---
title: "Define bitumen premixes"
subject: "Transportation Engineering I"
chapter: 6
key: "semester_6/transportation_engineering_i:define-bitumen-premixes"
source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/define-bitumen-premixes
site: BCT Engineering
---

# Define bitumen premixes

Transportation Engineering I · Chapter 6: Highway Materials

- Asked in: 2075 Bhadra; 2075 Baisakh; 2070 Bhadra; 2069 Bhadra; 2064 Poush (old course), 2 marks (asked 5 times)
- Video: [What is Open Graded Premix Carpet (O.G.P.C.) | Construction Process of Open Graded Premix Carpet](https://www.youtube.com/watch?v=eXZCfBvKgCg) — The Institute of Construction Managment 
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/define-bitumen-premixes
- Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-6

## Question

Define bitumen premixes (bituminous mixes) and state their types.

## Short answer

Bituminous premixes are mixtures of graded aggregates and bituminous binder mixed before laying, then spread and compacted to form base or surface courses. Types include dense-graded (BC, DBM, SDBC), open-graded (BM, PC), gap-graded (SMA), sand mixes; hot/warm/cold mix by temperature; plant mix or mix-in-place; and by binder type (bitumen, cutback, emulsion, modified).

## Answer

#### Definition
**Bituminous premixes** (bituminous mixes) are mixtures of graded aggregates and a bituminous binder that are mixed (at a plant or in place) *before* laying, and then spread and compacted on the road to form a base or surface course. Examples: bituminous macadam, dense bituminous macadam, bituminous concrete.

#### Types
1. By aggregate gradation:
   - **Dense-graded** (continuous grading): bituminous concrete (BC), dense bituminous macadam (DBM), semi-dense bituminous concrete (SDBC).
   - **Open-graded**: bituminous macadam (BM), open-graded premix carpet (PC).
   - **Gap-graded**: stone matrix asphalt (SMA).
   - **Sand mixes**: sand asphalt, mastic asphalt.
2. By mixing temperature:
   - **Hot mix** (binder and aggregate mixed at 150-165 degrees C),
   - **Warm mix**,
   - **Cold mix** (emulsion or cutback with aggregates at ambient temperature).
3. By the place of mixing:
   - **Plant mix** (hot mix plant, drum mixer) - best quality control,
   - **Mix-in-place** (road mix) - for low-volume roads.
4. By binder: bitumen, cutback, emulsion, tar and modified bitumen mixes.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What are bituminous premixes?
   A. Aggregates and binder mixed before laying, then spread and compacted
   B. Binder sprayed after laying aggregate
   C. Only cement concrete
   D. Soil stabilised with lime
   Answer: A. Premixes are prepared before laying, at a plant or in place. (Key point: Definition)

2. Which is a gap-graded mix?
   A. Stone matrix asphalt
   B. Bituminous concrete
   C. Dense bituminous macadam
   D. Bituminous macadam
   Answer: A. SMA is gap-graded; BC and DBM are dense-graded, BM is open-graded. (Key point: Gradation types)

3. Which is a cold mix?
   A. Emulsion or cutback mixed with aggregate at ambient temperature
   B. Binder and aggregate at 150-165 degrees C
   C. Warm mix
   D. Plant hot mix
   Answer: A. Cold mixes use emulsion or cutback at ambient temperature. (Key point: Mixing temperature)

## Related in Transportation Engineering I

- [Desirable properties of bituminous mixes](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Abituminous-mix-desirable-properties) — Transportation Engineering I, chapter 6, asked 3×
- [Types of bituminous mixes](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Abituminous-mix-types) — Transportation Engineering I, chapter 6
- [Types of bitumen and bituminous materials](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Abitumen-types) — Transportation Engineering I, chapter 6, asked 6×
- [Viscosity test of bitumen](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aviscosity-test) — Transportation Engineering I, chapter 6, asked 2×