To determine the total tonnage of plant mix required for a given paving area, the compacted

volume in cubic feet is multiplied by the unit weight of the mix in pounds per cubic foot. Unit

weight may be determined with the Marshall Method, as described previously. When the exact

unit weight of a plant mix has not been determined, an estimated weight of 160 pounds per cubic

foot may be used. (Unit weight is usually between 140 pounds and 160 pounds compacted cubic

foot.) The formulas used for this method of plant mix are:

Binder: tons of plant mix x OCA = Tons of AC

Aggregate: Tons of plant mix-tons of AC = Tons of

Aggregate (AGG)

where:

L = length of paveed area in feet

W = width of paved area in feet

LF = loss factor, if it is known

FCT = final compacted thickness in inches or the depth of the pavement in inches after the

completion of all compaction operations

UW = the exact unit weight of compacted plant mix in pounds per cubic foot

24,000 = 2000 x 12 or pounds per ton and inches per foot conversion factor

Example: A 2-inch thickness of plant mix is desired on a 110 foot by 650 foot parking lot. Find

the tons of plant mix required for this project if the unit weight of plant mix is 147

pounds per cubic foot.

SOLUTION:

L = 650 feet

W = 10 feet

FCT = 2 inches

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