摘要：Nowadays, workability is absolutely necessary for piping concrete, which is influenced by characteristics of structure of fresh cement paste. In this paper, the movement of particles in electric field and flocculent units at different W/C were observed, and rheologic characteristics of fresh cement paste at different W/C and the pastes with naphthalene sulphonate (NS) and poly carboxylate (PC) superplasticizers were investigated using rotational viscometer (NXS-11A). It is found that at initial hydration age cement particles carry different electric quantity and electrical property; increment of W/C induces flocculent units more separated, less hysteresis loop area and lower crush point; application of superplasticizers brings much less loop area and indistinct crush point. It is concluded that 1) fresh cement paste is filled with flocculation units of different strength; 2) different units are connected with one another loosely; 3) tunnels for bleeding form in the weakest connecting area. Water can disperse flocculent units to some extent, especially for superplasticizers. However, the latter can’t separate flocculation of cement particles completely.
其他摘要：Nowadays, workability is absolutely necessary for piping concrete, which is influenced by characteristics of structure of fresh cement paste. In this paper, the movement of particles in electric field and flocculent units at different W/C were observed, and rheologic characteristics of fresh cement paste at different W/C and the pastes with naphthalene sulphonate (NS) and poly carboxylate (PC) superplasticizers were investigated using rotational viscometer (NXS-11A). It is found that at initial hydration age cement particles carry different electric quantity and electrical property; increment of W/C induces flocculent units more separated, less hysteresis loop area and lower crush point; application of superplasticizers brings much less loop area and indistinct crush point. It is concluded that 1) fresh cement paste is filled with flocculation units of different strength; 2) different units are connected with one another loosely; 3) tunnels for bleeding form in the weakest connecting area. Water can disperse flocculent units to some extent, especially for superplasticizers. However, the latter can’t separate flocculation of cement particles completely.
