Abstract
It has been found that properties of fresh cement paste are remarkably changed by devided addition and subsequent devided mixing of water for the same mix proportion (this method has been referred as double mixing.). It is strongly suggested that some surface chemical interaction between cement and water is related to this phenomenon. But this has not been elucidated completely yet.
In this paper, mechanism of these double mixing effects and influences of double mixing method on bleeding and rheological property of cement paste were experimentally investigated. From these experiments it was suggested that the double mixing effect is not only associated with physico chemical interaction between water and cement powder but also with chemical reaction of cement particles with water and electrostatic charge (zeta potential) of cement particles that might be related to the early stage chemical reaction of cement with water.
