The Design and Operation of Central Mixing Plants-A Symposium


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Title: The Design and Operation of Central Mixing Plants-A Symposium

Author(s): ACI Committee 603

Publication: Journal Proceedings

Volume: 26


Appears on pages(s): 551-579

Keywords: none

Date: 3/1/1930

Comments on the design and operation of ready-mixed concrete plants Author discusses briefl cation, equipment, and the problems of plant lo- plant operation. Water control of a commercial control-mixing plant To insure accuracy in admitting the predetermined quantity of mixing water to be added to a batch there has been used successfully an enclosed, central syphon measuring tank equipped with a mechanical interconnection between inlet valve, outlet valve, and batch hopper gate, whereby the operator cannot ad- mit more or less water than the quantity for which the measuring tank is set. Notes from l xperionco in mixing plant operation Problems encountered in the operation of central mixing plants and the solutions at one plant are de- scribed. Storage of aggregate, conveyor systems for bulk cement, mixers, trucks, mix design, and control and peak loads are topics covered. Recent developments and trends in the comnnrcIal concroto business Central mixing plants, for the purpose of this study, 1928-1930, were classed as plants for producing com- mercial ready-mixed concrete. Growth of such plants quadrupled in that period: their annual production ranged’ from 3600 to ‘I 15,000 cu yd; and a total U. S. output of 5.000,OOO cu vd of ready-mixed concrete valued at nearly $45,000,000 was indicated by the end of 1929. A strong trend was noted toward the dry plant system of central proportioning and mixing in transit, apparently based on sound operating practice and concrete control. The use of control mixing plants by tho Port of N. Y. Authority Six central mixing plants and I I batching plants used by the Port of New York Authority are described. In the operation of the plants the proportions to be used and the amount of water were fixed by the results of preliminary tests of the aggre ates and cement used on each job. Test methods an d scribed. specifications are de