چكيده به لاتين
Due to the composition, the production of self-compacting concrete (SCC) requires more mixing energy to uniform and homogenize the concrete components. This limits the rate of concrete production in comparison with convectional concrete and therefore is an important financial factor. So mixing energy (mixing time and power) is the main factor in concrete production and before large production, the appropriate mixing time and speed should be determined for each mixture.
In this study, according to objectives and considering that mixing time and speed are two main factors in content of mixing energy and according to guidelines and regulations, two SCC mix designs (poweder type and VMA type) were mixed in three mixing times (3, 8 and 11 minutes) and each of them in two mixing speeds (20 and 40 RPM) and their effect on rheological properties was evaluated.
The results showed that in each series of mixtures by increasing the mixing time up to a certain level that is called stabilization time (the shortest mixing time) and in this study is 8 minutes, the workability of concrete increases and after that by mixing up to 11 minutes it decreases 6 percents.Static and dynamic yield stress in the 8 minutes mixing have the minimum amounts too and this amount is different from each parameter to another, so the rheology tests also confirm these results.
Keywords: mixing time, mixing speed, mixing energy, stabilization time