Rheological properties and the air content in fresh concrete for self compacting high performance concrete

The results of the influence of rheological properties and universal components of a fresh High Performance Self-compacting Concrete (HPSCC) on the content of entrapped air in the concrete mix are presented in the paper. The nature of changes the air content in fresh HPSCC depends on rheological parameters. When yield value g and plastic viscosity h decrease thereby diameter of slump flow increase and time of slump flow decrease then air content in mixture also decrease. The results of tests show that we can predict the influence of rheological properties (yield stress, plastic viscosity or diameter and propagation time) on air content in fresh HPSCC by statistical model presented in the text of the paper. Obtaining the air content of less than 2% of the fresh concrete is possible if the diameter of slump flow is greater than 65 cm - according to the slump-flow test (yield stress limit is less than 250 N mm - according to tests performed rheometer BT) and the time of slump flow is less than 16 s (plastic viscosity h less than 14,000 N mm s - measured by rheometer BT2).