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

Asphalt Mix Volumetrics

Mix Volumetrics Aggregate Particle Bulk Volume (V G ) (M G ,V G ) Water Permeable Voids CIVL 3137 2

Mix Volumetrics Absorbed Aggregate Asphalt Particle (M BA ,V BA ) (M G ,V G ) Water Absorbed asphalt Permeable is wasted asphalt Voids CIVL 3137 3

Mix Volumetrics Effective asphalt Aggregate is what binds the Particle aggregate particles (M G ,V G ) together Effective Water Asphalt Permeable (M BE ,V BE ) Voids CIVL 3137 4

Mix Volumetrics Absorbed Aggregate Asphalt Particle (M BA ,V BA ) (M G ,V G ) Effective Water Asphalt Permeable (M BE ,V BE ) Voids CIVL 3137 5

Masses M G = mass of aggregate M BE = mass of effective binder (asphalt) M BA = mass of absorbed binder (asphalt) M B = total mass of binder = M BE + M BA M = total mass of mix = M G + M B CIVL 3137 7

Mass Ratios P BE = effective binder content = M BE / M P BA = absorbed binder content = M BA / M P B = binder content = M B / M CIVL 3137 8

Volumes V G = bulk volume of aggregate V BE = volume of effective binder (asphalt) V BA = volume of absorbed binder (asphalt) V B = total volume of binder = V BE + V BA V GE = effective volume of aggregate = V G ‒ V BA CIVL 3137 9

Bulk Volume Aggregate Particle Water Permeable Voids CIVL 3137 10

Net Volume Aggregate Particle Water Permeable Voids CIVL 3137 11

Effective Volume Absorbed Aggregate Asphalt Particle Water Permeable Voids CIVL 3137 12

More Volumes V A = volume of air voids in compacted mix V MM = volume of voidless mix = V G + V BE V = total volume of mix = V G + V BE + V A CIVL 3137 14

Volume of Air Voids Air Voids (V A ) CIVL 3137 15

Volume Ratios Voids in Total Mix (VTM) = V A /V Voids in Mineral Aggregate (VMA) = (V A + V BE )/V Voids Filled with Asphalt (VFA) = V BE /(V BE + V A ) CIVL 3137 16

Voids in Total Mix (VTM)    V      A mb VTM 100% 1 100%    V   mm  mb = bulk density of compacted mixture D 2726 - Bulk Specific Gravity and Density of Compacted Bituminous Mixtures  mm = maximum density of the mixture D 2041 - Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures CIVL 3137 17

Voids in Total Mix (VTM)   V G      A mb VTM 100% 1 100%   V G   mm G mb = bulk specific gravity of compacted mixture D 2726 - Bulk Specific Gravity and Density of Compacted Bituminous Mixtures G mm = maximum specific gravity of the mixture D 2041 - Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures CIVL 3137 18

ASTM D 2726 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. M asphalt in air  G mb  M M in air in water CIVL 3137 19

ASTM D 2041 “Rice” Test 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 CIVL 3137 20

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 of the mix is 2.35, what is the air void content (voids in total mix) of the specimen? CIVL 3137 21

Voids in Mineral Aggregate VTM VMA (Voids in Total Mix) (Voids in Mineral Aggregate) CIVL 3137 22

Voids in Mineral Aggregate        1 P V V      mb b BE A VMA 100% 1 100%    V   sb  mb = bulk density of compacted mixture  sb = bulk density of the aggregate blend P b = asphalt binder content of mixture CIVL 3137 23

Voids in Mineral Aggregate       G 1 P V V      mb b BE A VMA 100% 1 100%   V G   sb G mb = bulk relative density of compacted mixture G sb = bulk relative density of the aggregate blend P b = asphalt binder content (to the nearest 0.1%) CIVL 3137 24

Bulk Density of Aggregate Blend    G sb sb w 1 f f f     1 2 n  G G G G sb 1 2 n G i = bulk relative density of aggregate i f i = fraction of blend from aggregate i CIVL 3137 25

Example The compacted asphalt concrete specimen from the previous example has a 6% asphalt content. If the aggregate blend contains 40% screenings (G s = 2.65), 40% sand (G s = 2.69) and 20% gravel (G s = 2.61), what is the VMA of the specimen? CIVL 3137 26

Voids Filled with Asphalt   V VTM      VFA BE 100% 1 100%    V V  VMA  BE A 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. CIVL 3137 27

Example What is the VFA of the compacted specimen from the previous examples? CIVL 3137 28

Aggregate Specifications

Right Type of Aggregate Dense-graded Hard Durable Rough-surfaced Cubical (angular and equidimensional) Hydrophobic Free from deleterious substances Low Porosity CIVL 3137 30

TDOT Specifications CIVL 3137 31 Source: Standard Specifications for Road and Bridge Construction (TDOT, 2006)

TDOT Specifications Asphalt Coarse Aggregate LA Abrasion Loss < 40% (Hard) Absorption < 5% (Low Porosity) 2+ Fractures Faces > 70% (Angular) 5:1 Elongated < 20% (Equidimensional) Sodium Soundness Loss < 9% (Durable) CIVL 3137 32

TDOT Specifications Asphalt Fine Aggregate Material Passing No. 200 Sieve < 4% (Free of deleterious substances) Clay Lumps < 0.5% (Free of deleterious substances) Coal and Lignite < 0.5% (Free of deleterious substances) Other Deleterious Substances < 3% (Free of deleterious substances) Sodium Soundness Loss < 12% (Durable) CIVL 3137 33

TDOT Specifications CIVL 3137 34

TDOT Specifications 1½" ¾" 3 / 8 " 4 8 16 30 50 100 200 100 80 TDOT Percent Passing Grading D 60 40 Maximum Density Curve 20 0 100 10 1 0.1 0.01 Opening Size (mm) CIVL 3137 35

TDOT Specifications 1½" ¾" 3 / 8 " 4 8 16 30 50 100 200 100 80 TDOT Percent Passing Grading E 60 40 Maximum Density Curve 20 0 100 10 1 0.1 0.01 Opening Size (mm) CIVL 3137 36

TDOT Specifications 1½" ¾" 3 / 8 " 4 8 16 30 50 100 200 100 80 TDOT Percent Passing Grading F 60 40 20 0 100 10 1 0.1 0.01 Opening Size (mm) CIVL 3137 37

Superpave Specifications Source: NCEES FE Supplied Reference Handbook CIVL 3137 38

19-mm Gradation Example 100 Percent Passing (%) 80 60 40 20 0 0 1 2 3 4 5 Opening Size (mm) Raised to the 0.45 Power CIVL 3137 40

Superpave Specifications Source: NCEES FE Supplied Reference Handbook CIVL 3137 41

Flexible Pavements Stress decreases with depth CIVL 3137 42

Superpave Specifications COARSE AGGREGA TE ANGULARITY Source: NCEES FE Supplied Reference Handbook CIVL 3137 43

Coarse Aggregate Angularity Fractured Face Fractured Faces Fractured Faces CIVL 3137 44 Source: http://pavementinteractive.org

Superpave Specifications FINE AGGREGA TE ANGULARITY Source: NCEES FE Supplied Reference Handbook CIVL 3137 45

Fine Aggregate Angularity m V  sand sand RD   sand w V  V  V voids cyl sand V % Voids   100% voids V cyl Source: http://pavementinteractive.org CIVL 3137 46

Superpave Specifications FLA T AND ELONGA TED PARTICLES Source: NCEES FE Supplied Reference Handbook CIVL 3137 47

Particle Shape (Flat and Elongated Particles) CIVL 3137 48 Source: http://pavementinteractive.org

Superpave Specifications CLA Y CONTENT Source: NCEES FE Supplied Reference Handbook CIVL 3137 49

Clay Content (Sand Equivalent Test) H SE   100% sand H clay H clay H sand Source: http://pavementinteractive.org