Title: Revised Application Of Fineness Modulus In Concrete Proportioning
Author(s): Henry L. Kennedy
Publication: Journal Proceedings
Appears on pages(s): 597-614
Presents a method of concrete proportioning in which trial mixes are used only for the final adjust- ment of mix parts. Fineness modulus is used only as a measure of effective fineness of combined aggregate to facilitate testing and control. Actual tests for com- pressive strength or other properties are used as a reliable check of the mix. Preference is given to the use of water-cement ratio as the first step in the de- sign. When the fineness of combined aggregate is expressed in terms of fineness modulus instead of as gravel-sand ratio, a single determination of opti- mum fineness serves for all reasonable gradations of fine or coarse aggregates of a given type and maxi- mum size. Optimum fineness is determined from com- pression tests on a series of concretes of fixed cement content and substantially equal workability. The con- crete in this series which gives maximum strength seems to define the coarsest and most economical mix from which fully satisfactory concrete can be made. Charts are provided for use only in selecting fineness modulus where the making of compression tests is not feasible prior to selection of proportions.