Facts & Figures Book - KPI-JCI

ACTUAL GRADATIONThe ideal gradation is seldom, if ever, met in naturallyoccurringsand or gravel. In practice, the quality of thegradation of the aggregate, the workability of the concrete,cement and asphalt requirements must be balanced toachieve strength and other qualities desired, at minimumtotal cost.Sizing of material larger than No. 8 sieve is best and mosteconomically done by the use of mechanical screens ofvarious types, either dry or wet. In actual practice, however,the division between coarse aggregates, whichrequire different equipment for sizing, is set at No. 4 sieve(Fig. 3).Percent Weight RetainedSieve Allowable Sample TestedNo.Cumulative Individual CumulativeMin. Max.3 ⁄8” 0 0 0 04 0 10 4 48 10 35 11 1516 30 55 27 4230 55 75 28 7050 80 90 18 88100 92 98 8 96Pan 100 100 4 100FIGURE NO. 3Tables have been published to facilitate these calculations,and they are based on the maximum size of the coarseaggregate which can be used for the specific type of constructionplanned.13