PURPOSE: To obtain a homogenous and dense cured body having a smooth surface without generating pitting and cavities to a plastic body, by keeping the balance between the moisture moving speed in a composition and the drain speed from a sheet to uniformize moisture distribution.

CONSTITUTION: A sheet has such a structure that two different layers are laminated and bonded and one of two layers is a porous resin layer (a) having a contact angle θ with water of 10° or more and a pore size of 0.01W100 μm. This resin layer dominantly acts on the removal of the excessive moisture and air in cast concrete. When the contact angle with water of this resin layer is smaller than 10°, the balance of the discharge and movement of moisture and air is hardly held even if a particle size is changed variously. It is necessary that the pore size of the pores provided to the resin layer is 0.01W100μm, pref., 0.05W10μm from such an aspect that said balance should be held. When the pore size becomes smaller than 0.01μm, the discharge of air is difficult. When the pore size becomes larger than 100μm, the discharge of moisture becomes much and it is not pref., because the clogging of cement particles is generated.