What is Concrete and what properties Fresh concrete should have and should not have

What is Concrete and what properties Fresh concrete should have and should not have

What is Concrete?

Concrete is a composite mixture of fine aggregate (usually sand), coarse aggregate (usually stone ballast) and binding material (usually Portland cement) mixed together with a required proportion of water, which hardens over time.

Sometimes suitable admixtures are mixed with concrete to enhance certain properties of concrete like workability, setting time and heat production.

Properties of Fresh Concrete Should have –

Fresh Concrete is the concrete when it is still in plastic stage i.e. not yet set. must have some properties to mold it into a shape we want, These properties are listed below –

• Workability:  

  Fresh Concrete should have good workability. Workability is defined as the ease with which it can be mixed, transported and placed in position in a homogeneous state. The workability of concrete depends on the quantity of water, percentage of fine aggregate, and grading of aggregates. For heavily reinforced concrete more workable concrete required than lightly reinforced concrete.

Properties of Fresh Concrete Should not have –

• Segregation:

Segregation of Concrete results in the honeycomb in concrete as well as loss of strength in hardened concrete. Honeycomb is the breaking of Cohesion i.e. separation of coarse aggregate from the mass of concrete.

• Bleeding :

Bleeding of  Concrete is also very harmful to concrete. Bleeding happens when water or water-cement mixture separates from fresh concrete mix. Bleeding results in exposed aggregate surface and less strength in the hardened concrete. bleeding occurs when water cement ration in fresh concrete is much more than usual.