Importance of Mixing time for concrete is as follows:
It is important to know the minimum mixing time necessary to produce a concrete of uniform composition, and of reliable strength.
The mixing time or period should be measured from time all the cementing materials and aggregates are in mixer drum till taking out the concrete.
Mixing time depends on the type and size of mixer, on the speed of rotation, and on the quality of blending of ingredients during charging of the mixer. Generally, a mixing time of less than 1 to 1.25 minutes produces appreciable non-uniformity in composition and a significant lower strength; mixing beyond 2 minutes causes no significant improvement in these properties.
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