Dongyeop Han

Effect of pre-mixed cement on the dispersion of silica fume in ternary blended cementitious paste

Abstract The objective of the research presented herein was to investigate experimentally the effect of pre-mixing on ternary blended cement paste with an emphasis on the dispersion of silica fume for improved workability. Three different types of silica fume were prepared and the workability of each was tested using various workability measurement tests, specifically designed for cement paste. SEM observation confirmed that the new pre-mixing method using silica fume provided well-dispersed silica fume particles. In addition, the workability of each cement paste showed improvement when compared to standard mixing methods. Based on these results, the authors present new fundamental data for developing pre-mixed cement with improved workability.

Effect of Emulsified Refine Cooking Oil and Expandable Microsphere on Durability of High-Volume Blast Furnace Slag Concrete

In this paper, a series of experiments was conducted to evaluate the resistibility of carbonation and freeze-thawing damage of the high-volume blast furnace slag concrete using expancel, the expandable microsphere, and ERCO, emulsified refine cooking oil. The concrete mixture of 0.45 water-to-binder ratio with 60% of blast furnace slag was evaluated for carbonation, freeze-thawing resistibility, SEM, and porosity. According to the previous research, replacing ERCO contributes on improving carbonation resistibility with capillary pore filling effect by soap foaming reaction of ERCO while significantly decreased freeze-thawing resistibility. To improve this decreased freeze-thawing resistibility, expancel was used, and thus freeze-thawing resistibility was improved as the replacement ratio of expancel was increased. It is considered that the selective volume shrunken effect of expancel due to the external pressure and decreased air void spacing factor due to expancel.