The qualities necessary for the grouting paste for prestressed concrete are faculty of smooth flow, little bleeding and change of volume, high strength (compressive and bond) and resisting power for freezing. But those qualties, excepting the faculty of flow, are improved by the minimum use of water. The current apparatus for measurement of fluidity of grouting paste are such as shown in Committee, in various foreign countries except in Holland. But no apparatus has been calibrated in poise so

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... ar. It is partly due to the thixotropic property of cement paste but mainly to the assumption that cement paste is nothing but a Newtonian liquid. The experiments which the writers have made with his coworkers on an assumption that cement paste is Bingham body clearly show that the measurements done with those apparatus can be expressed in terms of absolute unit. The measurement has been done by means of BH type rotation viscometer (Photo. 1) at various rates of shear, that is, its number of rotation of rotor. grouting, that is, mix proportion, types and numbers of rotation of mixer, mixing time and the fineness of cement. Several results are shown in the following figures. From these experiments some conclusions have been obtained as follows: (1) Cement paste behaves as Bingham body, and the fluidity of grouting paste is represented (2) The values of these rheological properties are influenced by mixproportion, types and numbers of rotation of mixer, mixing time and the fineness of cement etc..