[PPT] - Asphalt Mix Volumetrics Mix Volumetrics Aggregate Particle Bulk PowerPoint Presentation

SLIDE 1

Asphalt Mix Volumetrics

SLIDE 2

CIVL 3137 2

Mix Volumetrics

Aggregate Particle (MG ,VG) Water Permeable Voids Bulk Volume (VG)

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CIVL 3137 3

Mix Volumetrics

Aggregate Particle (MG ,VG) Water Permeable Voids Absorbed Asphalt (MBA ,VBA)

Absorbed asphalt is wasted asphalt

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CIVL 3137 4

Mix Volumetrics

Aggregate Particle (MG ,VG) Water Permeable Voids Effective Asphalt (MBE ,VBE)

Effective asphalt is what binds the aggregate particles together

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CIVL 3137 5

Mix Volumetrics

Aggregate Particle (MG ,VG) Water Permeable Voids Effective Asphalt (MBE ,VBE) Absorbed Asphalt (MBA ,VBA)

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CIVL 3137 7

Masses

MG = mass of aggregate MBE = mass of effective binder (asphalt) MBA = mass of absorbed binder (asphalt) MB = total mass of binder = MBE + MBA M = total mass of mix = MG + MB

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CIVL 3137 8

Mass Ratios

PBE = effective binder content = MBE / M PBA = absorbed binder content = MBA / M PB = binder content = MB / M

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CIVL 3137 9

Volumes

VG = bulk volume of aggregate VBE = volume of effective binder (asphalt) VBA = volume of absorbed binder (asphalt) VB = total volume of binder = VBE + VBA VGE = effective volume of aggregate = VG ‒ VBA

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CIVL 3137 10

Bulk Volume

Aggregate Particle Water Permeable Voids

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CIVL 3137 11

Net Volume

Aggregate Particle Water Permeable Voids

SLIDE 11

CIVL 3137 12

Effective Volume

Aggregate Particle Water Permeable Voids Absorbed Asphalt

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CIVL 3137 14

More Volumes

V

A = volume of air voids in compacted mix

VMM = volume of voidless mix = VG + VBE V = total volume of mix = VG + VBE + V

A

SLIDE 13

Volume of Air Voids

CIVL 3137 15

Air Voids (V

A)

SLIDE 14

CIVL 3137 16

Volume Ratios

Voids in Total Mix (VTM) = V

A/V

Voids in Mineral Aggregate (VMA) = (V

A + VBE)/V

Voids Filled with Asphalt (VFA) = VBE/(VBE + V

A)

SLIDE 15

CIVL 3137 17

Voids in Total Mix (VTM)

mb A mm

V VTM 100% 1 100% V             

mb = bulk density of compacted mixture

D 2726 - Bulk Specific Gravity and Density

f Compacted Bituminous Mixtures

mm = maximum density of the mixture

D 2041 - Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures

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CIVL 3137 18

Voids in Total Mix (VTM)

mb A mm

G V VTM 100% 1 100% V G           

Gmb = bulk specific gravity of compacted mixture

D 2726 - Bulk Specific Gravity and Density

f Compacted Bituminous Mixtures

Gmm = maximum specific gravity of the mixture

D 2041 - Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures

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ASTM D 2726

CIVL 3137 19

Compact the asphalt concrete to the same density as it will have in the pavement then weigh it in air and weigh it suspended in water.

asphalt in air mb in air in water

M G M M  

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ASTM D 2041 “Rice” Test

CIVL 3137 20

Disaggregate the asphalt concrete into individual asphalt coated rocks and small clusters of sand and asphalt … … then determine the bulk specific gravity of the material

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Example

A compacted asphalt concrete specimen has a mass in air of 1200 g and an apparent mass in water of 650 g. If the maximum specific gravity

f the mix is 2.35, what is the air void content

(voids in total mix) of the specimen?

CIVL 3137 21

SLIDE 20

CIVL 3137 22

Voids in Mineral Aggregate

VTM

(Voids in Total Mix)

VMA

(Voids in Mineral Aggregate)

SLIDE 21

CIVL 3137 23

Voids in Mineral Aggregate

 

mb b BE A sb

1 P V V VMA 100% 1 100% V                mb = bulk density of compacted mixture sb = bulk density of the aggregate blend Pb = asphalt binder content of mixture

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CIVL 3137 24

Voids in Mineral Aggregate

 

mb b BE A sb

G 1 P V V VMA 100% 1 100% V G              Gmb = bulk relative density of compacted mixture Gsb = bulk relative density of the aggregate blend Pb = asphalt binder content (to the nearest 0.1%)

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CIVL 3137 25

Bulk Density of Aggregate Blend

sb sb w

G    Gi = bulk relative density of aggregate i fi = fraction of blend from aggregate i

1 2 n sb 1 2 n

f f f 1 G G G G     

SLIDE 24

Example

The compacted asphalt concrete specimen from the previous example has a 6% asphalt

content. If the aggregate blend contains 40%

screenings (Gs = 2.65), 40% sand (Gs = 2.69) and 20% gravel (Gs = 2.61), what is the VMA

f the specimen?

CIVL 3137 26

SLIDE 25

CIVL 3137 27

Voids Filled with Asphalt

BE BE A

V VTM VFA 100% 1 100% V V VMA            

VFA is the percentage of the available space between the aggregate particles (the VMA) that is occupied by effective asphalt binder rather than by air voids.

SLIDE 26

Example

What is the VFA of the compacted specimen from the previous examples?

CIVL 3137 28

SLIDE 27

Aggregate Specifications

SLIDE 28

CIVL 3137 30

Right Type of Aggregate

Dense-graded Hard Durable Rough-surfaced Cubical (angular and equidimensional) Hydrophobic Free from deleterious substances Low Porosity

SLIDE 29

CIVL 3137 31

TDOT Specifications

Source: Standard Specifications for Road and Bridge Construction (TDOT, 2006)

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CIVL 3137 32

TDOT Specifications

Absorption < 5% 2+ Fractures Faces > 70% 5:1 Elongated < 20% LA Abrasion Loss < 40%

Asphalt Coarse Aggregate

Sodium Soundness Loss < 9%

(Hard) (Low Porosity) (Angular) (Equidimensional) (Durable)

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CIVL 3137 33

TDOT Specifications

Clay Lumps < 0.5% Coal and Lignite < 0.5% Other Deleterious Substances < 3% Material Passing No. 200 Sieve < 4%

Asphalt Fine Aggregate

Sodium Soundness Loss < 12%

(Free of deleterious substances) (Free of deleterious substances) (Free of deleterious substances) (Free of deleterious substances) (Durable)

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CIVL 3137 34

TDOT Specifications

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CIVL 3137 35

TDOT Specifications

20 40 60 80 100 0.01 0.1 1 10 100 Percent Passing Opening Size (mm)

1½" ¾"

3/8"

4 8 16 30 50 100 200 TDOT Grading D

Maximum Density Curve

SLIDE 34

CIVL 3137 36

TDOT Specifications

20 40 60 80 100 0.01 0.1 1 10 100 Percent Passing Opening Size (mm)

1½" ¾"

3/8"

4 8 16 30 50 100 200

Maximum Density Curve

TDOT Grading E

SLIDE 35

CIVL 3137 37

TDOT Specifications

20 40 60 80 100 0.01 0.1 1 10 100 Percent Passing Opening Size (mm)

1½" ¾"

3/8"

4 8 16 30 50 100 200 TDOT Grading F

SLIDE 36

CIVL 3137 38

Superpave Specifications

Source: NCEES FE Supplied Reference Handbook

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CIVL 3137 40

19-mm Gradation Example

20 40 60 80 100 1 2 3 4 5 Percent Passing (%) Opening Size (mm) Raised to the 0.45 Power

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CIVL 3137 41

Superpave Specifications

Source: NCEES FE Supplied Reference Handbook

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CIVL 3137 42

Flexible Pavements

Stress decreases with depth

SLIDE 40

CIVL 3137 43

Superpave Specifications

Source: NCEES FE Supplied Reference Handbook

COARSE AGGREGA TE ANGULARITY

SLIDE 41

Coarse Aggregate Angularity

Source: http://pavementinteractive.org

Fractured Face Fractured Faces Fractured Faces

CIVL 3137 44

SLIDE 42

CIVL 3137 45

Superpave Specifications

Source: NCEES FE Supplied Reference Handbook

FINE AGGREGA TE ANGULARITY

SLIDE 43

Fine Aggregate Angularity

Source: http://pavementinteractive.org

 

voids cyl

V % Voids 100% V   

sand sand sand w

m V RD  

voids cyl sand

V V V

CIVL 3137 46

SLIDE 44

CIVL 3137 47

Superpave Specifications

Source: NCEES FE Supplied Reference Handbook

FLA T AND ELONGA TED PARTICLES

SLIDE 45

Particle Shape

(Flat and Elongated Particles)

Source: http://pavementinteractive.org CIVL 3137 48

SLIDE 46

CIVL 3137 49

Superpave Specifications

Source: NCEES FE Supplied Reference Handbook

CLA Y CONTENT

SLIDE 47

Clay Content

(Sand Equivalent Test)

 

sand clay

H SE 100% H

Source: http://pavementinteractive.org

sand

H

clay

H