Asphalt Concrete Properties

Mix Volumetrics Aggregate Particle (M G,V G ) Absorbed Asphalt (M BA,V BA ) Effective Asphalt (M BE,V BE ) Water Permeable Voids CIVL 3137 2

Mix Volumetrics CIVL 3137 3

Masses and Mass Ratios 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 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 4

Bulk Volume Aggregate Particle Water Permeable Voids CIVL 3137 6

Net Volume Aggregate Particle Water Permeable Voids CIVL 3137 7

Effective Volume Aggregate Particle Absorbed Asphalt Water Permeable Voids 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 V A = volume of air voids in compacted mix V = total volume of mix = V G + V BE + V A V MM = volume of voidless mix = V G + V BE CIVL 3137 10

Volume of Air Voids Air Voids (V A ) CIVL 3137 11

Volume Ratios Air Voids (AV) = 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 12

Air Voids V A mb AV 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 13

Air Voids V A mb AV 100% 1 100% V Gmm 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 G CIVL 3137 14

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 of the specimen? CIVL 3137 15

Voids in Mineral Aggregate R AV (Air Voids) VMA (Voids in Mineral Aggregate) CIVL 3137 16

Voids in Mineral Aggregate V V 1 P V sb BE A mb b VMA 100% 1 100% mb = bulk density of compacted mixture sb = bulk density of the aggregate blend P b = asphalt binder content of mixture CIVL 3137 17

Voids in Mineral Aggregate V V G 1 P V Gsb BE A mb b VMA 100% 1 100% 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 18

Bulk Density of Aggregate Blend sb Gsb w 1 f f f G G G G 1 2 n sb 1 2 n G i = bulk relative density of aggregate i f i = fraction of blend from aggregate i CIVL 3137 19

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 20

Voids Filled with Asphalt V VTM V V VMA BE VFA 100% 1 100% 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 21

Voids in Mineral Aggregate R AV (Air Voids) VMA (Voids in Mineral Aggregate) CIVL 3137 22

Example What is the VFA of the compacted specimen from the previous examples? CIVL 3137 23

CIVL 3137 24

Asphalt Concrete Aggregate

Right Type of Aggregate Dense-graded Hard Durable Rough-surfaced Cubical (angular and equidimensional) Hydrophobic Free from deleterious substances Low Porosity CIVL 3137 26

TDOT Specifications CIVL 3137 Source: Standard Specifications for Road and Bridge Construction (TDOT, 2006) 27

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 28

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 29

TDOT Specifications CIVL 3137 30

Superpave Specifications Same as Table 6 7 Source: NCEES FE Supplied Reference Handbook CIVL 3137 31

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 32

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 33

Superpave Specifications Same as Table 6 8 Source: NCEES FE Supplied Reference Handbook CIVL 3137 34

Flexible Pavements CIVL 3137 35

Superpave Specifications Same as Table 6 8 COARSE AGGREGATE ANGULARITY Source: NCEES FE Supplied Reference Handbook CIVL 3137 36

Coarse Aggregate Angularity Fractured Face Fractured Faces Fractured Faces CIVL 3137 37 Source: http://pavementinteractive.org

Superpave Specifications Same as Table 6 8 FINE AGGREGATE ANGULARITY Source: NCEES FE Supplied Reference Handbook CIVL 3137 38

Fine Aggregate Angularity V sand RD m sand sand w V V V voids cyl sand Vvoids % Voids 100% V cyl Source: http://pavementinteractive.org CIVL 3137 39

Superpave Specifications Same as Table 6 8 FLAT AND ELONGATED PARTICLES Source: NCEES FE Supplied Reference Handbook CIVL 3137 40

Particle Shape (Flat and Elongated Particles) CIVL 3137 41 Source: http://pavementinteractive.org

Superpave Specifications Same as Table 6 8 CLAY CONTENT Source: NCEES FE Supplied Reference Handbook CIVL 3137 42

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

Superpave Specifications Source: NCEES FE Supplied Reference Handbook CIVL 3137 44

CIVL 3137 45