Properties of Fresh Concrete



The knowledge about the property of fresh concrete enables us to study the behavior of concrete in its hardened state and adjust them accordingly in order to obtain the desired results. The different fresh properties of concrete are explained below:

1. Workability Property of Fresh Concrete
2. Segregation of Fresh Concrete
3. Bleeding of Fresh Concrete
4. Compatibility of Fresh Concrete
5. Mobility
6. Stability
7. Consistency

WORKABILITY OF FRESH CONCRETE


The basic requirements of mixability, stability, transportability, mobility, and Finishability of fresh concrete are collectively referred to as workability. It is a composite property.


According to IS:6461 (Part VII)-1973, workability can be defined as “that property of concrete, which determines the ease and the homogeneity with which it can be mixed, placed, compacted and finished.”
The ease is related to the rheology of fresh concrete, which includes the parameters of stability, mobility, and compactibility. 

The workability of fresh concrete is a complex system of two critical parameters – namely Consistency and Homogeneity. The consistency is the relative mobility or the ability of the fresh concrete to flow without segregation and bleeding. Homogeneity means the uniform and stable distribution of the cement, aggregates and the water. Hence workability is the summation of the properties like consistency and homogeneity.

Another definition for workability is the property which will determine the amount of useful internal work necessary in order to produce full compaction. 100% compaction regards to best mode of workability. Read More>>

SEGREGATION OF FRESH CONCRETE

Segregation is another important property of concrete in a fresh state. The segregation of fresh concrete can be defined as the separation of the constituent particles or material of the material. A good concrete is one in which all the ingredients of the concrete are properly distributed in order to make a homogeneous mixture. Read More>>

BLEEDING OF FRESH CONCRETE

Bleeding in concrete can be defined as the water gain. It is a particular form of segregation. It is a phenomenon in which some of the water from the concrete comes out to the surface of the concrete. It is observed in a mix which is highly wet. The rate of bleeding increases with the time. The phenomenon of bleeding is an inherent property seen in concrete. Read More>>

COMPACTIBILITY OF FRESH CONCRETE

The compactibility of fresh concrete is the ease with which the concrete can be compacted. It mainly depends on the:

1. Amount of Cement
2. Composition of the cement
3. Fineness of the cement
4. Amount of water
5. Shape and Grading of the Fine aggregates
6. Entrained air in the concrete

The addition of a certain type of admixtures and entrained air will increase the workability without increasing the slump.

MOBILITY

The mobility is the property of fresh concrete to flow into the formwork around the steel reinforcement without the occurrence of segregation or bleeding. It is the ability of the concrete to be molded.

STABILITY

The stability property of the concrete, is the ability to remain stable, homogeneous, coherent mass without segregation both during the handling, which is called as the static stability and also during the vibration, called as the dynamic stability.

CONSISTENCY

The consistency refers to the fineness of the concrete or the ease with which it flows. It refers to the mean degree of wetness. It is an indication of workability. It represents the relative mobility. 
The consistency of mixes that are used in different applications is shown in Table-1.



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