Asphalt Concrete Properties

Transcription

1 Asphalt Concrete Properties

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

3 Mix Volumetrics CIVL

4 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

5 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

6 Bulk Volume Aggregate Particle Water Permeable Voids CIVL

7 Net Volume Aggregate Particle Water Permeable Voids CIVL

8 Effective Volume Aggregate Particle Absorbed Asphalt Water Permeable Voids CIVL

9 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

10 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

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

12 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

13 Air Voids V A mb AV 100% 1 100% V mm mb = bulk density of compacted mixture D Bulk Specific Gravity and Density of Compacted Bituminous Mixtures mm = maximum density of the mixture D Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures CIVL

14 Air Voids V A mb AV 100% 1 100% V Gmm G mb = bulk specific gravity of compacted mixture D Bulk Specific Gravity and Density of Compacted Bituminous Mixtures G mm = maximum specific gravity of the mixture D Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures G CIVL

15 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

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

17 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

18 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

19 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

20 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

21 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

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

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

24 CIVL

25 Asphalt Concrete Aggregate

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

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

28 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

29 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

30 TDOT Specifications CIVL

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

32 19-mm Gradation Example 100 Percent Passing (%) Opening Size (mm) Raised to the 0.45 Power CIVL

33 19-mm Gradation Example 100 Percent Passing (%) Opening Size (mm) Raised to the 0.45 Power CIVL

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

35 Flexible Pavements CIVL

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

37 Coarse Aggregate Angularity Fractured Face Fractured Faces Fractured Faces CIVL Source:

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

39 Fine Aggregate Angularity V sand RD m sand sand w V V V voids cyl sand Vvoids % Voids 100% V cyl Source: CIVL

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

41 Particle Shape (Flat and Elongated Particles) CIVL Source:

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

43 Clay Content (Sand Equivalent Test) Hsand SE 100% H clay H sand H clay Source:

44 Superpave Specifications Source: NCEES FE Supplied Reference Handbook CIVL

45 CIVL