EVALUATION OF THE CEMENT PASTE THIXOTROPY
The use of most recent admixtures enables to cast highly fluid concrete placed without vibration. However this type of concrete remains relatively difficult to formulate properly.When fluidity is too high, the homogeneity of the concrete is adversely affected due to a granular sorting phenomenon called segregation: a too much fluid cement paste results in the settling of the granular skeleton (coarse aggregates) and rising of the fluid matrix to the surface. By providing additional resistance to prevent particles from segregating, thus enhancing the stability of the cement - based materials, the thixotropy is of particular interest in the field of civil engineering.To have a more accurate study of the rate of internal structural breakdown, the present study proposes a semi-empirical procedure comparing systems with different viscosities. For this approach, tests were conducted on SCC pastes. Results suggest different critical dosage of VMA. To obtain the greatest thixotropy of the mixture, a maximum value of VMA dosage appears. Beyond this value, the tridimensional networks of these more concentrated mixtures are highly structured and thus more difficult to deform by agitation.
Thizotropy Viscosity Modifying Admiztures Cement paste Ezperimental protocol Superplasticizers
B.Helnan-Moussa J.Y.Petit Y.Vanhove E.Wirquin
Laboratoire dArtois Mrcanique, Thermique et Instrumentation, Brthune, France
国际会议
长沙
英文
526-533
2009-06-05（万方平台首次上网日期，不代表论文的发表时间）