PURPOSE: To uniformize the quality of material by employing a suspension of activated clay comprising extremely fine plasticizing particles for kneading in production of a light-weight concrete for water floating construction made up of foaming resin particles as the aggrigate.

CONSTITUTION: In the production of a light-weight concrete made up of foaming resin particles as aggrigate, used for buiding a water floating construction, a suspension of activated clay comprising fine plasticizing particles is employed for kneading to enhance the consistency thereof without impairing complete hydration of cement. Increased sticking force on the surface of non-water absorbing foaming particles provides a floating concrete with an uniform quality of material.