Fresh Concrete or Plastic Concrete is a Freshly mixed material which can be moulded to any shape. The performance requirements of hardened concrete are more or less well-defined shape with respect to the shape, finish, strength, durability, shrinkage and the Creep. To achieve these objectives economically, the fresh concrete should satisfy a number of requirements from the mixing stage till it is transported, placed in the formwork and compacted.
The basic requirements of fresh concrete used in construction are:
- Mobility or Flowability
The mix should be able to produce homogeneous fresh concrete from the constituent materials of the batch under the action of the mixing forces. A less mixable concrete mix requires more time to produce a homogeneous and uniform mix. This property is called as mixability.
The mix should be stable such that it should not segregate during transportation and placing, when it is subjected to forces during handling operation. The Tendency of hardening should be minimum.
The mix should be cohesive and sufficiently mobile to be placed in the form around the reinforcement and should be able to cast into the required shape. This property is called as Flowability or Mobility.
The compatibility is the property which ensures the dense and the compacted concrete with minimum voids.
The concrete must be possible to attain a satisfactory surface finish without honeycombing or the blowing of the holes from the formwork. This capability of concrete is called as Finishability.