Bleeding and initial setting time

Bleeding

The measured bleeding (DS 423.18) of the concretes is shown below. Portland cement based concretes did not bleed, whereas bleeding was observed for all the concretes containing slag. There was visible bleed-water on top of the large and small blocks and the cylinders that had hardened in a horizontal position showed evidence of water having moved to the high point along the curve cylinder surface.

Initial setting time

The measured initial setting time (DS 423.17) of the individual concrete types is shown below. The Portland cement based concretes generally show shorter setting times than slag based concretes.

The setting time of SCC seems longer than that of the corresponding slump concretes. It is tempting to assume that this observation could be due to higher concentration of superplasticizing admixture in the SCCs. However, the superplasticizer concentration is in fact only slightly higher in Mix D compared to Mix C and in Mix M compared to Mix K. While the concentration of superplasticizer in Mix F and Mix J is virtually identical at 0,812 and 0,816 % of powder respectively.