Table of Contents
Definition
The separation of Concrete ingredients from mixed concrete is known as Segregation.
What Is Segregation Of Concrete?
Separating concrete ingredients from each other refers to concrete segregation. Concrete segregation can reduce the strength of the concrete significantly. Concrete segregation may even cause leakage in a structure.
Segregation occurs during the handling and placement of concrete. It is also happening because of too much compaction of freshly mixed concrete. In this process, cement paste comes to the top and aggregates settle at the bottom.
It highly affects the overall strength of the concrete. To pour concrete, all ingredients like water, cement, and aggregates should be mixed properly to create a homogeneous mass.
Sometimes due to erks and unnecessary vibrations, the paste of cement and sand gets separated from the coarse aggregate. If the concrete mixture is aggregated during placing, it should be remixed properly before depositing. If the initial setting time of the concrete is finished, this concrete can not be used for pouring.
Segregation can occur in three forms as given below,
- Separation of aggregate from the concrete.
- Separation of cement from the concrete.
- Separation of water from the concrete.
All the ingredients in the concrete should mix homogeneously for better workability and consistency.
Causes Of Segregation In concrete
- Difference between the specific gravity of cement and coarse aggregate.
- Excessive vibration in the concrete.
- Pouring concrete from more than the 1-meter height.
- By mixing poorly
Types Of Concrete Segregation
There are two main types of segregation in concrete:
1. Segregation caused by the separation of aggregates
This type of segregation occurs when the concrete mix is too dry. When the amount of water added to the mixture is lower than what is required to achieve the desired consistency, the coarser elements in the mix tend to separate and settle more quickly than the finer elements.
2. Segregation caused by the separation of cement slurry
If the mixture of concrete is too wet, the cement slurry can separate from the rest of the material. This happens when the concentration of water in the cement is higher than what is required in the mixture. Cement slurry is a mixture of cement and water.
Achieving the perfect proportion of concrete mix is crucial in increasing the workability of concrete. Workability is the most important variable when it comes to concrete. A workable concrete mix will result in durable concrete, which in turn leads to a higher life expectancy for a structure. Strong pillars are crucial for a solid foundation of a house, and using durable concrete is essential in achieving this. Weak concrete can cause a structure to become unstable and may result in its demolition.
Concrete Segregation Effects
Some of the major issues caused by concrete segregation are discussed below.
1. Leakage and corrosion problems
Segregation results in the formation of pores in the concrete, which can cause water leakage. This leakage can lead to corrosion, which can have a direct impact on the building’s structure. Continuous water leakage weakens the building from the inside, making it vulnerable to damage.
2. Formation of cracks
Concrete strength decreases due to segregation, resulting in visible cracks on slabs, columns, or other affected areas. Cracks on beams and columns indicate that segregation is occurring and can be a warning sign of potential danger to the building’s structure.
3. Decreased concrete strength
The strength of concrete is a critical factor in ensuring a building’s stability. Improper concrete ratios result in a loss of strength and can lead to the formation of cracks and leakage problems. The columns and beams bear the weight of the entire structure, and the effects of segregation are most visible in these areas.
Therefore, it is essential to ensure that concrete mixtures are prepared correctly to avoid the negative effects of segregation.
How To prevent Segregation In Concrete?
- By adding admixtures.
- By adding pozzolana.
- By mixing the air-entraining agent.
- By maintaining the proper ratio of ingredients in the mixed concrete.
- By extensive taking care of transportation, placing of concrete.
Concrete Segregation Vs Bleeding
Segregation and bleeding are two distinct phenomena that can affect the properties of concrete. It is important to understand the difference between them. Some people tend to use these terms interchangeably, but they are not the same.
Segregation occurs when the aggregates in the concrete mix separate from the cement slurry. This can happen due to the excessive fall of the concrete during pouring or improper mixing of the elements. On the other hand, bleeding occurs when water in the concrete mix separates and rises to the surface. This can be caused by adding too much water or excessive vibration.
The consequences of segregation and bleeding are also different. Segregation can make the concrete porous and weak, whereas bleeding can result in a honeycomb appearance on the surface of the concrete.
When segregation occurs, it is challenging to repair the damage after the concrete has set. In contrast, there is no way to repair bleeding once it has formed.
Therefore, it is essential to take preventive measures to avoid both segregation and bleeding. Careful mixing, proper placement, and adequate curing can prevent these problems and ensure that the concrete achieves its desired properties.
Frequently asked questions
Bleeding is a type of segregation in which water separates from concrete. Water collects on the top surface of the concrete and the cement-aggregate mixture settled down. The reason behind this is the low gravity of water compared to cement and aggregate.
The main cause of bleeding is the high water/cement ratio.