---
title: "Segregation and bleeding; control during placing"
subject: "Concrete Technology and Masonry Structure"
chapter: 3
key: "semester_5/concrete_technology_and_masonry_structure:segregation-bleeding-control"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/segregation-bleeding-control
site: BCT Engineering
---

# Segregation and bleeding; control during placing

Concrete Technology and Masonry Structure · Chapter 3: Mix design of concrete and property of green concrete

- Asked in: 2080 Bhadra, 3+3 marks
- Video: [2.8  Segregation of Concrete](https://www.youtube.com/watch?v=mTHLeQMLzlE) — Interesting Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/segregation-bleeding-control
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-3

## Question

Define segregation and bleeding. How will you control segregation during placing of concrete?

## Short answer

Segregation is separation of mix constituents causing non-homogeneity; bleeding is water rising to the surface. Control segregation by limiting free fall to 1.5 m, placing near final position, using layers 300-450 mm with prompt compaction, well-graded cohesive mix, proper slump, chutes with baffles, tight formwork, and re-mixing if needed.

## Answer

**Segregation** is the separation of the constituents of a fresh concrete mix, so that the mix is no longer homogeneous: the coarse aggregate separates from the mortar, or the paste separates from the aggregate. It results in honeycombing, weak and non-uniform concrete.

**Bleeding** is a form of segregation in which part of the mixing water rises to the surface of freshly placed concrete as the heavier solids settle. It forms a water layer (and laitance) on the surface, and water pockets under aggregate and bars, weakening the concrete.

#### Controlling segregation during placing
1. **Limit the free fall** of concrete to 1.5 m; use chutes, drop pipes (elephant trunk) or a tremie for deeper placing.
2. Place concrete as near to its final position as possible and do not use a vibrator to move it over long distances.
3. Place in layers of 300-450 mm and compact each layer promptly; avoid over-vibration.
4. Use a well-graded aggregate, a suitable cohesive mix with enough fines, and not too high a slump (use superplasticiser instead of water); consider air entrainment.
5. Keep chutes at proper slope (and use baffles at the end) and avoid discharging against formwork or reinforcement.
6. Use tight formwork that does not leak the paste; make a barrier or hopper at the discharge end to receive concrete.
7. Re-mix if segregation has occurred before placing.

## Check yourself

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

1. Segregation means
   A. water rising to the surface
   B. separation of constituents so the mix is no longer homogeneous
   C. volume loss on drying
   D. setting too fast
   Answer: B. Coarse aggregate separates from mortar. (Key point: Segregation)

2. Bleeding is
   A. coarse aggregate sinking only
   B. cracking from heat
   C. rise of mixing water to the surface as solids settle
   D. loss of cement
   Answer: C. It is a form of segregation where water rises. (Key point: Bleeding)

3. Free fall of concrete during placing should be limited to
   A. 5 m
   B. 3 m
   C. no limit
   D. 1.5 m
   Answer: D. Use chutes or tremie for greater depth. (Key point: Free fall)

## Related in Concrete Technology and Masonry Structure

- [Define shrinkage, creep, segregation, bleeding](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ashrinkage-creep-segregation-bleeding-define) — Concrete Technology and Masonry Structure, chapter 3
- [Segregation and bleeding with causes](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Asegregation-bleeding-causes) — Concrete Technology and Masonry Structure, chapter 3
- [Segregation: forms and control](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Asegregation-forms-control) — Concrete Technology and Masonry Structure, chapter 3, asked 4×
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