Material Mix Design
Aggregate gradation, bitumen content, and volumetric properties per ASTM D3515 / AASHTO M323
Coarse Aggregate
> 4.75 mm (No. 4)
Fine Aggregate
0.075 - 4.75 mm
Mineral Filler
< 0.075 mm (No. 200)
CA Angularity
> 95% (1 face)
Flat/Elongated
< 10% (5:1)
Performance Grade
PG 64-22 / PG 76-22
Binder Content Range
4.5% - 6.5%
Dust/Asphalt Ratio
0.6 - 1.2
Anti-Strip Agent
0.5-1.0% (if req'd)
Target Air Voids
4.0% (Ndesign)
Gmm (Rice)
Per ASTM D2041
Gmb (Bulk)
Per ASTM D2726
| Sieve Size |
Superpave 12.5mm |
Superpave 19mm |
Marshall 12.5mm |
Marshall 19mm |
| 19.0 mm | 100 | 90-100 | 100 | 90-100 |
| 12.5 mm | 90-100 | < 90 | 90-100 | < 90 |
| 9.5 mm | < 90 | > 90 | < 90 | > 90 |
| 4.75 mm | > 90 | > 90 | > 90 | > 90 |
| 2.36 mm | 32-67 | 28-58 | 44-74 | 35-65 |
| 1.18 mm | > 90 | > 90 | > 90 | > 90 |
| 0.075 mm | 2-10 | 1-7 | 2-8 | 2-8 |
Mix Design Procedure
- Select aggregate sources and perform blend gradation (ASTM D3515)
- Determine design traffic level (ESALs) and select Ndesign gyrations
- Prepare trial blends at 3-4 binder contents (0.5% increments)
- Compact gyratory specimens to Ninitial, Ndesign, Nmax
- Measure Gmm (Rice) and Gmb (bulk) for each blend
- Plot volumetric curves and select optimum binder content at 4% Va
- Verify all criteria at optimum: VMA, VFB, DP, stability, moisture
- Run TSR (AASHTO T283) - minimum 80% retained strength
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