Rheology of High-Performance Concrete-Effect of Superplasticizer and Silica Fume
R. Duval, E. H. Kadri, J. P. Bigas, and W. Luhowiak
Appears on pages(s):
admixture (water-reducing); concrete (high-performance); consistency;
silica fume; superplasticizer
This paper deals with the consistency of High-Performance Concrete. Three water-reducing admixtures and two cements were tested by casting sixteen series of silica fume concretes. The study of the consistency was investigated as a function of time by using slump test and its comparison with heat flow measurement. The W/C are 0.25 and 0.35, and the amount of silica fume varies between 0 and 30% as a partial replacement of cement mass Two cements with different C3A, contents are used. The influence of the admixture chemistry was studied using polynaphthalene, polymelamine and polyvinyl superplasticizers. The results indicate that the polynaphthalene admixture is the most efficient one to control the consistency of concrete. Nevertheless polymelamine shows better fluidification properties than polyvinyl. Concerning the effect of silica fume, the results show that a partial replacement up to 10% silica fume does not reduce concrete workability. The increase in silica fume content corresponds to a quicker slump loss with time. Correlation between slump test results and heat flow measurements indicates that silica fume has an accelerating effect on the first hydration reactions and leads to a quick modification of the consistency of concrete. About the cement type, it has been noticed that the total amount of admixture is linked to the C3A content.