It is well known that early-age macroscopic volume reduction of cementitious material after final setting, i.e.autogenous deformation, plays an important role in crack formation and crack propagation in cement paste,mortar and concrete.In past researches, the elastic deformation caused by self-desiccation of the hydrating cement paste was always considered as the major source of autogenous deformation.In fact, however, the early-age cement paste is a visco-elastic material and the autogenous deformation has to be divided into two parts, the elastic and plastic deformation.The plastic part is also very important for the early-age autogenous shrinkage.The elastic part of autogenous deformation has been studied by many researchers already.However,only few consideration has been given to the plastic part, i.e.creep.