Properties of Fresh Concrete:
The first 48 hours are very important for the performance of the concrete structure.
It controls the long-term behavior, influence f'c (ultimate strength), Ec (elastic modulus), creep, and durability.
Properties of Fresh Concrete :
Properties at Early Ages :
• Slump Loss
• Plastic Shrinkage
• Time of Set
àDefinition: Effort required to manipulate a concrete mixture with a minimum of segregation.
It is not a fundamental property of concrete.
I) consistency (slump)-- easy to flow
II) cohesiveness --tendency to bleed and segregate
àSlump test is a test conducting before concrete to be used for casting. The purpose of slump test Is to determine the water content in concrete and its workability
àConsistency or fluidity of concrete is an important component of workability and refers in a way to the wetness of the concrete.
However, it must not be assumed that the wetter the mix the more workable it is. If a mix is too wet, segregation may occur with resulting honeycomb, excessive bleeding, and sand streaking on the formed surfaces.
On the other hand, if a mix is too dry it may be difficult to place and compact, and segregation may occur because of lack of cohesiveness and plasticity of the paste.