gb = 1.03

Gse =
100 - 5
= 2. 770
100 - 5
2.535 1.03
Voids in Mineral Aggregate
VMA = 100 -
Gmb Ps
Gsb
VMA is an indication of film thickness on
the surface of the aggregate
Example Calculations

Given that Gmb = 2.455, Ps = 95%, and
Gsb = 2.703
VMA = 100 -
(2.455) (95)
2.703
= 13.7
Voids Filled with Asphalt
VFA = 100 x VMA - Va
VMA
VFA is the percent of VMA that
is filled with asphalt cement
Mass Relationships
Ma = 0
Mb = Pb MT
Ms = Ps
MT
MT = Mb + Ms
Percent Binder Absorbed
G
G
se
sb
Pba = 100 (
Gsb Gse
) Gb
Pba is the percent of absorbed
asphalt by mass of aggregate
Effective Asphalt Content
Pba
Pbe =
Pb -
Ps
100
The effective asphalt content is the
total asphalt content minus the
percent lost to absorption
(based on mass of total mix).
Hot Mix Asphalt (HMA)
Volumetric Properties
Using
Phase Diagrams
VOL (cm3 )
Gmb = 2.329
air
asphalt
Gb = 1.015
Pb = 5% by mix
absorbed asph
1.000
aggregate
Gsb = 2.705
Gse = 2.731
MASS (g)
VOL (cm3 )
Gmb = 2.329
air
MASS (g)
Ma = 0
asphalt
Gb = 1.015
Pb = 5% by mix
absorbed asph
Mm = 1.0 x 2.329 x 1.0 = 2.329
1.000
aggregate
Gsb = 2.705
Gse = 2.731
M = V x G x 1.000
VOL (cm3 )
Gmb = 2.329
air
asphalt
Gb = 1.015
Pb = 5% by mix
MASS (g)
0
Mb = 0.05 x 2.329 = 0.116
absorbed asph
2.329
1.000
aggregate
Gsb = 2.705
Gse = 2.731
Ms = 2.329 - 0.116 = 2.213
VOL (cm3 )
MASS (g)
0
air
asphalt
Gb = 1.015
0.116
absorbed asph
2.329
1.000
aggregate
Gsb = 2.705
Gse = 2.731
0.818
0.810
Vse =
Vsb = 2.213
2.705x 1.0
2.213
= 0.810
2.731x 1.0
= 0.818
2.213
M
V=
G x 1.000
VOL (cm3 )
MASS (g)
0
air
asphalt
Gb = 1.015
0.114
0.008
0.116
absorbed asph
2.329
1.000
0.818
Vb =
0.810
aggregate
Gsb = 2.705
Gse = 2.731
0.116
= 0.114
1.015 x 1.0
Vba = 0.818 - 0.810 = 0.008
2.213
M
V=
G x 1.000
VOL (cm3 )
0.114
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.008
0
0.116
absorbed asph
2.329
1.000
0.818
0.810
aggregate
Gsb = 2.705
Gse = 2.731
Vbe = 0.114 - 0.008 = 0.106
Va = 1.000 - 0.114 - 0.810 = 0.076
2.213
VOL (cm3 )
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.114
0.008
absorbed asph
0
0.108
0.008
2.329
1.000
0.818
0.116
0.810
aggregate
Gsb = 2.705
Gse = 2.731
M = V x G x 1.000
2.213
Mbe = 0.106 x 1.015 x 1.000 = 0.108
Mba = 0.116 - 0.108 = 0.008
VOL (cm3 )
0.182
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.114
0.008
absorbed asph
0
0.108
0.008
2.329
1.000
0.818
0.116
0.810
aggregate
Gsb = 2.705
Gse = 2.731
2.213
Air Voids = 0.076 x 100 = 7.6 %
VMA = Vbe + Va = ( 0.106 + 0.076 ) x 100 = 18.2 %
VOL (cm3 )
0.182
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.114
0.008
absorbed asph
0
0.108
0.116
0.008
2.329
1.000
0.818
0.810
aggregate
Gsb = 2.705
Gse = 2.731
Air Voids = 7.6 %
VMA = 18.2 %
VFA = ( 0.106 / 0.182 ) x 100 = 58.2 %
2.213
VOL (cm3 )
0.182
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.114
0.008
absorbed asph
0
0.108
0.008
2.329
1.000
0.818
0.116
0.810
Air Voids = 7.6 %
VMA = 18.2 %
VFA = 58.2 %
aggregate
Gsb = 2.705
Gse = 2.731
2.213
Eff. Asp. Cont. = ( 0.108 / 2.329 ) x 100 = 4.6 %
VOL (cm3 )
0.182
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.114
0.008
absorbed asph
0
0.108
0.008
2.329
1.000
0.818
0.116
0.810
Air Voids = 7.6%
VMA = 18.2 %
VFA = 58.2 %
aggregate
Gsb = 2.705
Gse = 2.731
2.213
Effective Asphalt Content = 4.6%
Abs. Asph. Cont. = ( 0.008 / 2.213 ) x 100 = 0.4%
VOL (cm3 )
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.182
0.114
0.008
absorbed asph
0
0.108
0.008
2.329
1.000
0.818
0.116
0.810
Air Voids = 7.6%
VMA = 18.2 %
VFA = 58.2 %
aggregate
Gsb = 2.705
Gse = 2.731
2.213
Max Theo Sp Grav = 2.329
1.000 - 0.076
1.000
= 2.521
VOL (cm3 )
0.182
MASS (g)
0.076
air
0.106
asphalt
Gb = 1.015
0.114
0.008
absorbed asph
0
0.108
0.116
0.008
2.329
1.000
0.818
0.810
Air Voids = 7.6%
VMA = 18.2 %
VFA = 58.2 %
aggregate
Gsb = 2.705
Gse = 2.731
2.213
Effective Asphalt Content = 4.6%
Absorbed Asphalt Content = 0.4%
Max Theo Sp Grav = 2.521
Questions - ?