volumetric analysis of hma mixtures - rowan...
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1Volumetric Analysis of HMA Mixtures
VOLUMETRIC ANALYSIS OF HMA
MIXTURES
2Volumetric Analysis of HMA Mixtures
Volumetrics
• All matter has mass and occupies space
• Volumetrics are the relationships between mass and volume
3Volumetric Analysis of HMA Mixtures
Specific Gravity, G
MassVolume * w
4Volumetric Analysis of HMA Mixtures
Basic Terms• Specific Gravity (G): Gxy
– x: b = binders = stone (i.e., aggregate)m = mixture
– y: b = bulke = effectivea = apparentm = maximum
– Example:• Gmm = gravity, mixture, maximum(i.e., maximum gravity of the mixture)
5Volumetric Analysis of HMA Mixtures
Basic Terms (cont.)• Mass (P) or Volume (V) Concentration: Pxy or Vxy
– x: b = binders = stone (i.e., aggregate)a = air
– y: e = effectivea = absorbed
– Example:• Pb = percent binder
6Volumetric Analysis of HMA Mixtures
Volumetric Relationships
Vmb Vsb
VbaVb
Vse Vmm
Va VMA
7Volumetric Analysis of HMA Mixtures
HMA Volumetric Terms• Bulk specific gravity (Gmb) of compacted
HMA• Maximum specific gravity (Gmm)• Air voids or voids total mix (Va)• Effective specific gravity of aggregate (Gse)• Voids in mineral aggregate, VMA• Voids filled with asphalt, VFA
8Volumetric Analysis of HMA Mixtures
Gmb of Compacted HMA• AC mixed with agg. and compacted into
sampleMass agg. and AC
Vol. agg., AC, air voidsGmb =
Vmb
9Volumetric Analysis of HMA Mixtures
Testing
• Mixing of asphalt and aggregate• Compaction of sample• Mass of dry sample• Mass under water• Mass saturated surface dry (SSD)
10Volumetric Analysis of HMA Mixtures
TestingObtain mass
of dry compacted
sample
11Volumetric Analysis of HMA Mixtures
Soak in water for 3 Soak in water for 3 –– 5 minutes5 minutes
12Volumetric Analysis of HMA Mixtures
Testing
Obtain mass of specimen at SSD
13Volumetric Analysis of HMA Mixtures
Calculations• Gmb = A / ( B - C )
Where:A = mass of dry sampleB = mass of SSD sampleC = mass of sample under water
14Volumetric Analysis of HMA Mixtures
Maximum Specific Gravity
Loose (uncompacted) mixtureMass agg. and AC
Vol. agg. and ACGmm =
Vmm
15Volumetric Analysis of HMA Mixtures
Testing
• Mixing of asphalt and aggregate• Mass in air• Mass under water
16Volumetric Analysis of HMA Mixtures
TestingLoose Mix at
Room Temperature
17Volumetric Analysis of HMA Mixtures
Testing
Vacuum Pump
Residual Manometer
Metal Bowl with Lid
Shaker Table
18Volumetric Analysis of HMA Mixtures
Calculations• Gmm = A / ( A - C )
Where:A = mass of dry sampleC = mass of sample under water
19Volumetric Analysis of HMA Mixtures
Air VoidsCalculated using bulk and maximum
specific gravities
Air voids (Va) = 100 * Gmm – Gmb
Gmm
Vmb
Va
20Volumetric Analysis of HMA Mixtures
Why Are Air Voids Important?
• Related to Rut Resistance• Related to Durability (aging and fatigue)
21Volumetric Analysis of HMA Mixtures
Effective volume = volume of solid aggregate particle + volume of surface voids not filled with asphalt
Gse = Mass, dry
Effective Specific Gravity
Effective Volume
Absorbed asphalt
Vol. of water-perm. voidsnot filled with asphalt
Surface Voids
Solid Agg.Particle
22Volumetric Analysis of HMA Mixtures
Effective Specific Gravity
Gse is an aggregate propertyDetermined from a mix test
Gse = 100 - Pb
100 - Pb
Gmm Gb
23Volumetric Analysis of HMA Mixtures
Voids in Mineral Aggregate
VMA is an indication of film thickness on the surface of the aggregate
VMA = 100 - Gmb Ps
Gsb
Vmb
VMA
24Volumetric Analysis of HMA Mixtures
Voids Filled with Asphalt
VFA is the percent of VMA that is filled with asphalt cement
VFA = 100 x VMA - Va
VMA
25Volumetric Analysis of HMA Mixtures
Percent Binder Absorbed
Pba is the percent of absorbed asphalt by wt. of aggregate
Pba = 100 ( Gse - Gsb
Gse Gsb) Gb
26Volumetric Analysis of HMA Mixtures
Effective Asphalt Content
The effective asphalt content is the total asphalt content minus the
percent lost to absorption?
Pbe = Pb -Pba
100Ps
27Volumetric Analysis of HMA Mixtures
Dust /Asphalt Ratio
F % passing No. 200F % passing No. 200==AA % % PPbebe
28Volumetric Analysis of HMA Mixtures
Factors That Influence Volumetric of HMA
• Asphalt viscosity• Mix temperature• Time held at elevated temperature
29Volumetric Analysis of HMA Mixtures
Important Considerations
• Consistent laboratory procedures– Equiviscous mixing temperatures – Mixing times
• Curing time to simulate field conditions
30Volumetric Analysis of HMA Mixtures
Example Problem
31Volumetric Analysis of HMA Mixtures
- Example Problem -• Let’s assume we have a compacted HMA
mixture with the following properties.
Bulk Specific Gravity of the Mixture - Gmb = 2.425Theoretical Maximum Specific Gravity - Gmm = 2.521Asphalt Binder Specific Gravity - Gb = 1.015Asphalt Content - Pb = 5.0 % (by mass of total mix)Percent passing No. 200 = 5.3%
32Volumetric Analysis of HMA Mixtures
- Example Problem -• Let’s also assume that three stockpiled
aggregates were used to manufacture this HMA mixture. The percent of each aggregate and the Bulk Specific Gravity (Gsb) for each is as follows:
Aggregate % of Total Aggregate G sb2.6952.7112.721
ABC
50 %25 %25 %
-Example Problem –• Based on the information given for this problem, the
following steps should be followed:– Calculate the bulk specific gravity of the combined
aggregate– Calculate the effective specific gravity of the aggregate– Calculate the percent absorbed asphalt for the mixture– Calculate the percent effective asphalt for the mixture– Calculate the percent voids in total mix for the mixture– Calculate the percent voids in mineral aggregate for the
mixture– Calculate the percent voids filled with asphalt for the
mixture– Calculate the dust to asphalt ratio
-Example Problem –• Bulk Specific Gravity of the Combined
Aggregate - Gsb
GA GB GC
( PA + PB + PC ) PA PB PC
= 2.705
Where: PA, PB & PC = Percent by Mass of Each Aggregate in Blend GA,
GB & GC = Bulk Specific Gravity of Each Aggregate
Based on the information given:
GA = 2.695GB = 2.711GC = 2.721
PA = 50%PB = 25%PC = 25%
Gsb =
2.695 2.711 2.721
( 50+ 25 + 25 ) 50 25 25 Gsb =
++ ++
++++
35Volumetric Analysis of HMA Mixtures
• Effective Specific Gravity of Aggregate - Gse
Gmm Gb
100 - Pb
100 Pb
= 2.735
Where: Pb = Percent Asphalt Binder by Total Mass of Mixture
Gmm = Theoretical Maximum SpecificGravity of Mixture
Gb = Specific Gravity of Asphalt Binder
Pb = 5.0 %Gmm = 2.521Gb = 1.015
Gse =
2.521 1.015
100- 5.0100 5.0Gse =
--
--
-Example Problem –
Based on the information given:
36Volumetric Analysis of HMA Mixtures
• Percent Absorbed Asphalt Binder - Pba
(100 * Gb) (Gse - Gsb)Gse * Gsb
= 0.4 %
Where: Gb = Specific Gravity of Asphalt Binder Gse = Effective Specific Gravity of
AggregateGsb = Bulk Specific Gravity of Aggregate
Gb = 1.015Gse = 2.735Gsb = 2.705
Pba =
( 100 * 1.015 ) (2.735 - 2.705 )( 2.735 * 2.705 )Pba =
-Example Problem –
Based on the information given:
37Volumetric Analysis of HMA Mixtures
• Percent Effective Asphalt Binder - Pbe
( Pba * Ps )100
Where: Pb = Percent Asphalt Binder in Total MixPba = Percent Absorbed Asphalt Binder
in Total MixPs = Percent Aggregate in Total Mix
Pb = 5.0 %Pba = 0.4 %Ps = 95.0 %
Pb -
= 4.6 %
Pbe =
( 0.4 * 95.0 )1005.0 -Pbe =
-Example Problem –
Based on the information given:
38Volumetric Analysis of HMA Mixtures
• Percent Voids in Total Mix - Va
( Gmm - Gmb )Gmm
Where: Gmm = Theoretical MaximumSpecific Gravity of Mix
Gmb = Bulk Specific Gravity of Mix
Gmm = 2.521Gmb = 2.329
= 3. 8 %
Va, % = 100 *
(2.521 - 2.425 )
2.521Va = 100 *
-Example Problem –
Based on the information given:
39Volumetric Analysis of HMA Mixtures
• Percent Voids in Mineral Aggregate - VMA
( Gmb * Ps )Gsb
Where: Gmb = Bulk Specific Gravity of MixPs = Percent Aggregate in Total
MixGsb = Bulk Specific Gravity of
Aggregate
Gmb = 2.329Ps = 95.0 %Gsb = 2.705
= 14.8
VMA, % = 100 -
( 2.425 * 95.0 )2.705
VMA = 100 -
-Example Problem –
Based on the information given:
40Volumetric Analysis of HMA Mixtures
• Percent Voids Filled with Asphalt - VFA
( VMA - Va)VMA
Where: VMA = percent Voids in Mineral Aggregate
Va = percent Voids in Total Mix
VMA = 14.8 %Va = 3.8 %
= 74 %
VFA, % = 100 *
( 14.8 - 3.8 )14.8
VFA = 100 *
-Example Problem –
Based on the information given:
41Volumetric Analysis of HMA Mixtures
Dust /Asphalt Ratio
F % passing No. 200F % passing No. 200==AA PPbebe
Given: PGiven: P--200200 = 5.3%= 5.3%
F 5.3F 5.3A 4.60A 4.60
== = 1.15= 1.15
42Volumetric Analysis of HMA Mixtures
Example Problem -Volumetric Equations
• SummaryGsb = 2.705Gse = 2.732Pbe , % = 4.6 %Pba , % = 0.4 %Va, % = 3.8 %VMA , % = 14.8 %VFA, % = 74 %F/A = 1.15
Volumetric Analysis of HMA Mixtures 43
Classroom Exercise
44Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Let’s assume we have a compacted HMA mixture
with the following properties at 25o C.
Bulk Specific Gravity of the Mixture - Gmb = 2.413Theoretical Maximum Specific Gravity - Gmm = 2.501Asphalt Binder Specific Gravity - Gb = 1.025Asphalt Content - Pb = 4.3 % (by mass of total mix)Percent Passing No. 200 = 4.8%
45Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Let’s also assume that four stockpiled aggregates
were used to manufacture this HMA mixture. The percent of each aggregate and the Bulk Specific Gravity (Gsb) for each is as follows:
Aggregate % of Total Aggregate Gsb
2.6502.6612.6752.697
ABCD
45 %15 %25 %15 %
46Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -
• Based on the information given for this problem, the following steps should be followed:
– Calculate the Bulk Specific Gravity of the combined aggregate– Calculate the Effective Specific Gravity of the aggregate– Calculate the Percent Absorbed Asphalt for the Mixture– Calculate the Percent Effective Asphalt For the Mixture– Calculate the Percent Voids in Total Mix for the Mixture– Calculate the Percent Voids in Mineral Aggregate for the Mixture– Calculate the Percent Voids Filled with Asphalt for the Mixture– Calculate the Dust/AC Ratio
47Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Bulk Specific Gravity of the Combined Aggregate - Gsb
GA GB GC GD
( PA + PB + PC + PD ) PA PB PC PD
Where: PA , PB , PC & PD = percent by mass of eachaggregate in blend
GA , GB , GC & GD= Bulk Specific Gravity of each aggregate
Based on the information given:GA = GB = GC = GD =
PA = %PB = %PC = %PD = %
Gsb =
Gsb =
++++++
48Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Effective Specific Gravity of Aggregate - Gse
Gmm Gb
100-Pb
100 Pb
Where: Pb = percent asphalt binder by total massof mixture
Gmm = Theoretical Maximum SpecificGravity of mixture
Gb = Specific Gravity of asphalt binder
Based on the information given:Pb = %
Gmm =
Gb =
Gse =
Gse =
--
49Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Percent Absorbed Asphalt Binder - Pba
(100 * Gb) (Gse - Gsb)Gse * Gsb
Where: Gb = Specific Gravity of asphalt binder Gse = Effective Specific Gravity of aggregateGsb = Bulk Specific Gravity of aggregate
Based on the information known:Gb =
Gse =
Gsb =
Pba =
Pba =
50Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Percent Effective Asphalt Binder - Pbe
( Pba * Ps )100
Where: Pb = percent asphalt binder in total mixPba = percent Absorbed Asphalt Binder
into aggregatePs = percent aggregate in total mix
Based on the information known:
Pb = %
Pba = %
Ps = %
Pb -Pbe =
Pbe =
51Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Percent Voids in Total Mix - VTM
( Gmm - Gmb )Gmm
Where: Gmm = Theoretical Maximum SpecificGravity of mix
Gmb = Bulk Specific Gravity of mix
Based on the information known:Gmm =
Gmb =
Va, % = 100 *
Va =
52Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Percent Voids in Mineral Aggregate - VMA
( Gmb * Ps )Gse
Where: Gmb = Bulk Specific Gravity of mixPs = percent aggregate in total mixGse = Effective Specific Gravity of
aggregate
Based on the information known:Gmb =
Ps = %
Gse =
VMA, % = 100 -
VMA =
53Volumetric Analysis of HMA Mixtures
- Classroom Exercise 1 -• Percent Voids Filled with Asphalt - VFA
( VMA - Va)VMA
Where: VMA = percent Voids in Mineral Aggregate
Va = percent Voids in Total Mix
Based on the information known:VMA = %
Va = %
VFA, % = 100 *
VFA =
54Volumetric Analysis of HMA Mixtures
Dust /Asphalt Ratio
F F % passing No. 200% passing No. 200==AA PbePbe
PP--200 = 200 =
PbePbe = =
==
Based on the information known:
Α
F
55Volumetric Analysis of HMA Mixtures
- Classroom Problem 1 -• Summary
Gsb = Gse = Pba , % = Pbe , % = Va, % = VMA, % = VFA, % = F/A =
Volumetric Analysis of HMA Mixtures 56
Classroom Exercise 2
57Volumetric Analysis of HMA Mixtures
Classroom Exercise 3• Given
– Gmm = 2.474– Asphalt Content = 4.5 %– Bulk Sp. Gravity of Aggregate = 2.603– Bulk Sp. Gravity of Asphalt = 1.020
• Determine Gmm at 5.0, 5.5 & 6.0 %
58Volumetric Analysis of HMA Mixtures
Asphalt Content 4.5% 5.0% 5.5% 6.0%
Gmm
59Volumetric Analysis of HMA Mixtures
Questions –does it all
make sense?