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Types of bituminous mixes

Short answer

By aggregate gradation: dense-graded, open-graded, gap-graded, mastic. By mixing temperature: hot, warm, cold. By layer use: surface course, binder/base course. By binder: bitumen, cutback, emulsion, polymer/rubber modified.

Explain bituminous mixes types.

Bituminous mixes are classified in the following ways.

1. By aggregate gradation

  • Dense-graded mixes - continuous grading from coarse to fine, with low voids; strong and impermeable. Examples: bituminous concrete (BC), dense bituminous macadam (DBM), semi-dense bituminous concrete (SDBC).
  • Open-graded mixes - mostly coarse aggregate with few fines, high voids (15-25%), good drainage but lower strength. Examples: bituminous macadam (BM), open-graded premix carpet, porous asphalt.
  • Gap-graded mixes - some intermediate sizes missing, with a high coarse and filler content and a lot of binder; e.g., stone matrix asphalt (SMA), highly rut-resistant.
  • Sand and mastic mixes - sand asphalt, mastic asphalt (fine aggregate in rich binder, used for bridge decks).

2. By mixing temperature and method

  • Hot mix asphalt (prepared at 150-165 degrees C in a hot mix plant).
  • Warm mix (100-130 degrees C using additives).
  • Cold mix (with emulsion or cutback at ambient temperature).
  • Plant mix and mix-in-place (road mix).

3. By use in the pavement

  • Surface course - BC, SDBC, premix carpet, mastic, SMA.
  • Binder/base course - DBM, BM.

4. By binder

Bitumen, cutback, emulsion, tar and polymer/rubber-modified bitumen (PMB, CRMB) mixes.

✓ Answer checked by Claude Opus 5.5 (high effort)

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