Shrinkage of Concrete

The overall shrinkage of concrete depends upon the materials of concrete, size of the member and environmental situation and atmospheric condition .For a particular and specific humidity and temperature condition the total shrinkage value of concrete is very much influenced by the total amount of water present in the concrete at the time of mixing of concrete and also by the cement content.

The approximate value of total shrinkage strain for design of RCC structure may be taken as 0.0003.

Creep of Concrete

Creep value of concrete generally depends in addition of factors of shrinkage , on the stress in the concrete, age at loading and duration of load of loading. As long as whenever stress in concrete does not exceed one third of its characteristics compressive strength, the creep value of concrete may be assumed to be the proportional to the stress.

Age of loading             Creep co efficient

7 days                                    2.2

28 days                                  1.6

365 days                                1.1

In the absence of experimental value and detail information on the effect of the variables, the ultimate creep strain value may be estimated from the value as noted above. It also may be noted that the ultimate creep strain estimated  as described above does not include the elastic strain.