Bituminous emulsions in highway works — typical applications In flexible pavement construction and maintenance, bitumen emulsions are mainly used in:

Introduction / Context:
Bitumen emulsions are dispersions of bitumen in water stabilized by emulsifiers. They allow cold application, making them particularly suitable for certain surface treatments and maintenance tasks without the need for heating to high temperatures.

Given Data / Assumptions:

• Standard practice in flexible pavements.
• Ambient-temperature application desirable for thin treatments.
• Choice of cationic/anionic grade depends on aggregate chemistry and climate.

Concept / Approach:
Surface dressing (chip seal) involves spraying a binder onto an existing surface and immediately spreading cover aggregate. Emulsions are ideal because they wet aggregates at ambient temperatures, break and set adequately, and reduce fire risks. While emulsions are also used in patching, tack coats, fog seals, and slurry seals, the classic “main” use highlighted in many exam syllabi is surface dressing.

Step-by-Step Solution:
1) Identify processes needing thin, uniformly spread binder at low temperature.2) Recognize surface dressing as the archetypal emulsion application.3) Note that dense hot mixes (bitumen macadam, asphaltic concrete) typically employ hot binders, not emulsions.4) Select “surface dressing”.

Verification / Alternative check:
Agency manuals list emulsions for surface dressing, tack/fog seals, and maintenance; hot mixes normally use heated paving-grade bitumen or modified binders.

Why Other Options Are Wrong:
“Patching and maintenance operation” is indeed a common use, but the question asks mainly used; exams typically expect “surface dressing”. “Bitumen macadam” and “asphaltic concrete” are hot-mix processes.

Common Pitfalls:
Assuming emulsions are interchangeable with hot binders in dense-graded mixes; ignoring curing time for emulsion break and set before trafficking.

Final Answer:
surface dressing