Investigation of the interaction of paste phase with chemical admixtures in self-consolidating concrete

Rapid development of admixture technology has accelerated the development of concrete technology. The self consolidating concretes (SCC) were put into practice by developing polycarboxylate-based chemical admixtures. This interaction of polycarboxylate based admixtures with powder materials within the concrete at nano and micro levels affects the fresh and hardened characteristics of the concrete at meso and macro levels. In the present study, the interaction of powder material paste with admixtures in the SCC was investigated at nano-micro and meso levels. In addition, a number of concrete tests were performed at macro level. %10, %20, %30, and 40% of blast furnace slag (BFS) were substituted with cement for reference samples while %10, %15, %20, and %25 of calcite were added to the cement. Zeta potential values of powder material paste were obtained at micro level; scanning electron microscope (SEM) analysis of hardened powder material paste was performed. Rheological features and mini distribution values of powder material paste were identified at meso levels. For concretes prepared at macro levels, consistency of fresh state, stability of consistency, specific bulk density, L-box test, compressive strength of hardened concrete samples on days 1, 3, 7, 28, and 90 were found. Consequently, the results of the zeta potential of powder materials paste showed serious differences. The reason for this situation is the fact that the grain sizes of powder materials tested were rather large compared to this testing method. When the plastic viscosity results of powder materials paste obtained in accordance with the Bingham model were assessed, powder materials paste, the plastic viscosity of which is close to value of 1 Pa.s (± 100 mPa.s), were observed to be more resistant to segregation and to form a homogeneous permeation state /consistency, and their L-box test passing ratio was also determined to be homogeneous and high. It will be possible to carry out the production of the ideal SCC with the powder material paste mixtures having a 1 Pa.s (± 100 mPa.s) viscosity and a mini flow(permeation) diameter larger than 200 mm. With the increase in the calcite admixture, the meso level plastic viscosity results showed increase, and the passing capacity through the macro level reinforcements was determined to have increased, as well.