ABSTRACT
The 1965 edition of the Swedish Regulations Governing Concrete Structures: Materials and Workmanship-Concrete (BfB B5-1965) prescribes that the mixing time for concrete shall be at least 1.5 minutes (90 seconds). A wide variety of methods have been employed in efforts to determine the mixing capacity of concrete mixers. Most of these rely on measurements of the variations of one or more properties, for example:
consistence unit-weight of concrete
unit-weight of air-free mortar air content
content of fine and coarse aggregate cement content water content compressive strength.
