AMOUNT of water present in the concrete at the time of mixing and, to a lesser extent by the cement content.In absence of test data, the approximate value of shrinkage strain for design shall be considered as -For pre-tensioning = 0.0003For post-tensioning = \(\frac{0.0002}{\log(t+2) }\)Where, t - age of concrete at transfer in days.The value of shrinkage strain for the design of post-tensioned concrete may be INCREASED by 50 percent in dry atmospheric conditions, subject to a maximum value of 0.0003.As per IS1343:2012, cl. 6.2.4.The total shrinkage strain is COMPOSED of two components, the autogenous shrinkage strain and the drying shrinkage strain.The value of the total shrinkage strain is given by -\(ϵ_{cs}= ϵ_{CD}+ϵ_{ca}\)Here,ϵcd - Drying shrinkage strainϵca - Autogenous shrinkage strain.Drying shrinkage strainAutogenous Shrinkage strainThe drying shrinkage strain develops slowly, as it is a function of migration of the water through the hardened concrete.The autogenous shrinkage strain develops during the HARDENING of concrete; the major part develops in the early days after casting.Autogenous shrinkage is a linear function of concrete strength.It should be considered specifically when new concrete is cast against hardened concrete.